servlet实现登陆注册

拿到信息必须进行非空验证
用servlet做注册登陆时，在form表单的action中不用加后缀.java,jsp文件需要加

public boolean CheckParm(String...args){
        for(String s:args){
            if("".equals(s)||s==null){
                return false;
            }
        }
        
        return true;
        
    }

当不确定传入的参数个数是可以用String...args，表示多参数传入
有返回值类型的方法一定加return

在servlet里面执行的代码写在doget方法中

        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html; charset=utf-8");

防止输出出现乱码的代码表示

<%@ 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="TextServlet" method="post"> 
        <input type="text"  name="username" placeholder="请输入用户名"/><br>
        <input type="text"  name="password" placeholder="请输入密码"/><br>
        <input type="text"  name="password1" placeholder="请再次输入密码"/><br> 
        <input type="text"  name="realname" placeholder="请输入真实名字"/><br> 
        <input type="submit" value="提交"/>
        <a href="login.jsp"> 超级链接</a>
    </form>




</body>
</html>

注册的servlet类

package com.hanqi.textservlet;

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 TextServlet
 */
@WebServlet("/TextServlet")
public class TextServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public TextServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html; charset=utf-8");
        
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String password1 = request.getParameter("password1");
        String realname = request.getParameter("realname");
        
        response.getWriter().append("username:"+username+"password:"+password+"realname:"+realname);
        
        if(CheckParm(username,password,password1)){
            if(password.equals(password1)){
                Object obj=request.getServletContext().getAttribute(username);
                if(obj==null){
                    request.getServletContext().setAttribute(username, username);
                    request.getServletContext().setAttribute(password, password);
                    response.sendRedirect("message.jsp?code=1");
                }else{
                    response.sendRedirect("message.jsp?code=4");
                }
            }else{
                response.sendRedirect("message.jsp?code=3");
            }
        }else{
            response.sendRedirect("message.jsp?code=2");
        }
        
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }
    public boolean CheckParm(String...args){
        for(String s:args){
            if("".equals(s)||s==null){
                return false;
            }
        }
        
        return true;
        
    }
    

}

<%@ 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="LoginServlet" method="post"> 
        <input type="text"  name="username" placeholder="请输入用户名"/><br>
        <input type="text"  name="password" placeholder="请输入密码"/><br>
        <input type="submit" value="登陆"/>
    </form>
    
</body>
</html>

登陆的servlet类

package com.hanqi.textservlet;

import java.io.IOException;

import javax.servlet.ServletContext;
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 LoginServlet
 */
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public LoginServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html; charset=utf-8");
        
        
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        
        ServletContext application=request.getServletContext();
        Object obj=application.getAttribute(username);
        Object ob=application.getAttribute(password);
        if(obj!=null){
            String user=(String)obj;
            if(username.equals(user)){
                if(password.equals(ob)){
                    response.sendRedirect("index.jsp");
                }else{response.sendRedirect("message.jsp?code=7");}
            }else{
                response.sendRedirect("message.jsp?code=5");
                }
            }else{
                response.sendRedirect("message.jsp?code=6");
                }
        }
    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

未按要求输入的提示页面的实现

<%@ 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>
    <%
        String code=request.getParameter("code");
        if("1".equals(code)){
            out.print("<h1>注册成功！</h1>");        
        }if("2".equals(code)){
            out.print("<h1>信息输入不完整！</h1>");        
        }if("3".equals(code)){
            out.print("<h1>输入的密码不一致！</h1>");        
        }if("4".equals(code)){
            out.print("<h1>用户已经存在！</h1>");        
        }if("5".equals(code)){
            out.print("<h1>用户名错误！</h1>");        
        }if("6".equals(code)){
            out.print("<h1>用户不存在！</h1>");        
        }if("7".equals(code)){
            out.print("<h1>密码错误！</h1>");        
        }
    
    %>
</body>
</html>

servlet实现登陆注册

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