Javaweb入门之servlet（3）请求和响应

最新推荐文章于 2022-05-10 17:26:47 发布

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最新推荐文章于 2022-05-10 17:26:47 发布

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分类专栏： Java基础文章标签： java servlet

本文链接：https://blog.csdn.net/qq_45020745/article/details/107702935

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ServletTest01

package com.bky.dto;

import javax.servlet.*;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

public class ServletTest01 implements Servlet {
    public ServletTest01() {
        System.out.println("1.执行了构造方法");
    }

    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
        System.out.println("2.servlet启动");
        //servletConfig.getServletName();获取的时配置文件的别名
        String servletName = servletConfig.getServletName();
        System.out.println(servletName);


        //<init-param> 根据key获取值  只可以在一个类中使用
        String username = servletConfig.getInitParameter("username");
        System.out.println(username);

        //域对象(像map一样存取值) 设置的值在整个web工程里面都可以访问到
        ServletContext servletContext = servletConfig.getServletContext();

        servletContext.setAttribute("aaa","bbb");
        String realPath = servletContext.getRealPath("/");
        System.out.println(realPath);



    }

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

    /**
     *service 主要是处理浏览器和服务器之间的请求和响应
     * 请求 Request
     * 响应 Response
     */
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("3.执行service方法");
        HttpServletRequest httpServlet= (HttpServletRequest)servletRequest;
        String method =httpServlet.getMethod();
        //是在HttpServletRequest里面的方法
        //可以获取到浏览器具体的提交类型
        if(method.equals("GET")){
            doGet(servletRequest,servletResponse);
        }else if(method.equals("POST")){
            doPost(servletRequest,servletResponse);
        }
    }
    public void doGet(ServletRequest servletRequest, ServletResponse servletResponse){
        //只能传递一个
        String username = servletRequest.getParameter("username");
        System.out.println(username);
        System.out.println("处理get请求");
        //能够传递所有
        String[] usernames = servletRequest.getParameterValues("username");
        for (String s:usernames ) {
            System.out.println(s);
        }
    }
    public void doPost(ServletRequest servletRequest, ServletResponse servletResponse){
        System.out.println("处理post请求");
    }

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

    @Override
    public void destroy() {
        System.out.println("4.执行销毁方法（在tomcat关闭时）");
    }
}

test.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>get请求提交数据</title>
</head>
<body>
<form action="http://localhost:8899/ServletTest01" method="get">
    <input type="hidden" name="username" value="bky">
    <input type="hidden" name="username" value="bky1">
    <input type="hidden" name="username" value="bky2">
<input type="submit"/>
</form>
</body>
</html>

web.xml

<?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">


    <servlet>
        <servlet-name>ServletTest01</servlet-name>
        <servlet-class>com.bky.dto.ServletTest01</servlet-class>

        <init-param>
            <param-name>username</param-name>
            <param-value>bky</param-value>
        </init-param>

    </servlet>

    <servlet-mapping>
        <servlet-name>ServletTest01</servlet-name>
        <url-pattern>/ServletTest01</url-pattern>
    </servlet-mapping>

    <servlet>
        <servlet-name>ServletTest02</servlet-name>
        <servlet-class>com.bky.dto.ServletTest02</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>ServletTest02</servlet-name>
        <url-pattern>/ServletTest02</url-pattern>
    </servlet-mapping>


</web-app>