02. Request&Response

石头大约 30 分钟

前言

学习目标

理解Request、Response和HTTP报文之间的关系
掌握通过Request能够获得的信息
请求URL、URI、请求协议
请求头、客户机和主机
请求参数
掌握通过Response能够完成的设置
响应中文乱码问题
响应（Json）字符串、图片（文件）
了解特殊的响应头
逐步通过反射能够解决一些通用问题

前置知识准备

HTTP 请求报文和响应报文
请求报文和响应报文分别包含哪些部分
反射reflect
获得Class对象
获得成员变量并给成员变量赋值
获得方法并且能够调用指定方法
MyBatis的基本使用
通过form表单分别构造get请求和post请求，能构造文件上传的请求
解析字符串获得其中的信息

请求报文

请求报文的组成部分

请求行
- 请求方法
- 请求的URL http://localhost:8080/hello
- 请求协议
请求头
- 格式是key：value
- 比较特殊的请求头：
  - Content-Type 由浏览器提供给服务器的正文类型
  - Accept 浏览器期望从服务器获得正文的类型（服务器提供给浏览器的正文类型）
  - Host 主机ip
（空行）
请求正文
- 普通的Get请求和form表单提供的Get/Post请求如果携带了参数它的格式是 key1=value1&key2=value2&key3=value3等
- 携带Json数据的post请求 {}或[]
- 图片/文件

POST http://101.43.69.31:8083/admin/auth/login HTTP/1.1
Host: 101.43.69.31:8083
Connection: keep-alive
Content-Length: 45
Accept: application/json, text/plain, */*
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.0.0 Safari/537.36 Edg/109.0.1518.78
Content-Type: application/json;charset=UTF-8
Origin: http://101.43.69.31:8080
Referer: http://101.43.69.31:8080/
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8,en-GB;q=0.7,en-US;q=0.6

{"username":"admin123","password":"admin123"}

分析一个请求体

对应的form表单如下

<form action="/hello" enctype="multipart/form-data" method="post">
    <input type="text" name="username"><br>
    <input type="text" name="password"><br>
    <input type="file" name="avatar"><br>

    <input type="submit" value="Submit">
</form>

响应报文

响应报文的组成

响应行
- 协议
- 状态码
响应头
- 格式是key=value
- Content-Type 服务器提供给浏览器的正文类型，后面通常会跟charset，比如application/json;charset=utf-8
（空行）
响应正文
- 如果是json，Content-Type中通常是application/json

HTTP/1.1 200
Vary: accept-encoding,origin,access-control-request-headers,access-control-request-method,accept-encoding
Set-Cookie: rememberMe=deleteMe; Path=/; Max-Age=0; Expires=Sun, 12-Feb-2023 06:51:56 GMT
Set-Cookie: JSESSIONID=24287278-5ebb-407d-a3f7-56b74782c4c7; Path=/; HttpOnly
Access-Control-Allow-Origin: *
Content-Type: application/json;charset=UTF-8
Date: Mon, 13 Feb 2023 06:51:56 GMT
Content-Length: 200

{"errno":0,"data":{"adminInfo":{"nickName":"admin123","avatar":"https://wpimg.wallstcn.com/f778738c-e4f8-4870-b634-56703b4acafe.gif"},"token":"24287278-5ebb-407d-a3f7-56b74782c4c7"},"errmsg":"成功"}

反射

获得Class对象

获得Class对象的方式

定义了一个类，这个类，处于com.cskaoyan.service包下，类名为UserServiceImpl，我们想要获得这个Class对象，如何获得呢？

UserServiceImpl.class
UserServiceImpl userService = new UserServiceImpl();
useService.getClass();
Class.forName("com.cskaoyan.service.UserServiceImpl")

Class<UserServiceImpl> clazz1 = UserServiceImpl.class;

UserServiceImpl userService = new UserServiceImpl();
Class<? extends UserServiceImpl> clazz2 = userService.getClass();

Class<?> clazz3 = Class.forName("com.cskaoyan.service.UserServiceImpl");

如果我们想要使用一些通用性的代码，我们用哪种方式？

Class.forName

public static void main(String[] args) throws IOException, ClassNotFoundException, IllegalAccessException, InstantiationException {
    InputStream inputStream = DriverDemo.class.getClassLoader().getResourceAsStream("parameter.properties");
    Properties properties = new Properties();
    properties.load(inputStream);

    String driver = (String) properties.get("driver");

    Class<?> driverClass = Class.forName(driver);

    Object instance = driverClass.newInstance();
}

# parameter.properties
# driver=com.cskaoyan.service.UserServiceImpl
driver=com.mysql.cj.jdbc.Driver

我们使用的mysql版本是5.7，对应的驱动是com.mysql.jdbc.Driver

如果使用mysql版本8，对应的驱动com.mysql.cj.jdbc.Driver

获得成员变量并给成员变量赋值

// 通过class能够获得实例
// 可以直接使用newInstance方法
Object instance1 = clazz3.newInstance();
// 可以先获得构造器（构造方法），通过构造方法实例化
Constructor<?> constructor = clazz3.getDeclaredConstructor();
Object instance2 = constructor.newInstance();

// 利用反射方式获得Field，通过反射的方式复制
Field usernameField = clazz3.getDeclaredField("username"); // user3.setUsername("")
usernameField.setAccessible(true);
usernameField.set(instance2,"zhangsan");// instance2的username这个成员变量赋值zhangsan
                                        // instance2.username = "zhangsan";

// 我们并不建议直接通过反射的方式给成员变量赋值，我们建议使用set方法做赋值

获得方法并且能够调用方法

//UserServiceImpl userServiceImpl = (UserServiceImpl) instance1;
//userServiceImpl.setUsername("lisi");
// 通过反射的方式实现通用性的设置

Properties properties = new Properties();
properties.load(ReflectExecution.class.getClassLoader().getResourceAsStream("parameter.properties"));
String className = (String) properties.get("className");
String method = (String)properties.get("method");
String value = (String)properties.get("value");

Class<?> clazz = Class.forName(className);
Object instance = clazz.newInstance();//instance的username成员变量是否是lisi
Method declaredMethod = clazz.getDeclaredMethod(method, String.class);
declaredMethod.setAccessable("true");
Object invoke = declaredMethod.invoke(instance, value);
// method.invoke

Object invoke = method.invoke(instance,args)

变量名	类型	含义
method	Method → clazz.getDeclaredMethod	通过反射获得的Method
instance	Object 1. new XXX ; 2.反射,比如clazz.newInstance	就是实例（对象）
args	Object[]	参数，把所有的参数封装为数组
invoke	Object	instance对象执行method的返回值

