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第73节：Java中的HTTPServletReauest和HT

第73节：Java中的HTTPServletReauest和HT

作者: 魔王哪吒 | 来源:发表于2019-01-21 11:33 被阅读18次
标题图

第73节：Java中的HTTPServletReauest和HTTPServletResponse

HTTP协议

客户端与服务器端通讯的一种规则。

request:
请求行
请求头
请求体

response:
响应行
响应头
响应体

Get:
请求的时候带上的数据，在url上拼接，数据长度有限制

POST:
以流的方式写数据，数据没有限制

Content-Type: 数据类型
Content-Length: 多少长度的数据

Servlet入门：

写一个类，实现接口Servlet
注册 web.xml
<servlet>
 servlet-name: 自定义
 servlet-class: 全路径
 <init-params> 不必要写 -servletconfig
</servlet>
<servlet-mapping>
 <servlet-name>: 上面的servlet-name
 <url-patter>: 以正斜杠开头
</servlet-mapping>

servlet的生命周期：

init: 默认情况下初次访问时就会执行，服务器启动时，只能执行一次
提前：
<servlet>
 servlet-name:
 servlet-class:
 <load-on-startup>2</load-on-startup>
</servlet>

service: 可以执行多次，只要进行请求
destory：销毁的使用，销毁在从服务器中移除托管或shutdown.bat

// servlet
public class Demo implements Servlet {
 @Override
 void service(){
 ...
 }
}

// 优化
继承接口已有的实现类
// 抽象类一定有抽象方法，不一定，有抽象方法的，一定是抽象类
class Demo2 extends HttpServlet {
 void doGet();
 void doPost();
}

// 源码
public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
 HttpServletRequest request;
 HttpServletResponse response;
 
 try{
  request = (HttpServletRequest) req;
  response = (HttpServletResponse) res;
 }catch(ClassCastException e){
  throw new ServletException("non-HTTP request or response");
 }
 service(request,response);
}

HttpServletRequest和HttpServletResponse

效果 
package com.dashucoding.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Demo extends HttpServlet{
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("来了一个请求。。。");
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>ServletRegister</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
  <servlet>
   <servlet-name>demo</servlet-name>
   <servlet-class>com.dashucoding.servlet.Demo</servlet-class>
  </servlet>
  <servlet-mapping>
   <servlet-name>demo</servlet-name>
   <url-pattern>/demo</url-pattern>
  </servlet-mapping>
</web-app>
效果 结果

创建Server

效果 
// 创建ServletRegister ->  选择Servlet
package com.dashucoding.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class ServletRegister
 */
@WebServlet("/ServletRegister")
public class ServletRegister extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public ServletRegister() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.getWriter().append("Served at: ").append(request.getContextPath());
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

package com.dashucoding.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class ServletRegister
 */
public class ServletRegister extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.getWriter().append("Served at: ").append(request.getContextPath());
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>TestRegister</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <description></description>
    <display-name>ServletRegister</display-name>
    <servlet-name>ServletRegister</servlet-name>
    <servlet-class>com.dashucoding.servlet.ServletRegister</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>ServletRegister</servlet-name>
    <url-pattern>/ServletRegister</url-pattern>
  </servlet-mapping>
</web-app>
效果

Servlet配置路径方式：

* : 就是个通配符，匹配任意文字。
/a*
*.aa

ServletContext

// web.xml
// 用于配置全局的参数
<context-param>
 <param-name>dashu</param-name>
 <param-value>dashucoding</param-value>
</context-param>

// <init-param></init-param>

// 获取对象
ServletContext context = getServletContext();
// 获取参数值
String name = context.getInitParameter("dashu");
System.out.println("name=" + name);

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // 获取对象
    ServletContext context = getServletContext();
    // 获取参数值
    String name = context.getInitParameter("dashu");
    System.out.println("name=" + name);
}

