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java web多组件协作实现用户登录验证

实现步骤：

1、创建用户登录提交界面

2、创建处理用户登录请求servlet组件Main

3、创建代表登录成功响应的servlet的组件LoginSuccess

4、创建代表登录失败响应的servlet组件LoginFail

【1代码login.html】

<!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</title>
</head>
<body bgcolor="#FFFFFF">
    <center>欢迎登录系统</center>
    <form name="login" action="Main" method="post">
        <label>用户名：</label>
        <input type="text" name="userID" value="">
        <label>密码：</label>
        <input type="password" name="password" value="">
        <input type="submit"  name="tj" value="提交"></input>
        <input type="reset" name="reset"></input>
    
    </form>
</body>
</html>

【2程序Main.java】

package example.servlet;

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 Main
 */
@WebServlet("/Main")
public class Main extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            String uerID=request.getParameter("userID");
            if (uerID==null) uerID="";
            String password=request.getParameter("password");
            if(password==null) password="";
            if(uerID.equals("guest")&&password.equals("guest")){
                RequestDispatcher dispatcher=request.getRequestDispatcher("LoginSuccess");
                dispatcher.forward(request, response);
            }else {
                RequestDispatcher dispatcher=request.getRequestDispatcher("LoginFail");
                dispatcher.forward(request, response);
            }
    }


    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        processRequest(request,response);
    }


    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        processRequest(request,response);
    }
    
    public String getServletinfo(){
        return "short description";
    }

}

【3程序LoginSuccess.java】

package example.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/LoginSuccess")
public class LoginSuccess extends HttpServlet {
    private static final long serialVersionUID = 1L;
    
    protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html; charset=UTF-8");
        PrintWriter out=response.getWriter();
        String name=request.getParameter("userID");
        
        out.println("<html>");
        out.println("<head>");
        out.println("<title>登录成功</title>");
        out.println("</head>");
        out.println("<body>");
        out.println("<h1>欢迎"+name+"您已成功登录系统</h1>");
        out.println("</body>");
        out.println("</html>");
        
        
        
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        processRequest(request,response);
    }


    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        processRequest(request,response);
    }
    
    public String getServletInfo(){
        return "short description";
    }

}

【4程序LoginFail.java】

package example.servlet;

import java.io.IOException;
import java.io.PrintWriter;

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 LoginFail
 */
@WebServlet("/LoginFail")
public class LoginFail extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html; charset=UTF-8");
        PrintWriter out=response.getWriter();
        
        out.print("<html>");
        out.print("<head>");
        out.print("<title>登录失败</title>");
        out.print("</head>");
        out.print("<body>");
        out.print("<h1>登录失败，请重新登录</h1>");
        RequestDispatcher dispatcher=request.getRequestDispatcher("login.html");
        dispatcher.include(request, response);
        out.print("</body>");
        out.print("<html>");
        
    }

    
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        processRequest(request,response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        processRequest(request,response);
    }
    
    public String getServletInfo(){
        return "short description";
    }

}

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原文地址：https://www.cnblogs.com/xiaoyingzhanchi/p/9098036.html