/**
 * 通过反射的方式执行UserServiceImpl中的sayHello
 */
public static void main(String[] args) throws Exception{
    Properties properties = new Properties();
    properties.load(ReflectExecution.class.getClassLoader().getResourceAsStream("parameter.properties"));
    String className = (String) properties.get("className");
    String method = (String)properties.get("method");
    String value = (String)properties.get("value");
    //String parameter1 = (String)properties.get("parameter1");
    //String parameter2 = (String)properties.get("parameter2");
    Object parameter1 = properties.get("parameter1");
    Object parameter2 = properties.get("parameter2");

    Class<?> clazz = Class.forName(className);
    Object instance = clazz.newInstance();

    Method setUsername = clazz.getDeclaredMethod("setUsername", String.class);
    setUsername.invoke(instance, value);

    //Method declaredMethod = clazz.getDeclaredMethod(method, String.class,String.class);
    Method declaredMethod = clazz.getDeclaredMethod(method, parameter1.getClass(),parameter2.getClass());
    //执行sayHello方法
    Object result = declaredMethod.invoke(instance, new Object[]{parameter1, parameter2});
}

MyBatis

SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis.xml"));
// 在整个应用程序中维护这个对象，想要在多个Servlet中共享这个对象
// ServletContext
// 提供一个Servlet，loadOnStartup为正数，且数值比较小，这个Servlet在应用程序启动过程中就会率先开始初始化，我们就可以利用生命周期的init方法去初始化SqlSessionFactory实例，并且将其放入到ServletContext中

概述

Request 请求

Response 响应

先看我们之前开发的Servlet，在Servlet中的service以及HttpServlet的doGet、doPost方法中的形参

public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

}

在Tomcat的时候就会产生Request，同时也会产生Response

可以这样子理解，当我们通过浏览器（或客户端）发送请求，在服务器应用中整个过程中的信息流通都是通过Request、Response流通的

Request：获得提供的信息，主要使用的是其getXXX方法

Response：设置信息提供给客户端（浏览器），主要使用的是其setXXX方法

每次发起请求，其实产生一组新的Request和Response对象

记住一个点：使用Request主要为了输入，使用Response主要为了输出

。

为了提供统一的规范，提供统一的规范接口ServletRequest和ServletResponse，为什么提供的是接口，接口能够提供统一的规范

Request

HttpServletRequest 获得HTTP请求报文中携带的信息

POST http://101.43.69.31:8083/admin/auth/login HTTP/1.1
Host: 101.43.69.31:8083
Connection: keep-alive
Content-Length: 45
Accept: application/json, text/plain, */*
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.0.0 Safari/537.36 Edg/109.0.1518.78
Content-Type: application/json;charset=UTF-8
Origin: http://101.43.69.31:8080
Referer: http://101.43.69.31:8080/
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8,en-GB;q=0.7,en-US;q=0.6

{"username":"admin123","password":"admin123"}

请求报文的组成

请求行
请求头
（空行）
请求体

请求行

POST http://101.43.69.31:8083/admin/auth/login HTTP/1.1

GET http://localhost:8080/demo3/hello?username=zhangsan HTTP/1.1

信息	内容	方法	返回值	说明
请求方法	POST、GET	getMethod()	String	获得请求方法
URL	http://101.43.69.31:8083/admin/auth/login	getRequestURL()	StringBuffer	获得请求URL
URI	/admin/auth/login、/demo3/hello	getRequestURI()	String	获得请求URI
context-path	/demo3	getContextPath()	String	获得上下文
服务器ip	101.43.69.31、localhost	getLocalAddr()	String	获得ip
端口号	8083、8080	getLocalPort()	int	获得端口号
QueryString	username=zhangsan	getQueryString()	String	获得Get请求的查询字符串
协议	HTTP/1.1	getProtocol()	String	获得通讯协议

代码

@WebServlet("/line")
public class LineServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse resp) throws ServletException, IOException {
        // http://localhost:8080/demo3/line?username=zhangsan
        // http://192.168.0.180:8080/demo3/line?username=zhangsan
        // 192.168.0.180可以修改为自己的ip
        
        // 请求方法
        String method = request.getMethod();
        // 请求URL和URI
        String url = request.getRequestURL().toString();
        String uri = request.getRequestURI();

        // 服务器本地的IP和端口号
        String localAddr = request.getLocalAddr();
        int localPort = request.getLocalPort();

        // 应用的上下文路径
        String contextPath = request.getContextPath();

        // 请求协议
        String protocol = request.getProtocol();


    }
}

请求头

Host: 101.43.69.31:8083
Connection: keep-alive
Content-Length: 45
Accept: application/json, text/plain, */*
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.0.0 Safari/537.36 Edg/109.0.1518.78
Content-Type: application/json;charset=UTF-8
Origin: http://101.43.69.31:8080
Referer: http://101.43.69.31:8080/
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8,en-GB;q=0.7,en-US;q=0.6

请求头中的信息，都是key：value的形式

可以知道有哪一些请求头 Key → 获得所有的请求头
也可以知道这些请求头当中的值是什么 Value → 获得特定Key对应的Value

方法	返回值	说明
getHeaderNames()	Enumeration<String>	获得所有的请求头，可以通过遍历的方式来使用，使用方式类似于Iterator
getHeader(String)	String	传入的是请求头的Key，返回的是请求头的value

构造一个请求，请求报文

GET http://192.168.0.180:8080/demo4/header HTTP/1.1
Host: 192.168.0.180:8080
Connection: keep-alive
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/110.0.0.0 Safari/537.36 Edg/110.0.1587.41
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8,en-GB;q=0.7,en-US;q=0.6

代码

@WebServlet("/header")
public class HeaderServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse resp) throws ServletException, IOException {
        Enumeration<String> headerNames = request.getHeaderNames();
        System.out.println("所有的请求头");
        while (headerNames.hasMoreElements()) {
            String headerName = headerNames.nextElement();
            System.out.println(headerName);
        }

        // 想要获得Host请求头的值
        String hostValue = request.getHeader("Host");
        System.out.println("hostValue = " + hostValue);
    }
}

控制台输出的结果

所有的请求头
host
connection
cache-control
upgrade-insecure-requests
user-agent
accept
accept-encoding
accept-language
hostValue = 192.168.0.180:8080

可以直接输入对应的key-value

Enumeration<String> headerNames = request.getHeaderNames();
System.out.println("所有的请求头");
while (headerNames.hasMoreElements()) {
    String headerName = headerNames.nextElement();
    String headerValue = request.getHeader(headerName);
    System.out.println(headerName + ":" + headerValue);
}