获取资源文件

效果 
package com.dashucoding.servlet;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class Demo03
 */
public class Demo03 extends HttpServlet {
    
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
        // 获取ServletContext对象
        ServletContext context = getServletContext();
        // 获取给定的文件在服务器上面的绝对路径
        String path = context.getRealPath("");
        System.out.println("path=" + path);
        
        /*// 创建属性对象
        Properties properties = new Properties();

        // 指定载入的数据源
        InputStream is = new FileInputStream(path);
        properties.load(is);

        // 获取属性的值
        String name = properties.getProperty("name");
        System.out.println("name=" + name);*/
    }

    
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}
效果 效果 效果 
package com.dashucoding.servlet;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class Demo03
 */
public class Demo03 extends HttpServlet {
    
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
        // 获取ServletContext对象
        ServletContext context = getServletContext();
        // 获取给定的文件在服务器上面的绝对路径
        String path = context.getRealPath("/file/config.properties");
        System.out.println("path=" + path);
        
        // 创建属性对象
        Properties properties = new Properties();

        // 指定载入的数据源
        InputStream is = new FileInputStream(path);
        properties.load(is);

        // 获取属性的值
        String name = properties.getProperty("name");
        System.out.println("name=" + name);
    }

    
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}
效果 效果 
package com.dashucoding.servlet;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class Demo03
 */
public class Demo03 extends HttpServlet {
    
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
//      test01();
        test02();
    }
    // alt + shift + z
    private void test02() {
        try {
            // 获取ServletContext对象
            ServletContext context = getServletContext();
            
            // 创建属性对象
            Properties properties = new Properties();

            // 指定载入的数据源
            InputStream is = context.getResourceAsStream("/file/config.properties");
            properties.load(is);

            // 获取属性的值
            String name = properties.getProperty("name");
            System.out.println("name02=" + name);
            is.close();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    // alt + shift + m
    private void test01() throws FileNotFoundException, IOException {
        // 获取ServletContext对象
        ServletContext context = getServletContext();
        // 获取给定的文件在服务器上面的绝对路径
        String path = context.getRealPath("/file/config.properties");
        System.out.println("path=" + path);
        
        // 创建属性对象
        Properties properties = new Properties();

        // 指定载入的数据源
        InputStream is = new FileInputStream(path);
        properties.load(is);

        // 获取属性的值
        String name = properties.getProperty("name");
        System.out.println("name=" + name);
    }

    
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}
效果 效果 
package com.dashucoding.servlet;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class Demo03
 */
public class Demo03 extends HttpServlet {
    
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
//      test01();
//      test02();
        test03();
    }
    private void test03() {
        // TODO Auto-generated method stub
        try {
            // 获取ServletContext对象
            ServletContext context = getServletContext();
            
            // 创建属性对象
            Properties properties = new Properties();

            // 指定载入的数据源
            InputStream is = getClass().getClassLoader().getResourceAsStream("../../file/config.properties");
            properties.load(is);

            // 获取属性的值
            String name = properties.getProperty("name");
            System.out.println("name02=" + name);
            is.close();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    // alt + shift + z
    private void test02() {
        try {
            // 获取ServletContext对象
            ServletContext context = getServletContext();
            
            // 创建属性对象
            Properties properties = new Properties();

            // 指定载入的数据源
            InputStream is = context.getResourceAsStream("/file/config.properties");
            properties.load(is);

            // 获取属性的值
            String name = properties.getProperty("name");
            System.out.println("name02=" + name);
            is.close();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    // alt + shift + m
    private void test01() throws FileNotFoundException, IOException {
        // 获取ServletContext对象
        ServletContext context = getServletContext();
        // 获取给定的文件在服务器上面的绝对路径
        String path = context.getRealPath("/file/config.properties");
        System.out.println("path=" + path);
        
        // 创建属性对象
        Properties properties = new Properties();

        // 指定载入的数据源
        InputStream is = new FileInputStream(path);
        properties.load(is);

