(一)创建登录页面
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="/Project01/LoginServlet" method="post">
用户名：<input name="username" type="text"><br/><br/>
密 码：<input name="password" type="password"><br/><br/>
<input type="submit" value="提交">
</form>
</body>
</html>(二)使用HttpServletRequest对象处理登陆数据
package com.Test;
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;
//此类处理login.html表单提交
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
String username=request.getParameter("username");
String password=request.getParameter("password");
PrintWriter out=response.getWriter();
//1.把账号、密码分别设置为root、123
if(username.equals("root")&&password.equals("123")){
//2.创建User对象保存账号、密码
User user=new User();
user.setUsername(username);
user.setPassword(password);
//3.创建Session对象保存User对象
request.getSession().setAttribute("user", user);
//4.登陆成功跳转指定页面
response.sendRedirect("/Project01/IndexServlet");
}
else{
out.println("账号或密码错误，请从新输入....");
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
(三)验证登录成功跳转到IndexServlet类
package com.Test;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
//1.创建IndexServlet显示网站的首界面
public class IndexServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//2.response解决乱码问题
response.setContentType("text/html;charset=utf-8");
//3.创建Session对象保存用户信息
HttpSession session=request.getSession();
//4.方法体中的参数要与setAttribute()键一致
User user=(User) session.getAttribute("user");
if(user==null){
response.getWriter().print("您还未登陆，请<a href='/Project01/login.html'>登陆</a>");
}else{
response.getWriter().print("您已登陆，欢迎您 "+user.getUsername());
response.getWriter().print("<a href='/Project01/LogoutServlet'>退出</a>");
//5.创建Cookie对象用来保存Session的id
Cookie cookie=new Cookie("JSESSIONID",session.getId());
cookie.setMaxAge(30*60);
cookie.setPath("/Project01");
response.addCookie(cookie);
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
(四)LogoutServlet 类用于完成用户注销
package com.Test;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//此类用于处理用户注销
public class LogoutServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1.Session对象删除保存User对象
request.getSession().removeAttribute("user");
response.sendRedirect("/Project01/IndexServlet");
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
(五)配置各个Servlet类
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<display-name>Project01</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
</welcome-file-list>
<servlet>
<description></description>
<display-name>IndexServlet</display-name>
<servlet-name>IndexServlet</servlet-name>
<servlet-class>com.Test.IndexServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>IndexServlet</servlet-name>
<url-pattern>/IndexServlet</url-pattern>
</servlet-mapping>
<servlet>
<description></description>
<display-name>LoginServlet</display-name>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>com.Test.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/LoginServlet</url-pattern>
</servlet-mapping>
<servlet>
<description></description>
<display-name>LogoutServlet</display-name>
<servlet-name>LogoutServlet</servlet-name>
<servlet-class>com.Test.LogoutServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LogoutServlet</servlet-name>
<url-pattern>/LogoutServlet</url-pattern>
</servlet-mapping>
</web-app>结果演示：