小练习：能够判断，是否包含某个请求头呢?如果包含，请把对应值打印出来

注意事项：请求头大小写不敏感

// 想要获得Host请求头的值
String hostValue = request.getHeader("Host");
String hostValue2 = request.getHeader("host");
String hostValue3 = request.getHeader("HOST");

请求体

请求报文是

POST http://localhost:8080/demo5/body HTTP/1.1
User-Agent: PostmanRuntime/7.29.2
Accept: */*
Host: localhost:8080
Accept-Encoding: gzip, deflate, br
Connection: keep-alive
Content-Type: application/x-www-form-urlencoded
Content-Length: 17

username=zhangsan

请求体的部分

username=zhangsan

字节流InputStream、字符流Reader

内容	方法	返回值	描述
字节流	getInputStream()	ServletInputStream	获得字节流
字符流	getReader()	BufferedReader	获得字符流

字节流

@WebServlet("/body1")
public class BodyServlet1 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse resp) throws ServletException, IOException {
        ServletInputStream inputStream = request.getInputStream();
        File file = new File("D:\\tmp", "1.txt");
        FileOutputStream outputStream = new FileOutputStream(file);
        
        int length = 0;
        byte[] bytes = new byte[1024];
        while ((length = inputStream.read(bytes)) != -1) {
            outputStream.write(bytes,0,length);
        }
        outputStream.close();
        inputStream.close();
    }
}

字符流

@WebServlet("/body2")
public class BodyServlet2 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse resp) throws ServletException, IOException {
        BufferedReader reader = request.getReader();
        File file = new File("D:\\tmp", "2.txt");
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(file));
        String str = null;
        while ((str = reader.readLine()) != null) {
            bufferedWriter.write(str);
        }
        bufferedWriter.flush();
        bufferedWriter.close();
        reader.close();
    }
}

特殊信息

客户机和服务器主机信息(了解)

请求是从客户机发到服务器的，在服务器中处理信息的获得，那么对于服务器，本地local是服务器，远程remote是客户机

我们在Servlet中可以获得本地的IP和Port，也可以获得远程IP和Port

信息	方法	返回值
本地（服务器）IP	getLocalAddr()	String
本地（服务器）端口号	getLocalPort()	int
远程（客户机）IP	getRemoteAddr()	String
远程（客户机）端口号	getRemotePort()	int

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    // 获得服务器端的信息
    String localAddr = req.getLocalAddr();
    int localPort = req.getLocalPort();

    // 获得客户机端的信息
    String remoteAddr = req.getRemoteAddr();
    int remotePort = req.getRemotePort();

    System.out.println("由" + remoteAddr + ":" + remotePort + "发送到" + localAddr + ":" + localPort);
}

★请求参数

请求参数的场景：

请求参数在请求行中
- getQueryString()
请求参数在请求体中
- getInputStream()/getReader()

指的是key=value&key=value

@WebServlet("/origin")
public class OriginServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse resp) throws ServletException, IOException {
        String parameterString = null;
        if ("GET".equals(request.getMethod())) {
            parameterString = request.getQueryString();
        }else {
            //ServletInputStream inputStream = request.getInputStream();
            //byte[] bytes = new byte[1024];
            //inputStream.read(bytes);
            //parameterString = new String(bytes);
            BufferedReader reader = request.getReader();
            parameterString = reader.readLine();
        }
        Map<String,String> parameterMap = executeMap(parameterString);
        String username = parameterMap.get("username");

        System.out.println(username);
    }

    private Map<String, String> executeMap(String parameterString) {
        HashMap<String, String> map = new HashMap<>();
        if (parameterString == null || "".equals(parameterString)) {
            return map;
        }
        //parameterArray[0] = "username=zhangsan"
        //parameterArray[1] = "password=lisi"
        String[] parameterArray = parameterString.split("\\&");
        for (String parameter : parameterArray) {
            int index = parameter.indexOf("=");
            String key = parameter.substring(0,index);
            String value = parameter.substring(index + 1, parameter.length());
            map.put(key, value);

        }
        return map;
    }
}

直接封装

但是实际开发中并不需要我们自己这么做，因为Request已经帮我们封装了可以直接使用的方法了

request.getParameterXXX这样的一些方法

方法	返回值	说明
getParameterNames()	Enumeration<String>	获得所有的key
getParameterMap()	Map<String,String[]>	获得所有的请求参数
getParameter(String)	String	获得第一个值
getParameterValues(String)	String[]	获得所有值

request对于请求参数的封装实际上，封装为一个Map<String,String[]>

/**
 * GET http://localhost:8080/demo7/parameter?key1=a1&key1=a2&key1=a3&key2=b1&key2=b2&key2=b3&key3=c1&key3=c2&key3=c3
 * key1: a1,a2,a3
 * key2: b1,b2,b3
 * key3: c1,c2,c3
 * @author stone
 * @date 2023/02/14 16:49
 */
@WebServlet("/parameter")
public class ParameterServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse resp) throws ServletException, IOException {
        Map<String, String[]> parameterMap = request.getParameterMap();
        Enumeration<String> parameterNames = request.getParameterNames();
        while (parameterNames.hasMoreElements()) {
            String parameterName = parameterNames.nextElement();
            System.out.println("parameterName = " + parameterName);
        }

        String key1 = request.getParameter("key1");
        System.out.println("key1 = " + key1);

        String[] key1s = request.getParameterValues("key1");
        System.out.println("key1s = " + Arrays.asList(key1s));
    }
}

引用类型

GET http://localhost:8080/demo7/register?username=root&password=123456&age=20&birthday=2000-10-15 HTTP/1.1

将请求参数封装为一个引用类型的对象，比如User

个性化（并不是一个褒义词）

User user = new User();
user.setUsername(request.getParameter("username"));
user.setPassword(request.getParameter("password"));

反射

BeanUtils.transfer(instance,parameterMap);//通过自己写的工具类，进行转换

public class WdBeanUtils {
 @SneakyThrows
 public static <T> T transfer(Class<T> clazz, Map<String, String[]> parameterMap) {
     // 先创建clazz对应的实例
     T instance = clazz.newInstance();

     // 给其成员变量赋值 →
     // 反射直接给成员变量赋值 field.set(instance,value)
     // 反射通过set方法间接给成员变量赋值 setMethod.invoke(instance,value)

     Iterator<String> iterator = parameterMap.keySet().iterator();
     // 反射直接给field赋值
     // giveFieldValue(clazz, parameterMap, instance, iterator);

     // 反射直接调用set方法，给set方法传入形参，通过形参给field赋值
     giveMethodValue(clazz, parameterMap, instance, iterator);