        // 获取属性的值
        String name = properties.getProperty("name");
        System.out.println("name=" + name);
    }

    
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}
效果

ServletContext可以获取全局配置参数，可以获取web工程中的资源，存储数据，servlet简共享数据。

使用ServletContext获取数据

效果 
package com.dashucoding.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class LoginServlet
 */
public class LoginServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 别人把数据给你了,你就要进行获取数据
        
        String userName = request.getParameter("username");
        String password = request.getParameter("password");
        System.out.println("usrName=" + userName + "==password==" + password );
        // 校验数据
        
        if("dashu".equals(userName)&&"123".equals(password)) {
            System.out.println("登录成功");
        }else {
            System.out.println("登录失败");
        }
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
    <h2>登录</h2>
    
    
    <form action="LoginServlet" method="get">
        账号:<input type="text" name="username"/><br>
        密码:<input type="text" name="password"/><br>
        <input type="submit" value="登录"/>
    </form>
</body>
</html>
效果 效果 效果 效果 效果

登录

package com.dashucoding.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class LoginServlet
 */
public class LoginServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 别人把数据给你了,你就要进行获取数据
        
        String userName = request.getParameter("username");
        String password = request.getParameter("password");
        System.out.println("usrName=" + userName + "==password==" + password );
        // 校验数据
        // response
        
        PrintWriter pw = response.getWriter();
        
        if("dashu".equals(userName)&&"123".equals(password)) {
            // System.out.println("登录成功");
            pw.write("login success");
        }else {
            // System.out.println("登录失败");
            pw.write("login failed");
        }
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}
效果 效果 效果 
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
    <h2>登录成功</h2>
    <a href="CountSrevlet">获取网站登录成功总数 </a>
</body>
</html>

package com.dashucoding.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class LoginServlet
 */
public class LoginServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 别人把数据给你了,你就要进行获取数据
        
        String userName = request.getParameter("username");
        String password = request.getParameter("password");
        System.out.println("usrName=" + userName + "==password==" + password );
        // 校验数据
        // response
        
        PrintWriter pw = response.getWriter();
        
        if("dashu".equals(userName)&&"123".equals(password)) {
            // System.out.println("登录成功");
            // pw.write("login success");
            // 成功跳转 login_success.html
            // 设置状态码
            response.setStatus(302);
            response.setHeader("Location", "login_success.html");
        }else {
            // System.out.println("登录失败");
            pw.write("login failed");
        }
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

登录次数

效果 
package com.dashucoding.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class CountServlet
 */
public class CountServlet extends HttpServlet {
    
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 取值
        int count = (int)getServletContext().getAttribute("count");
        
        // 输出界面
        response.getWriter().write("login success count == "+count);
    }


    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

package com.dashucoding.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class LoginServlet
 */
public class LoginServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 别人把数据给你了,你就要进行获取数据
        
        String userName = request.getParameter("username");
        String password = request.getParameter("password");
        System.out.println("usrName=" + userName + "==password==" + password );
        // 校验数据
        // response
        
        PrintWriter pw = response.getWriter();
        
        if("dashu".equals(userName)&&"123".equals(password)) {
            // System.out.println("登录成功");
            // pw.write("login success");
            // 成功跳转 login_success.html
            // 成功次数累加 存东西
            
            
            // 获取以前旧的值,然后给它赋新值
            Object obj = getServletContext().getAttribute("count");
            
            int totalCount = 0;
            
            if(obj != null) {
                totalCount = (int)obj;
            }
            
            System.out.println("登录成功的此时是" + totalCount);
        
            // 给count赋新值 set add put
            getServletContext().setAttribute("count",totalCount+1);

            
            // 设置状态码
            response.setStatus(302);
            response.setHeader("Location", "login_success.html");
        }else {
            // System.out.println("登录失败");
            pw.write("login failed");
        }
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
    <h2>登录成功</h2>
    <a href="CountServlet">获取网站登录成功总数 </a>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
    <h2>登录</h2>
    
