Servlet--request

tomcat:

Servlet:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">



    <!--配置Servlet-->
    <servlet>
        <servlet-name>demo1</servlet-name>
        <servlet-class>servlet.ServletDemo1</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>demo1</servlet-name>
        <url-pattern>/demo1</url-pattern>
    </servlet-mapping>

    <!--配置Servlet-->
    <servlet>
        <servlet-name>demo2</servlet-name>
        <servlet-class>servlet.ServletDemo2</servlet-class>
        <!--指定Servlet的创建时机
            1.第一次被访问时,创建
                *<load-on-startup>的值为负数
            2.在服务器启动时,创建
              *<load-on-startup>的值为非负数
        -->

        <load-on-startup>-5</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>demo2</servlet-name>
        <url-pattern>/demo2</url-pattern>
    </servlet-mapping>
</web-app>

package requset;

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

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: ${PACKAGE_NAME}
 * @ClassName: ${NAME}
 * @Author: 王团结
 * @Description: 演示request对象获取请求行数据
 * @Date: 2019/6/22 0:24
 * @Version: 1.0
 */
@WebServlet("/requestDemo1")
public class RequestDemo1 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        System.out.println(request.getMethod());
        System.out.println(request.getContextPath());
        System.out.println(request.getServletPath());
        System.out.println(request.getQueryString());
        System.out.println(request.getRequestURI());
        System.out.println(request.getRequestURL());
        System.out.println(request.getProtocol());
        System.out.println(request.getRemoteAddr());
    }
}

package requset;

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

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: ${PACKAGE_NAME}
 * @ClassName: ${NAME}
 * @Author: 王团结
 * @Description: ${description}
 * @Date: 2019/6/22 0:40
 * @Version: 1.0
 */
@WebServlet("/requestDemo2")
public class RequestDemo2 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //演示获取请求头数据

        //1.获取所有请求头名称
        Enumeration<String> headerNames=request.getHeaderNames();
        //2.遍历
        while (headerNames.hasMoreElements()) {
            String name=headerNames.nextElement();
            //根据名称获取请求头的值
            String value=request.getHeader(name);
            System.out.println(name+"--"+value);
        }
    }
}

package requset;

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

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: ${PACKAGE_NAME}
 * @ClassName: ${NAME}
 * @Author: 王团结
 * @Description: ${description}
 * @Date: 2019/6/22 0:40
 * @Version: 1.0
 */
@WebServlet("/requestDemo3")
public class RequestDemo3 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //演示获取请求头数据
        String referer=request.getHeader("referer");
        System.out.println(referer);


        //防盗链
        if (referer != null) {
            if(referer.contains("/test")){
                System.out.println("正常");
                response.setContentType("text/html;charset=utf-8");
                response.getWriter().write("欢迎");

            }else{
                System.out.println("盗链");
            }
        }
    }
}

package requset;

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

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: ${PACKAGE_NAME}
 * @ClassName: ${NAME}
 * @Author: 王团结
 * @Description: ${description}
 * @Date: 2019/6/22 0:40
 * @Version: 1.0
 */
@WebServlet("/requestDemo4")
public class RequestDemo4 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //演示获取请求头数据

       String agent=request.getHeader("user-agent");
       //判断agent的浏览器版本
        if(agent.contains("Chrome")){
            System.out.println("谷歌");
        }else if(agent.contains("Firofox")){
            System.out.println("火狐");
        }
    }
}

package requset;

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

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: ${PACKAGE_NAME}
 * @ClassName: ${NAME}
 * @Author: 王团结
 * @Description: ${description}
 * @Date: 2019/6/22 7:44
 * @Version: 1.0
 */
@WebServlet("/RequestDemo5")
public class RequestDemo5 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取请求消息体--请求参数

        //1.获取字符流
        BufferedReader br=request.getReader();
        //2.读取数据
        String line =null;
        while ((line = br.readLine()) != null) {
            System.out.println(line);
        }

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }
}

package requset;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Map;
import java.util.Set;