     // 赋值完成之后给其返回去
     return instance;
 }

 private static <T> void giveMethodValue(Class<T> clazz, Map<String, String[]> parameterMap, T instance, Iterator<String> iterator) throws NoSuchFieldException, NoSuchMethodException, IllegalAccessException, InvocationTargetException {
     while (iterator.hasNext()) {
         String fieldName = iterator.next();
         // 拼接set方法名
         // username → setUsername
         // password → setPassword
         // fieldName 首字母大写
         char[] chars = fieldName.toCharArray();
         chars[0] -= 32;
         String upperFirst = new String(chars);
         String setMethodName = "set" + upperFirst;

         // 获得形参的类型 → 成员变量的类型
         Field field = clazz.getDeclaredField(fieldName);
         Class<?> type = field.getType();
         Method method = clazz.getDeclaredMethod(setMethodName, type);//set方法

         String[] value = parameterMap.get(fieldName);

         if (field.getType().isArray()) {
             method.invoke(instance, (Object) value);
         } else {
             //method.invoke(instance, value);
             method.invoke(instance, value[0]);
         }

     }
 }

 private static <T> void giveFieldValue(Class<T> clazz, Map<String, String[]> parameterMap, T instance, Iterator<String> iterator) throws NoSuchFieldException, IllegalAccessException {
     while (iterator.hasNext()) {
         // 请求参数名 → 成员变量名
         String fieldName = iterator.next();
         Field field = clazz.getDeclaredField(fieldName);
         field.setAccessible(true);
         // 判断field对应的成员变量的类型是否是数组，
         // 如果是数组，给其的值是value
         // 如果不是数组，给其的值是value[0]
         String[] value = parameterMap.get(fieldName);
         if (field.getType().isArray()) {
             field.set(instance, value);
         } else {
             field.set(instance, value[0]);
         }
     }
 }
}

BeanUtils

引入依赖commons-beanutils

BeanUtils.copyProperties(instance, parameterMap);//直接使用其提供的copyProperties方法

Post请求请求参数乱码

乱码问题：编解码不一致

构造一个form表单，一个Get请求，一个是Post请求，分别去获得请求参数，查看通过Get和Post请求获得的请求参数

<h1>GET请求</h1>
<form action="/demo8/parameter" method="get">
    <input name="username"><input type="submit">
</form>
<h1>POST请求</h1>
<form action="/demo8/parameter" method="post">
    <input name="username"><input type="submit">
</form>

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse resp) throws ServletException, IOException {
    request.setCharacterEncoding("utf-8");
    String username = request.getParameter("username");
    System.out.println("username = " + username);
}

文件上传

在实际的开发过程中，有些场景需要做文件上传，比如上传头像，上传商品的描述图片等。

我们首先来看文件上传的请求的form表单如何构造
然后来看其对应的请求报文是什么样子的，然后我们在做进一步的分析

创建了一个form表单如下

<form action="/demo9/upload" enctype="multipart/form-data" method="post">
    用户：<input type="text" name="username"><br>
    头像：<input type="file" name="avatar"><br>
    <input type="submit" name="提交">
</form>

显示效果如下

然后构造请求数据

接下来发送请求，并且通过fiddler来抓取请求报文

POST http://localhost:8080/demo9/upload HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Content-Length: 1148487
Cache-Control: max-age=0
sec-ch-ua: "Chromium";v="110", "Not A(Brand";v="24", "Microsoft Edge";v="110"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "Windows"
Upgrade-Insecure-Requests: 1
Origin: http://localhost:8080
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary1pgACDbBGFGBPZYi
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/110.0.0.0 Safari/537.36 Edg/110.0.1587.63
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: navigate
Sec-Fetch-User: ?1
Sec-Fetch-Dest: document
Referer: http://localhost:8080/demo15/upload.html
Accept-Encoding: gzip, deflate, br
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8,en-GB;q=0.7,en-US;q=0.6
Cookie: Idea-dcbc35b9=2a0b80c2-0c01-4b8f-846d-d0915e770aa6

------WebKitFormBoundary1pgACDbBGFGBPZYi
Content-Disposition: form-data; name="username"

wangdao
------WebKitFormBoundary1pgACDbBGFGBPZYi
Content-Disposition: form-data; name="avatar"; filename="logo.png"
Content-Type: image/png

 PNG

   
IHDR             v    	pHYs  .#  .#x ?v  _iCCPPhotoshop ICC profile  xڭ ?( q   ?]  n0 ʟ 3  (ud  L   z _  7)  A   20$ 后面省略了很多很多内容

我们来分析一下上面的请求报文，首先能够进入眼帘的是，响应报文中出现了一堆未知的字符

这些内容其实包含了图片的字节数据

另外在请求信息之间出现了这样的一块内容,出现了两次

------WebKitFormBoundary1pgACDbBGFGBPZYi

这块内容其实就是分隔符，用来分割普通的请求数据和文件的请求数据的，在上面的请求头Content-Type的值中也可以看到。如果我们拿到请求体中的内容，通过分隔符，也就可以拿到图片的字节数据，拿到字节数据的话就可以通过OutputStream做写出了

但是呢，这个过程如果我们自己来完成的话，非常的复杂。在Servlet3.0之前，我们可以借助第三方工具来封装，比如commons-fileupload（FileUpload – Using FileUpload (apache.org)open in new window），但是这个过程仍然是非常繁琐。

Servlet3.0提供了对文件上传的支持，通过@MultipartConfig标注和HttpServletRequest提供的方法可以完成文件部分的获取，我们当前可以使用Request中的getPart方法直接拿到其图片部分

Part getPart(String var1) throws IOException, ServletException;

该方法的参数需要传入一个字符串值，该值是请求参数名，如果拿的是上面请求中图片文件的信息，则需要传入 avatar

<!--intput标签中的name属性值其实就是请求参数名，分隔符中name对应的值也是这个-->
头像：<input type="file" name="avatar"><br>

获得Part对象，通过Part中提供的方法可以获得其他具体的信息

方法	返回值	说明
getInputStream()	InputStream	获得字节输入流，可以读取字节数据将其保存下来
getContentType()	String	获得正文类型，比如png图片，其值为image/png
getSize()	long	获得文件字节大小
getName()	String	获得请求参数名（这里就是avatar）
getSubmittedFileName()	String	获得上传的原始文件名（这里是logo.png）

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    Part avatar = req.getPart("avatar");
    InputStream inputStream = avatar.getInputStream();
    String contentType = avatar.getContentType();
    long size = avatar.getSize();
    String name = avatar.getName();
    String submittedFileName = avatar.getSubmittedFileName();
}

