JavaWeb-----ServletRequest、ServletResponse和HttpServletRequest、HttpServletResponse

JSP页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
    <form action="${pageContext.request.contextPath}/login" method="post">
        <span>用户名：</span><input type="text" name="userName"> <span>密码：</span><input
            type="text" name="userPwd"> <input type="submit" value="提交">
    </form>
</body>
</html>

Web.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://xmlns.jcp.org/xml/ns/javaee"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
    id="WebApp_ID" version="3.1">
    <display-name>JspAndServlet</display-name>
    <welcome-file-list>
        <welcome-file>login.jsp</welcome-file>
    </welcome-file-list>

    <servlet>
        <servlet-name>loginServlet</servlet-name>
        <servlet-class>com.servlet.LoginServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>loginServlet</servlet-name>
        <url-pattern>/login</url-pattern>
    </servlet-mapping>
</web-app>

1. ServletRequest、ServletResponse

Servlet类实现Servlet接口

ServletRequest: 封装了请求信息. 可以从中获取到任何的请求信息
ServletResponse: 封装了响应信息, 如果想给用户什么响应, 具体可以使用该接口的方法实现

package com.servlet;

import java.io.IOException;

import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 实现Servlet接口
 * 
 * @author yyx 2019年9月1日
 */
public class LoginServlet implements Servlet {

    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse)
            throws ServletException, IOException {
        // servletRequest需要强制转换成HttpServletRequest才能获取Http相关信息
        HttpServletRequest req = (HttpServletRequest) servletRequest;

        String userName = req.getParameter("userName");
        String userPwd = req.getParameter("userPwd");
        System.out.println(userName + " " + userPwd);

        String requestURI = req.getRequestURI();
        System.out.println(requestURI);

        String method = req.getMethod();
        System.out.println(method);

        String queryString = req.getQueryString();
        System.out.println(queryString);

        String servletPath = req.getServletPath();
        System.out.println(servletPath);

        // 设置响应的内容类型
        HttpServletResponse resp = (HttpServletResponse) servletResponse;
        resp.setCharacterEncoding("UTF-8");

    }

    @Override
    public void destroy() {

    }

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

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

    @Override
    public void init(ServletConfig arg0) throws ServletException {

    }

}

2. HttpServletRequest、HttpServletResponse

Servlet类实现继承HttpServlet

HttpServletRequest继承自ServletRequest
HttpServletResponse继承自ServletResponse

package com.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
 * 继承HttpServlet类
 * @author yyx 2019年9月1日
 */
public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String userName=req.getParameter("userName");
        String userPwd=req.getParameter("userPwd");
        System.out.println(userName+" "+userPwd);
        
        String requestURI = req.getRequestURI();
        System.out.println(requestURI);
        
        String method = req.getMethod();
        System.out.println(method); 
        
        String queryString = req.getQueryString();
        System.out.println(queryString); 
        
        String servletPath = req.getServletPath();
        System.out.println(servletPath); 
        
        //设置响应的内容类型
        resp.setCharacterEncoding("UTF-8");
    }

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

}