    
    <form action="LoginServlet" method="get">
        账号:<input type="text" name="username"/><br>
        密码:<input type="text" name="password"/><br>
        <input type="submit" value="登录"/>
    </form>
</body>
</html>
效果 效果

路径：

    <form action="login" method="get">
        账号:<input type="text" name="username"/><br>
        密码:<input type="text" name="password"/><br>
        <input type="submit" value="登录"/>
    </form>

  <servlet-mapping>
    <servlet-name>LoginServlet</servlet-name>
    <url-pattern>/login</url-pattern>
  </servlet-mapping>

// ServletContext 销毁，服务器移除，关闭服务器
只要同一个应用程序就行

作用：

  1. 获取全局配置
  2. 获取web工程中的资源
  3. 存储数据
  4. 共享数据

HttpServletRequest获取请求头

获取所有的头信息:

package com.dashucoding.servlet;

import java.io.IOException;
import java.util.Enumeration;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class Demo01
 */
public class Demo01 extends HttpServlet {
    
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        // request封装了客户端提交过来的一切数据
        // 拿所有的头 得到一个枚举 List集合
        Enumeration<String> headerNames = request.getHeaderNames();
        while(headerNames.hasMoreElements()) {
            String name = (String) headerNames.nextElement();
            System.out.println("name=" + name);
        }
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}
效果 效果

得到所有

package com.dashucoding.servlet;

import java.io.IOException;
import java.util.Enumeration;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class Demo01
 */
public class Demo01 extends HttpServlet {
    
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        // request封装了客户端提交过来的一切数据
        // 拿所有的头 得到一个枚举 List集合
        Enumeration<String> headerNames = request.getHeaderNames();
        while(headerNames.hasMoreElements()) {
            String name = (String) headerNames.nextElement();
            String value = request.getHeader(name);
            System.out.println("name=" + name + ";value=" + value);
        }
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}
效果

获取提交的信息

package com.dashucoding.servlet;

import java.io.IOException;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class Demo01
 */
public class Demo01 extends HttpServlet {
    
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        // request封装了客户端提交过来的一切数据
        // 拿所有的头 得到一个枚举 List集合
        Enumeration<String> headerNames = request.getHeaderNames();
        while(headerNames.hasMoreElements()) {
            String name = (String) headerNames.nextElement();
            String value = request.getHeader(name);
            System.out.println("name=" + name + ";value=" + value);
        }
        
        System.out.println("----------");
        
        // 请求体，拼接过来的数据 获取客户端提交过来的数据
        String name = request.getParameter("name");

        System.out.println("name=" + name);
        // http://localhost:8080/RequestDemo01/Demo01?name=dashucoding
        // http://localhost:8080/RequestDemo01/Demo01?name=dashucoding&address=GD
        
        System.out.println("----------");
        // 获取所有参数
        // Enumeration<String> parameterNames = request.getParameterNames();
        
        Map<String, String[]> map = request.getParameterMap();
        
        Set<String> keySet = map.keySet();
        Iterator<String> iterator = keySet.iterator();
        while(iterator.hasNext()) {
            String key = (String) iterator.next();
            System.out.println("key="+key+"，的值总数" + map.get(key).length);
            String value = map.get(key)[0];
            String value1 = map.get(key)[1];
            String value2 = map.get(key)[2];
            
            System.out.println(key+" == "+value + "=" + value1 + "=" + value2);
            // http://localhost:8080/RequestDemo01/Demo01?name=dashucoding&address=GD
            // name=zhangsan&name=lisi
        }
        
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

如果看了觉得不错

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达叔小生：往后余生，唯独有你
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90后帅气小伙，良好的开发习惯；独立思考的能力；主动并且善于沟通
简书博客： 达叔小生
https://www.jianshu.com/u/c785ece603d1

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