如果要将图片以原始文件名保存在web资源根目录，我们可以写这样的代码

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    Part avatar = req.getPart("avatar");
    InputStream inputStream = avatar.getInputStream();
    String submittedFileName = avatar.getSubmittedFileName();

    byte[] bytes = new byte[1024];
    int length = 0;
    FileOutputStream outputStream = new FileOutputStream(new File(getServletContext().getRealPath(submittedFileName)));
    while ((length = inputStream.read(bytes)) != -1) {
        outputStream.write(bytes, 0, length);
    }
    inputStream.close();
}

Request做请求转发（了解）

实际开发过程中，基本不会再涉及到，当前基本上不再使用JSP技术，JSP技术使用过程中会做请求转发。

JSP，而JSP是一种特殊的Servlet

但是jsp目前已经没有什么使用场景了。目前架构主要是前后端分离。所以关于转发了解即可。

如果是jsp的话，jsp其实也是一个servlet

可以通过IDEA中的Tomcat的CATALINA_BASE看一下其生成的jsp 相关的java文件

请求转发，其实就是在一个Servlet处理业务，处理完业务，继续由另外一个Servlet处理业务。

其中一个关注点，转发的两个请求之间的数据共享

Request域，转发的请求之间数据共享

request.setAttribute
request.getAttribute

Response

响应报文的封装，设置响应报文

HTTP/1.1 200
Vary: accept-encoding,origin,access-control-request-headers,access-control-request-method,accept-encoding
Set-Cookie: rememberMe=deleteMe; Path=/; Max-Age=0; Expires=Sun, 12-Feb-2023 06:51:56 GMT
Set-Cookie: JSESSIONID=24287278-5ebb-407d-a3f7-56b74782c4c7; Path=/; HttpOnly
Access-Control-Allow-Origin: *
Content-Type: application/json;charset=UTF-8
Date: Mon, 13 Feb 2023 06:51:56 GMT
Content-Length: 200

{"errno":0,"data":{"adminInfo":{"nickName":"admin123","avatar":"https://wpimg.wallstcn.com/f778738c-e4f8-4870-b634-56703b4acafe.gif"},"token":"24287278-5ebb-407d-a3f7-56b74782c4c7"},"errmsg":"成功"}

响应报文的组成

响应行
响应头
(空行)
响应体（正文）
- 字符信息
- 字节信息

响应行

协议就不设置了，设置一下响应状态码

方法名	参数	说明
setStatus(int)	参数就是状态码	设置响应状态码

@WebServlet("/line")
public class LineServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse response) throws ServletException, IOException {
        response.setStatus(302);
    }
}

发送请求后接收到的响应报文

HTTP/1.1 302
Content-Length: 0
Date: Wed, 15 Feb 2023 03:20:18 GMT
Keep-Alive: timeout=20
Connection: keep-alive

响应头

响应头也是key：value的格式，提供了通用的方法，可以设置响应头的key和value；也提供了一些特定的方法，特定的方法做的事情，就是设置特定响应头的值

方法	参数	说明
setHeader(String,String)	参数1提供key，参数2提供value	通用的方法

@WebServlet("/header")
public class HeaderServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse response) throws ServletException, IOException {
        // 第一个参数是key，第二个参数是value
        response.setHeader("custom-header","abcdef");
    }
}

HTTP/1.1 200
custom-header: abcdef
Content-Length: 0
Date: Wed, 15 Feb 2023 03:28:04 GMT
Keep-Alive: timeout=20
Connection: keep-alive

响应体

响应体（正文）

可以使用字符流，也可以使用字节流。

方法	返回值	描述
getWriter()	PrintWriter	字符流
getOutputStream()	ServletOutputStream	字节流

字符流

@WebServlet("/body1")
public class BodyServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //resp.getWriter().println("hello world");
        //resp.getWriter().append("hello world");
        resp.getWriter().write("hello world");
    }
}

@WebServlet("/body2")
public class BodyServlet2 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletOutputStream outputStream = resp.getOutputStream();
        InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream("dlrb.jpg");
        byte[] bytes = new byte[1024];
        int length = 0;
        while ((length = inputStream.read(bytes)) != -1) {
            outputStream.write(bytes,0,length);
        }
        inputStream.close();
    }
}

场景：

字符流：响应文本数据，最主要的场景就是前后端分离之后，通过字符流响应Json数据
字节流：响应图片、文件，也通常在文件下载的场景下使用

特殊响应头

特殊的几个响应头

refresh → 定时刷新、跳转
content-type → 限定响应的正文（也可以解决中文乱码问题）
content-disposition → 文件下载
location → 重定向

refresh

private void refreshAndForward(HttpServletResponse resp) {
    resp.setHeader("refresh","3;url=/demo12/hello");
}

private void refreshPerSecond(HttpServletResponse resp) throws IOException {
    resp.setHeader("refresh","1");
    Date date = new Date();
    String dateStr = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(date);
    resp.getWriter().write(dateStr);
}

Content-Type

通常不需要设置

比如我们响应Json数据给前端，我们可以设置Content-Type：application/json

我们要在这里做字符集的设置，如果没有做有可能出现中文乱码

比如我们响应Json，想要设置字符集为utf-8

Content-Type:application/json;charset=utf-8

@WebServlet("/contenttype")
public class ContentTypeServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 这里不是json而是普通字符，就设置了text/html了
        resp.setHeader("content-type","text/html;charset=utf-8");
        resp.getWriter().write("你好");
    }
}

也可以直接使用Response来调用其setContentType方法

content-disposition

下载的场景会使用

content-disposition: attachment;filename=1.jpg

以1.jpg来下载正文

@WebServlet("/disposition")
public class ContentDispositionServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setHeader("content-disposition","attachment;filename=1.jpg");
        ServletOutputStream outputStream = resp.getOutputStream();
        InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream("dlrb.jpg");
        byte[] bytes = new byte[1024];
        int length = 0;
        while ((length = inputStream.read(bytes)) != -1) {
            outputStream.write(bytes,0,length);
        }
        inputStream.close();
        outputStream.close();
    }
}

location

重定向

@WebServlet("/location")
public class LocationServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("访问到LocationServlet");
        resp.setStatus(302);
        resp.setHeader("location","http://localhost:8080/demo12/hello");
    }
}

注意事项

请求体和响应体分别要使用到输入流和输出流

关闭流，如果是通过request和response获得流，不手动关闭也可以；如果是自己创建的流，要及时关闭
同一个请求处理过程中，不能既获得字节流又获得字符流

案例

请求分发案例

场景：有多个请求
Http://localhost:8080/user/login → 登录
http://localhost:8080/user/create → 注册
http://localhost:8080/user/info → 查看用户信息

