JavaWeb之Servlet编程实例二

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使用Servlet可以读取用户输入的信息并跳转页面显示出来，代码如下:

LoginServlet代码：

package com.djx.sevlet;import java.io.IOException;import javax.servlet.RequestDispatcher;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.sun.net.httpserver.HttpServer;import com.sun.net.httpserver.HttpsServer;import sun.security.krb5.internal.SeqNumber;public class LoginServlet extends HttpServlet{/** *  */private static final long serialVersionUID = 1L;/*@Overrideprotected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// TODO Auto-generated method stubString username=req.getParameter("uname");String upassword=req.getParameter("upwd");System.out.println("用户名："+username);System.out.println("密码："+upassword);//super.service(req, resp);}*/@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// TODO Auto-generated method stubSystem.out.println("进入doGet方法");doPost(req, resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// TODO Auto-generated method stubSystem.out.println("进入doPost方法");String username=req.getParameter("uname");String upassword=req.getParameter("upwd");System.out.println("用户名："+username);System.out.println("密码："+upassword);String forward=null;if (username=="djx" && upassword=="123") {//请求重定向//resp.sendRedirect(req.getContextPath()+"/15/success.jsp");forward="/15/success.jsp";RequestDispatcher rd=req.getRequestDispatcher(forward);rd.forward(req, resp);}else{//resp.sendRedirect(req.getContextPath()+"/15/error.jsp");forward="/15/success.jsp";RequestDispatcher rd=req.getRequestDispatcher(forward);rd.forward(req, resp);}//super.doPost(req, resp);}}

<%@ page language="java" contentType="text/html; charset=utf-8"    pageEncoding="utf-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>Insert title here</title></head><body><form action="<%=request.getContextPath()%>/LoginServlet" method="post">用户名：<input type="text" name="uname"><br/>密 码：<input type="password" name="upwd"><br/><input type="submit" value="提交"><input type="reset" value="重置"></form></body></html>

success.js代码如下：

<%@ page language="java" contentType="text/html; charset=utf-8"    pageEncoding="utf-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>登录成功页面提示</title></head><body>登陆成功。<br/>您提交的信息为：<br/>用户名：<%=request.getParameter("uname") %><br/>密码：<%=request.getParameter("upwd") %><br/><a href="login.jsp">返回登录页面</a></body></html>

error.jsp代码：

<%@ page language="java" contentType="text/html; charset=utf-8"    pageEncoding="utf-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>登录失败提示</title></head><body>登陆失败。<br/>您提交的信息为：<br/>用户名：<%=request.getParameter("uname") %><br/>密码：<%=request.getParameter("upwd") %><br/><a href="login.jsp">返回登录页面</a></body></html>

在xml文件加入如下代码：

<servlet>  <servlet-name>LoginServlet</servlet-name>  <servlet-class>com.djx.sevlet.LoginServlet</servlet-class> </servlet><servlet-mapping>  <servlet-name>LoginServlet</servlet-name>  <url-pattern>/LoginServlet</url-pattern>  </servlet-mapping>

使用response对象的请求重定向虽然能够成功跳转页面但是并不能显示输入的信息，但是使用请求转发就可以成功跳转并输出信息。请求转发只能在相同组件间跳转，但是请求重定向却可以在不同组件间跳转。

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