jsp使用Servlet实现用户登录功能李老师实验7-1

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实验总结：

在login.java中有个判断语句，它通把login.html前端表单提交过来的账号密码与在web.xml中提取的账号和密码作比较，如果账号密码都相同则通过审核，执行请求转发跳转到welcome.jsp显示welcome,用户名（其中用户名动态传参显示），若不相同则执行重定向跳转到error.jsp显示登陆失败点击重新登录回到login.html

关键知识：

请求转发：request.getRequestDispatcher("/welcome.jsp").forward(request, response);
重定向：response.sendRedirect("/ping17180074/error.jsp");
请求转发跳转规则地址栏url不变
重定向跳转地址url改变

效果预览：

1.输入错误账号密码时

2.输入正确账号密码时

视频步骤：（3分钟）

文章底部可下载完整代码带现成实验模板

实验代码：

代码中学号姓名记得删改！！！

login.html文件(位置：根目录/WebRoot/）

<!DOCTYPE html>
<html>
  <body>
    <form action="servlet/login" method="post">
输入账号：<input type="text" name="user">
<br>
<br>
输入密码：<input type="password" name="pwd">
<br>
<br>
    <input type="submit" value="登录">
    </form>
  </body>
</html>

login.java文件(位置：根目录/src/servlet/）

package 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;

public class login extends HttpServlet {

    /**17180074平帅
     * 
     */
    private static final long serialVersionUID = 618236416112505770L;

    public void doPost(HttpServletRequest request,HttpServletResponse response)
            throws ServletException, IOException {
        //获得初始化参数
        String ouserName=this.getInitParameter("ouserName");
        String ouserPwd=this.getInitParameter("ouserPwd");
        //从request接收表单数据
        request.setCharacterEncoding("GBK");
        String name=request.getParameter("user");
        String pass=request.getParameter("pwd");
        //通过response向客户端应答，显示接收到的数据
        response.setContentType("text/html;charset=GBK");
        PrintWriter out = response.getWriter();
        out.println("<HTML>");
        out.println("<HEAD><TITLE>处理表单</TITLE></HEAD>");
        out.println("<BODY>");
        if(name.equals(ouserName)&&pass.equals(ouserPwd)){
            request.getRequestDispatcher("/welcome.jsp").forward(request, response);//请求转发跳转
        }else{
            response.sendRedirect("/ping17180074/error.jsp");//重定向跳转
        }
        out.println("</BODY>");
        out.println("</HTML>");
        out.flush();
        out.close();
        }
    }

welcome.jsp文件(位置：根目录/WebRoot/）

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>welcome</title>
</head>
<body>
    <%
       request.setCharacterEncoding("utf-8");
       String name=request.getParameter("user");

     %>
   welcome,<%=name %><br>
</body>
</html>

error.jsp文件(位置：根目录/WebRoot/）

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>errorpage</title>
</head>
<body>
    登录失败，请重新<a href="<%=request.getContextPath()%>/login.html">登录</a>
</body>
</html>

web.xml文件(位置：根目录/WebRoot/WEB-INF/）

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <servlet>

  <description>This is the description of my J2EE component</description>
  <display-name>This is the display name of my J2EE component</display-name>

  <servlet-name>register</servlet-name>
  <servlet-class>servlet.register</servlet-class>

</servlet>

     <servlet>

  <servlet-name>login</servlet-name>
  <servlet-class>servlet.login</servlet-class>
  <init-param>
  <param-name>ouserName</param-name>
  <param-value>17180074</param-value>
  </init-param>
  <init-param>
  <param-name>ouserPwd</param-name>
  <param-value>123456</param-value>
  </init-param>

  </servlet>

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

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

  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>

</web-app>