按照我们之前的写法，我们需要写3个Servlet，如果不想写3个Servlet，只写一个UserServlet可以不？

Servlet的url-pattern的合法写法 /xxx/*,我们在这个UserServlet上可否写一个/user/*

@WebServlet("/user/*")
public class UserServlet extends HttpServlet{
    
}

获得请求的URI，根据uri 的user后面的值的不同做不同的处理

@WebServlet("/user/*")
public class UserServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String requestURI = req.getRequestURI();
        // 截取URI字符串，举例 /demo13/user/login
        int index = requestURI.lastIndexOf("/");
        String operation =
            requestURI.substring(index + 1, requestURI.length());

        resp.setHeader("content-type","text/html;charset=utf-8");
        // 请求URI的最后一级
        if ("login".equals(operation)) {
            method1(req,resp);
        } else if ("create".equals(operation)) {
            method2(req,resp);
        } else if ("info".equals(operation)) {
            method3(req,resp);
        }
        //resp.getWriter().write(requestURI);
    }

    private void method1(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        resp.getWriter().write("访问登录");
    }
    private void method2(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        resp.getWriter().write("访问注册");

    }
    private void method3(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        resp.getWriter().write("访问查看信息");

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

登录案例

请求：先访问登录请求，登录如果成功，那么接着先提示登录成功，然后过两秒访问到info请求

这个请求由登录页面提供，我们可以通过html提供一个登录表单，该表单会发出请求

http://localhost:8080/user/login → Servlet → 检查用户名和密码是否正确（使用一下MyBatis） →

如果正确，那么就提示登录成功
如果错误，那么刷新登录页面

任务拆解：
包含登录表单的 login.html文件，放在webapp目录下
开发UserServlet
/user/login对应的处理方法，使用MyBatis做查询
/user/info对应的处理方法
整合MyBatis，在应用程序中维护SqlSessionFactory实例

/**
 * Servlet如果它的loadOnStartup为正数，则应用程序启动的时候初始化；
 * 如果为负数，则访问其URL-Pattern时才初始化
 * 想让其应用程序启动的时候就初始化 → 提供一个SqlSessionFactory的实例，然后共享该实例
 * @author stone
 * @date 2023/02/16 16:16
 */
@WebServlet(value = "/mybatis/init",loadOnStartup = 1)
public class MyBatisInitializationServlet extends HttpServlet {
    @SneakyThrows
    @Override
    public void init() throws ServletException {
        ServletContext servletContext = getServletContext();
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis.xml"));
        servletContext.setAttribute("sqlSessionFactory",sqlSessionFactory);
    }
}

@WebServlet("/user/*")
public class UserServlet extends HttpServlet {
    SqlSessionFactory sqlSessionFactory;
    @Override
    public void init() throws ServletException {
        sqlSessionFactory = (SqlSessionFactory) getServletContext().getAttribute("sqlSessionFactory");
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String operation = URIUtil.fetchOperation(req);
        switch (operation) {
            case "login":
                login(req, resp);
                break;
            case "info":
                info(req, resp);
                break;
            default:
                resp.setHeader("content-type","text/html;charset=utf-8");
                resp.getWriter().write("请求有误，请联系管理员");
        }

    }

    private void login(HttpServletRequest req, HttpServletResponse resp) throws UnsupportedEncodingException {
        // 判断用户名和密码是否符合要求
        //Object sqlSessionFactory = getServletContext().getAttribute("sqlSessionFactory");
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        req.setCharacterEncoding("utf-8");
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        CskaoyanUser cskaoyanUser = userMapper.selectByUsernameAndPassword(username, password);
        if (cskaoyanUser == null) {
            resp.setStatus(302);
            resp.setHeader("location","/demo14/login.html");
        }else {
            //先把user信息暂存一下
            getServletContext().setAttribute("user",cskaoyanUser);
            resp.setHeader("refresh","2;/demo14/user/info");
        }
    }
    private void info(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        CskaoyanUser user = (CskaoyanUser) getServletContext().getAttribute("user");
        System.out.println("user = " + user);
        resp.setHeader("content-type","text/html;charset= utf-8");
        resp.getWriter().write("欢迎你，" + user.getUsername());
    }


    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

（项目）会员管理

查询会员信息

GET http://101.43.69.31:8083/admin/user/list?page=1&limit=20&sort=add_time&order=desc HTTP/1.1
Host: 101.43.69.31:8083
Connection: keep-alive
Accept: application/json, text/plain, */*
X-CskaoyanMarket-Admin-Token: 85b7dffc-f6c6-4cf6-bc20-3c280f28f1bf
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36 Edg/116.0.1938.62
Origin: http://101.43.69.31:8080
Referer: http://101.43.69.31:8080/
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8,en-GB;q=0.7,en-US;q=0.6

请求URL是什么？
http://101.43.69.31:8083/admin/user/list
uri的部分 /admin/user/list
a. 配置tomcat的话，要考虑虚拟映射的path → /
b. 开发的Servlet的url-pattern，@WebServlet的value属性值 → /admin/user/*
c. 最后一级是list，如果集成BaseServlet的话，需要UserServlet中有一个名称为list的方法

@WebServlet("/admin/user/*")
public class UserServlet extends BaseServlet {

    public void list(HttpServletRequest request, HttpServletResponse response) {
        
    }
}

请求参数
a. request.getParameter相关的方法
(1). 在queryString里面出现了key=value形式的请求参数
(2). 请求体里出现key=value
b. request.getReader().readLine() 返回字符串信息
(1).请求体里出现字符串 → 使用使用这个方法获得的是Json
c. request.getPart() 获得Part对象
(1).multipart/form-data请求，通常会携带文件(字节数据) → Part中的getInputStream做处理
当前这个场景，我们的请求参数属于上面的哪种请求？ a1

@WebServlet("/admin/user/*")
public class UserServlet extends BaseServlet {

    //queryString的值 page=1&limit=20&sort=add_time&order=desc
    @SneakyThrows
    public void list(HttpServletRequest request, HttpServletResponse response) {
        //Integer page = Integer.valueOf(request.getParameter("page"));
        //Integer limit = Integer.valueOf(request.getParameter("limit"));
        //String sort = request.getParameter("sort");
        //String order = request.getParameter("order");
        BaseParam baseParam = new BaseParam();
        BeanUtils.copyProperties(baseParam,request.getParameterMap());
    }
}

在这里已经接收到请求参数，我们需要完成的业务？
增删改查中的哪一个或哪一些？
这里应该做查询 → 根据add_time做降序查询user表中的page和limit对应的user信息
-- limit 第一个值 (page -1) * limit -- limit 第二个值 limit SELECT * FROM market_user order by add_time desc limit 0,20