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: ${PACKAGE_NAME}
 * @ClassName: ${NAME}
 * @Author: 王团结
 * @Description: ${description}
 * @Date: 2019/6/22 7:44
 * @Version: 1.0
 */
@WebServlet("/RequestDemo6")
public class RequestDemo6 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //post获取请求参数

        //  根据参数名称获取参数值
        String username = request.getParameter("username");
        System.out.println("post:" + username);

        //根据参数名称获取参数值的数组
        String[] hobbies = request.getParameterValues("hobby");
        for (String hobby :hobbies) {
            System.out.println(hobby);
        }

        //获取所有请求的参数名称

        Enumeration<String > perarametNames=request.getParameterNames();
        while (perarametNames.hasMoreElements()) {

            String name=perarametNames.nextElement();
            System.out.println(name);
            String value=request.getParameter(name);
            System.out.println(value);
            System.out.println("-----------");
        }

        //获取所有参数的集合
        Map<String,String[]> parameterMpa=request.getParameterMap();
        //遍历
        Set<String> keyset=parameterMpa.keySet();
        for(String name:keyset){
            //通过键得值
            String[] values=parameterMpa.get(name);
            for (String value:values) {
                System.out.println(value);
            }
            System.out.println("-----------------");
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //get 获取请求参数

        /*//  根据参数名称获取参数值
        String username = request.getParameter("username");
        System.out.println("get:" + username);*/

        this.doPost(request,response);
    }
}

package requset;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Map;
import java.util.Set;

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: ${PACKAGE_NAME}
 * @ClassName: ${NAME}
 * @Author: 王团结
 * @Description: ${description}
 * @Date: 2019/6/22 7:44
 * @Version: 1.0
 */
@WebServlet("/RequestDemo7")
public class RequestDemo7 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.设置流的编码

        request.setCharacterEncoding("utf-8");
        //获取请求参数username
        String username=request.getParameter("username");
        System.out.println(username);


    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //get 获取请求参数

        this.doPost(request,response);
    }
}

package requset;

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

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: ${PACKAGE_NAME}
 * @ClassName: ${NAME}
 * @Author: 王团结
 * @Description: ${description}
 * @Date: 2019/6/22 7:44
 * @Version: 1.0
 */
@WebServlet("/RequestDemo8")
public class RequestDemo8 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("demo8");

        //存储数据到request
        request.setAttribute("msg","hello");
       request.getRequestDispatcher("/RequestDemo9").forward(request,response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //get 获取请求参数

        this.doPost(request,response);
    }
}

package requset;

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

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: ${PACKAGE_NAME}
 * @ClassName: ${NAME}
 * @Author: 王团结
 * @Description: ${description}
 * @Date: 2019/6/22 7:44
 * @Version: 1.0
 */
@WebServlet("/RequestDemo9")
public class RequestDemo9 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println(request.getAttribute("msg"));
        System.out.println("demo9");

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //get 获取请求参数

        this.doPost(request,response);
    }
}

package requset;

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

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: ${PACKAGE_NAME}
 * @ClassName: ${NAME}
 * @Author: 王团结
 * @Description: ${description}
 * @Date: 2019/6/22 7:44
 * @Version: 1.0
 */
@WebServlet("/RequestDemo10")
public class RequestDemo10 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ServletContext servletContext = request.getServletContext();
        System.out.println(servletContext);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //get 获取请求参数

        this.doPost(request,response);
    }
}

package servlet;

import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebServlet;
import java.io.IOException;

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: servlet
 * @ClassName: ServeltDemo3
 * @Author: 王团结
 * @Description:
 * @Date: 2019/6/21 22:08
 * @Version: 1.0
 */
@WebServlet("/demo3")
public class ServeltDemo3 extends GenericServlet {
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("demo3...");
    }
}

package servlet;

import javax.servlet.*;
import javax.servlet.annotation.WebServlet;
import java.io.IOException;

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: servlet
 * @ClassName: ServlDemo
 * @Author: 王团结
 * @Description: 不用配置的注解
 * @Date: 2019/6/21 21:29
 * @Version: 1.0
 */

