servlet实现登陆注册

时间：2022-01-23 13:19:36

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("".equals(code)){

            out.print("<h1>注册成功！</h1>");

        }if("".equals(code)){

            out.print("<h1>信息输入不完整！</h1>");

        }if("".equals(code)){

            out.print("<h1>输入的密码不一致！</h1>");

        }if("".equals(code)){

            out.print("<h1>用户已经存在！</h1>");

        }if("".equals(code)){

            out.print("<h1>用户名错误！</h1>");

        }if("".equals(code)){

            out.print("<h1>用户不存在！</h1>");

        }if("".equals(code)){

            out.print("<h1>密码错误！</h1>");

        }

    %>

</body>

</html>

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