整合MyBatis完成上面的业务

@WebServlet("/admin/user/*")
public class UserServlet extends BaseServlet {

    SqlSessionFactory sqlSessionFactory = null;

    @Override
    public void init() throws ServletException {
        sqlSessionFactory = (SqlSessionFactory) getServletContext().getAttribute("sqlSessionFactory");
    }

    //queryString的值 page=1&limit=20&sort=add_time&order=desc
    @SneakyThrows
    public void list(HttpServletRequest request, HttpServletResponse response) {
        //Integer page = Integer.valueOf(request.getParameter("page"));
        //Integer limit = Integer.valueOf(request.getParameter("limit"));
        //String sort = request.getParameter("sort");
        //String order = request.getParameter("order");
        BaseParam baseParam = new BaseParam();
        BeanUtils.copyProperties(baseParam,request.getParameterMap());

        UserMapper mapper = sqlSessionFactory.openSession(true).getMapper(UserMapper.class);
        baseParam.initOffset();
        List<MarketUser> userList = mapper.selectUserList(baseParam);
    }
}

返回值什么样子？

我们刚刚只复制了请求报文，并不知道响应报文的响应体需要我们提供什么样的数据

应该找到相应报文，找到其中的响应体

HTTP/1.1 200
Vary: accept-encoding,origin,access-control-request-headers,access-control-request-method,accept-encoding
Access-Control-Allow-Origin: *
Content-Type: application/json;charset=UTF-8
Date: Tue, 29 Aug 2023 06:58:59 GMT
Content-Length: 9805
      
{"errno":0,"data":{"total":79,"pages":4,"limit":20,"page":1,"list":[{"id":80,"username":"user456","password":"$2a$10$KairBY9XjiT0IqTj10Fz3uUumKqlbSX0oVVhTpfhkis1eJV9VSjm2","gender":0,"lastLoginTime":"2023-08-14 21:09:29","lastLoginIp":"171.113.245.233","userLevel":0,"nickname":"user456","mobile":"15310888954","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-14 21:09:29","updateTime":"2023-08-29 11:42:24","deleted":false},{"id":79,"username":"wangshuai","password":"$2a$10$wpa0FmHqaE6aNWrGDtmh.O3/NiNhR3pxig38/WWDeuiQJbZL8teyy","gender":0,"lastLoginTime":"2023-08-13 21:43:30","lastLoginIp":"171.43.248.189","userLevel":0,"nickname":"wangshuai","mobile":"18839219012","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-13 21:43:30","updateTime":"2023-08-13 21:43:30","deleted":false},{"id":78,"username":"dsfnjdnc","password":"$2a$10$z1DC5UXeljtOECGST5Ht5un2UXYdHUY.zUoFVEuoU0Foqmg9KiET6","gender":0,"lastLoginTime":"2023-08-12 09:59:36","lastLoginIp":"171.43.248.189","userLevel":0,"nickname":"dsfnjdnc","mobile":"17889948070","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-12 09:59:36","updateTime":"2023-08-12 09:59:36","deleted":false},{"id":77,"username":"lipanl","password":"$2a$10$2e3ZiDI6yU/d9jDGh3ow2ubtBxAyVTaNUr5NrA2rw2coo/thKhkJO","gender":0,"lastLoginTime":"2023-08-12 09:26:55","lastLoginIp":"171.43.248.189","userLevel":0,"nickname":"lipanl","mobile":"15605215755","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-12 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08:52:56","updateTime":"2023-08-12 08:52:56","deleted":false},{"id":74,"username":"11tong","password":"$2a$10$xiufPksECD4y7WudNGleae6MDNabNUSDiEH4xz63V94PANvVCvjsG","gender":0,"lastLoginTime":"2023-08-11 23:41:56","lastLoginIp":"37.128.243.180","userLevel":0,"nickname":"11tong","mobile":"18193408088","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-11 23:04:45","updateTime":"2023-08-11 23:41:56","deleted":false},{"id":73,"username":"6666666","password":"$2a$10$4DGAP3HtGGf9fiJAR5FsUe580LglFuc8AlkwbQRhiofVz.2cfu1hu","gender":0,"lastLoginTime":"2023-08-11 22:28:46","lastLoginIp":"171.113.246.131","userLevel":0,"nickname":"6666666","mobile":"19149355","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-11 22:28:46","updateTime":"2023-08-11 22:53:53","deleted":false},{"id":72,"username":"shibowen","password":"$2a$10$xDgPrbO8hR1XhQf4bXxrP.Ly/vwWjXGtDtnShDUWB2DsTodOV/HWe","gender":0,"lastLoginTime":"2023-08-11 22:20:15","lastLoginIp":"171.113.246.131","userLevel":0,"nickname":"shibowen","mobile":"15364314469","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-11 22:20:15","updateTime":"2023-08-11 22:21:27","deleted":false},{"id":71,"username":"cpj123","password":"$2a$10$1ilmyiwiIIE3mIW9HZPYfenJRaEWDUZzj7u0sYYL1fLcTW58tf5Vi","gender":0,"lastLoginTime":"2023-08-12 10:59:52","lastLoginIp":"171.43.248.189","userLevel":0,"nickname":"cpj123","mobile":"15213480588","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-11 16:54:45","updateTime":"2023-08-12 10:59:52","deleted":false},{"id":70,"username":"qianqian","password":"$2a$10$9lZkUEdw1GVcBwk03L47JOetj8SRZDOun74fQ25gSJCXbuDUpXT6q","gender":0,"lastLoginTime":"2023-08-11 15:55:18","lastLoginIp":"38.181.73.70","userLevel":0,"nickname":"qianqian","mobile":"17302213266","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-11 15:55:18","updateTime":"2023-08-11 17:09:03","deleted":false},{"id":69,"username":"13428689333","password":"$2a$10$Fl3B9m6dRAJ42.ZJw5Vbsucgd8a7WE7YEJbGq2NMrrDejqfeM6vVC","gender":0,"lastLoginTime":"2023-08-11 14:39:58","lastLoginIp":"171.113.246.131","userLevel":0,"nickname":"13428689333","mobile":"13428689333","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-11 14:39:58","updateTime":"2023-08-11 14:41:19","deleted":false},{"id":68,"username":"141d54","password":"$2a$10$39XcI1ZFVlZ./Q4/hk9U2.t/2XvwfWZWlqhuhxtAzPCpICO7DS9Ku","gender":0,"lastLoginTime":"2023-08-11 12:52:49","lastLoginIp":"171.113.246.131","userLevel":0,"nickname":"141d54","mobile":"18571475083","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-11 12:52:49","updateTime":"2023-08-11 12:52:49","deleted":false},{"id":67,"username":"haodene","password":"$2a$10$3wUuWJgmJrswpf7vMjyNKu2QaS7OcIWMoJIoZqeA.j2QxZX0hc3Gq","gender":0,"lastLoginTime":"2023-08-11 12:38:06","lastLoginIp":"210.3.159.237","userLevel":0,"nickname":"haodene","mobile":"17332885067","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-11 12:38:06","updateTime":"2023-08-11 12:38:54","deleted":false},{"id":66,"username":"xn1111","password":"$2a$10$6NYttr6pchyPDRN776peiuMqI.P.tk2Nexu/ExPF2zLrpdsw91.UW","gender":0,"lastLoginTime":"2023-08-12 13:01:41","lastLoginIp":"171.43.247.130","userLevel":0,"nickname":"xn1111","mobile":"15543400379","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-11 12:17:09","updateTime":"2023-08-12 13:01:41","deleted":false},{"id":65,"username":"999999","password":"$2a$10$IVMS2c3U94iwOiu9gRpM...zuO9AEmjvz3q7hqIqtcog..nKp4d06","gender":0,"lastLoginTime":"2023-08-11 12:01:34","lastLoginIp":"171.113.246.131","userLevel":0,"nickname":"999999","mobile":"17863013913","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-11 12:01:34","updateTime":"2023-08-11 17:54:15","deleted":false},{"id":64,"username":"uer123","password":"$2a$10$8iSnFilcnMLl0SxgCnnniuxsTCwSJB/toW9QTK3L7Z6/NMggZpzFS","gender":0,"lastLoginTime":"2023-08-11 11:44:41","lastLoginIp":"38.181.73.70","userLevel":0,"nickname":"uer123","mobile":"17353291393","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-11 11:44:41","updateTime":"2023-08-11 11:44:41","deleted":false},{"id":63,"username":"aaaaaa","password":"$2a$10$xz7HJbKtqb0r4eFTXZHZrufncjSL8TLypxrQf1RtY30O6J4NFDF.O","gender":0,"lastLoginTime":"2023-08-11 10:37:50","lastLoginIp":"210.3.159.237","userLevel":1,"nickname":"aaaaaa","mobile":"17332855555","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":2,"addTime":"2023-08-11 10:37:50","updateTime":"2023-08-11 11:38:32","deleted":false},{"id":62,"username":"czc123","password":"$2a$10$CDVT5W1oGx7VpmVbR/y3jeSuul3cK2fKHYgXO0RSoJEOIwLRl6NKy","gender":0,"lastLoginTime":"2023-08-12 09:04:19","lastLoginIp":"171.43.248.189","userLevel":0,"nickname":"czc123","mobile":"15374579055","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-10 21:36:07","updateTime":"2023-08-12 09:04:19","deleted":false},{"id":61,"username":"wangao4","password":"$2a$10$SNfWiy4zIB9EZx39y5aaHuWgI32gC7.6V67l1OlreBPpWQHim0exe","gender":0,"lastLoginTime":"2023-08-10 19:59:31","lastLoginIp":"171.113.241.66","userLevel":0,"nickname":"wangao4","mobile":"13593956279","avatar":"https://yanxuan.nosdn.127.net/80841d741d7fa3073e0ae27bf487339f.jpg?imageView&quality=90&thumbnail=64x64","weixinOpenid":"","sessionKey":"","status":0,"addTime":"2023-08-10 19:59:31","updateTime":"2023-08-10 19:59:31","deleted":false}]},"errmsg":"成功"}