@WebServlet(urlPatterns = "/demo2")
public class ServletDemo implements Servlet {
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {

    }

    @Override
    public ServletConfig getServletConfig() {
        return null;
    }

    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("hello");
    }

    @Override
    public String getServletInfo() {
        return null;
    }

    @Override
    public void destroy() {

    }
}

package servlet;

import javax.servlet.*;
import javax.servlet.annotation.WebServlet;
import java.io.IOException;

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: cn.king.web.servlet
 * @ClassName: ServletDemo1
 * @Author: ASUS
 * @Description: Servlet快速入门
 * @Date: 2019/6/21 18:21
 * @Version: 1.0
 */
@WebServlet("/demo1")
public class ServletDemo1 implements Servlet {
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {

    }

    @Override
    public ServletConfig getServletConfig() {
        return null;
    }

    //提供服务的方法
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("hello Servlet");
    }

    @Override
    public String getServletInfo() {
        return null;
    }

    @Override
    public void destroy() {

    }
}

package servlet;

import javax.servlet.*;
import java.io.IOException;

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: cn.king.web.servlet
 * @ClassName: ServletDemo2
 * @Author: ASUS
 * @Description: Servlet方法
 * @Date: 2019/6/21 19:28
 * @Version: 1.0
 */
public class ServletDemo2 implements Servlet {

    /**
     *  初始化方法
     *  在Servlet被创建时,执行.只会执行一次
     * @param servletConfig
     * @throws ServletException
     */
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
        System.out.println("init..........");
    }

    /**
     * 获取ServletConfig对象
     * ervletConfig是Servlet的配置对象
     * @return
     */
    @Override
    public ServletConfig getServletConfig() {
        return null;
    }

    /**
     * 提供服务方法
     * 每一次Servlet被访问时,执行.执行多次
     * @param servletRequest
     * @param servletResponse
     * @throws ServletException
     * @throws IOException
     */
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("service..");
    }

    /**
     * 获取Servlet的一些信息,版本,作者信息等等
     * @return
     */
    @Override
    public String getServletInfo() {
        return null;
    }

    /**
     * 销毁方法
     * 在服务器正常关闭时,执行.执行一次.
     */
    @Override
    public void destroy() {
        System.out.println("destroy");
    }
}

package servlet;

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

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: servlet
 * @ClassName: ServletDemo4
 * @Author: 王团结
 * @Description:
 * @Date: 2019/6/21 22:23
 * @Version: 1.0
 */
@WebServlet("/demo4")
public class ServletDemo4 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("doGET");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("doPOST ");
    }
}

package servlet;

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

/**
 * @ProjectName: TutorDualSelectionSystem
 * @Package: servlet
 * @ClassName: ServletDemo5
 * @Author: 王团结
 * @Description: Serlet路径配置
 * @Date: 2019/6/21 22:39
 * @Version: 1.0
 */
//@WebServlet({"/d4", "/user/dd4", "/user/ddd4/*"})
    @WebServlet({"/d4", "/user/dd4"})
public class ServletDemo5 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("demo5");
    }
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/test/demo4" method="post">
    <input name="username">
    <input type="submit" value="提交2">
</form>
<a href="/test/requestDemo3">demo4</a>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>注册页面</title>
</head>
<body>

    <form action="/test/RequestDemo5" method="post">
        <input type="text" placeholder="请输入用户名" name="usename"><br>
        <input type="text" placeholder="请输入密码" name="password"><br>
        <input type="submit" value="注册">

    </form>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>注册页面</title>
</head>
<body>

    <form action="/test/RequestDemo7" method="get">
        <input type="text" placeholder="请输入用户名" name="username"><br>
        <input type="text" placeholder="请输入密码" name="password"><br>

        <input type="checkbox" name="hobby" value="game">游戏
        <input type="checkbox" name="hobby" value="study">学习
        <br>
        <input type="submit" value="注册">

    </form>
</body>
</html>

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原文地址：https://www.cnblogs.com/King-boy/p/11066855.html