Servlet简单登陆验证实例

àì夳堔傛蜴生んèń 2021-09-10 12:26 384阅读 0赞

[林炳文Evankaka][Evankaka]原创作品。转载请注明出处[http://blog.csdn.net/evankaka][http_blog.csdn.net_evankaka]

本文要实现Servlet简单登陆验证实例。结构如下

![20150421133300089][]

1、LoginCheck.java

package com.mucfc;
    
    import java.io.IOException;
    
    import javax.servlet.RequestDispatcher;
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    /**
     * Servlet implementation class LoginCheck
     */
    @WebServlet("/LoginCheck")
    public class LoginCheck extends HttpServlet {
    	private static final long serialVersionUID = 1L;
           
        /**
         * @see HttpServlet#HttpServlet()
         */
        public LoginCheck() {
            super();
            // TODO Auto-generated constructor stub
        }
    
    	/**
    	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
    	 */
    	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		String username = request.getParameter("username");     
            String password = request.getParameter("password");        
              
            //服务器端打印信息  
            System.out.println("username=" + username);  
            System.out.println("password=" + password);  
            if(username!=null&&password!=null && username.equals("linbingwen")&&password.equals("1234")){
            	//将数据存储在request对象中，传递给下一个servlet使用
            	request.setAttribute("username", username);
            	//进行数据的转发
            	RequestDispatcher dispatcher=request.getRequestDispatcher("Welcome");
            	dispatcher.forward(request, response);
           
            }
            else {
    			response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE,"用户名或密码错误");
    		}
    	}
    
    	/**
    	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
    	 */
    	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		  doGet(request, response);    
    	}
    
    }

2、Welcome

package com.mucfc;
    
    import java.io.IOException;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    /**
     * Servlet implementation class Welcome
     */
    @WebServlet("/Welcome")
    public class Welcome extends HttpServlet {
    	private static final long serialVersionUID = 1L;
           
        /**
         * @see HttpServlet#HttpServlet()
         */
        public Welcome() {
            super();
            // TODO Auto-generated constructor stub
        }
    
    	/**
    	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
    	 */
    	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		
    		String username = request.getParameter("username");   
    		//设置编码格式  
            response.setContentType("text/html;charset=GB18030");           
            //返回html页面  
            response.getWriter().println("<html>");  
            response.getWriter().println("<head>");     
            response.getWriter().println("<title>登录信息</title>");      
            response.getWriter().println("</head>");    
            response.getWriter().println("<body algin=center>");     
            response.getWriter().println("欢迎【" + username + "】用户登录成功！！！");    
            response.getWriter().println("</body>");    
            response.getWriter().println("</html>");  
    	}
    
    	/**
    	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
    	 */
    	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		  doGet(request, response);    
    	}
    
    }

3、index.jsp

<%@ page language="java" contentType="text/html" pageEncoding="UTF-8"%>
    
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <title>登录</title>  
    </head>
    <body>
    <form action="servlet/LoginCheck" method="POST">  
                用户：<input type="text" name="username" /><br/>  
                密码：<input type="password" name="password" /><br/>  
                <input type="submit" value="登录" />           
            </form>  
    
    </body>
    </html>

4、web.xml

<?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" version="2.5">
     
      <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
      </welcome-file-list>
      
      <servlet>
        <servlet-name>LoginCheck</servlet-name>
        <servlet-class>com.mucfc.LoginCheck</servlet-class>
      </servlet>
      <servlet-mapping>
        <servlet-name>LoginCheck</servlet-name>
        <url-pattern>/servlet/LoginCheck</url-pattern>
      </servlet-mapping>
      
        <servlet>
        <servlet-name>Welcome</servlet-name>
        <servlet-class>com.mucfc.Welcome</servlet-class>
      </servlet>
      <servlet-mapping>
        <servlet-name>Welcome</servlet-name>
        <url-pattern>/servlet/Welcome</url-pattern>
      </servlet-mapping>
      
    </web-app>

运行后：

![20150421110421382][]

输入正确用户名（lingbingwen)和密码（1234）

![20150421110505577][]

输入错误

![20150421110631290][]

[  
][Evankaka]

Servlet接口定义三个实现类，分别是FacesServlet， GenericServlet， HttpServlet。下面我们简单的介绍一下。

5、Servlet接口实现类

（1）FacesServlet是一个用于管理利用JSF（JavaServer Faces）构建用户界面的web应用程序请求处理生命周期的Servlet。（FacesServletis a servlet that manages the request processing lifecycle for web applications that are utilizing JavaServer Faces to construct the user interface.），大家如果想深入的学习，可以点这里。

（2）GenericServlet是HttpServlet的父类，包含了servlet的常用方法。GenericServlet使得程序员写servlets更加简单，它提供了初始化和销毁生命周期的方法，以及实现了写日志文件的方法。

（3）HttpServlet指能够处理HTTP请求的servlet。这是开发人员在编写Servlet时，通常应继承这个类即可。

对于这三个实现类，只为大家做一个简单的介绍，如果想深入的研究，直接看API就好。

[  
][Evankaka]

[林炳文Evankaka][Evankaka]原创作品。转载请注明出处[http://blog.csdn.net/evankaka][http_blog.csdn.net_evankaka]

[Evankaka]: http://my.csdn.net/Evankaka
[http_blog.csdn.net_evankaka]: http://blog.csdn.net/evankaka
[20150421133300089]: /images/20210811/f08d04b4b0ae4d6f895ac7459d40199e.png
[20150421110421382]: /images/20210811/de2a4822802948aa83547b339f939d5a.png
[20150421110505577]: /images/20210811/c3f5d9fe41da4dd39526a6260c4d57ad.png
[20150421110631290]: /images/20210811/c293d93e7c464678a5c4633e4fde91d8.png