在浏览器中看到的json

@Data
public class UserListVo{
  Object data; // 跟着{ 可以Object或Map
  String errmsg;// 跟着 "
  int errno; // 跟着数据
             // 如果跟着[ 就是数组或List等集合类型
}

@Data
public class ListVo {
    Integer limit;
    List list;
    Integer page;
    Integer total;
    Integer pages;
}

@Data
public class ListVo {
    Integer limit;
    List<MarketUser> list;
    Integer page;
    Integer total;
    Integer pages;
}

介绍一个工具 GsonFormat（或GsonFormatPlus）安装之后，在类中使用alt+s快捷键

@NoArgsConstructor
@Data
public class GsonFormatVo {
    private Integer errno;
    private DataDTO data;
    private String errmsg;

    @NoArgsConstructor
    @Data
    public static class DataDTO {
        private Integer total;
        private Integer pages;
        private Integer limit;
        private Integer page;
        private List<MarketUser> list;
    }

    // alt + s
    
}

响应对应的JSON数据

令Servlet中的方法返回值为Object，BaseServlet就会将这个Object转换为Json字符串，然后使用字符输出流写出

@SneakyThrows
public UserListVo list(HttpServletRequest request, HttpServletResponse response) {
  //Integer page = Integer.valueOf(request.getParameter("page"));
  //Integer limit = Integer.valueOf(request.getParameter("limit"));
  //String sort = request.getParameter("sort");
  //String order = request.getParameter("order");
  BaseParam baseParam = new BaseParam();
  BeanUtils.copyProperties(baseParam,request.getParameterMap());
      
  UserMapper mapper = sqlSessionFactory.openSession(true).getMapper(UserMapper.class);
  baseParam.initOffset();
  List<MarketUser> userList = mapper.selectUserList(baseParam);
      
  UserListVo userListVo = new UserListVo();
  userListVo.setErrno(0);
  userListVo.setErrmsg("成功");
  ListVo data = new ListVo();
      
  data.setList(userList);
  data.setPage(baseParam.getPage());
  data.setLimit(baseParam.getLimit());
      
  //data.setPages();
  //data.setTotal();
      
  userListVo.setData(data);
  return userListVo;
}

小结

找Servlet
处理请求参数
在Servlet中根据参数完成对应业务处理(增删改查)
返回对应的json数据

写熟练了都是洒洒水

练习题

marketopen in new window

http://101.43.69.31:8080

开发对应的请求 → 行政区域

MyBatis的多表查询
查询出来使用Stream来做封装也可以

02. Request&Response

# 前言

# 学习目标

# 前置知识准备

# 请求报文

# 响应报文

# 反射

# 获得Class对象

# 获得成员变量并给成员变量赋值

# 获得方法并且能够调用方法

# MyBatis

# 概述

# Request

# 请求行

# 请求头

# 请求体

# 特殊信息

# 客户机和服务器主机信息(了解)

# ★请求参数

# 直接封装

# 引用类型

# Post请求请求参数乱码

# 文件上传

# Request做请求转发（了解）

# Response

# 响应行

# 响应头

# 响应体

# 特殊响应头

# refresh

# Content-Type

# content-disposition

# location

# 注意事项

# 案例

# 请求分发案例

# 登录案例

# （项目）会员管理

# 小结

# 练习题

前言