JavaWeb个人博客项目:手把手教你实现博客后台系统之登录与注册模块4

后台系统的所有界面图以及之前的准备工作欢迎看我之前的博文>3<

具体的代码未来将传到csdn下载或github下载~

有任何问题欢迎下方评论=W=

一、图片效果

①项目目录图1与图2

②登录模块图

③注册模块图


二、设置字符集过滤器

①Java Resources的src-->建立package,命名为filter-->创建一个DoFilter的java文件,具体代码如下

(PS.这个过滤器我也是仿照csdn一个老哥的做的,在此感谢这位老哥>3<)

DoFilter.java文件:

package filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class DoFilter implements Filter {

		public DoFilter(){
			System.out.println("过滤器构造");
		}
		public void destroy() {
			System.out.println("过滤器销毁");
		}
		public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {
			request.setCharacterEncoding("utf-8"); //将编码改为utf-8
			response.setContentType("text/html;charset=utf-8");
			chain.doFilter(request, response);
		}
	 
		public void init(FilterConfig arg0) throws ServletException {
			System.out.println("过滤器初始化");
		}
	 
	}

②在WebContent-->WEB-INF-->web.xml中,设置如下内容

web.xml文件:

<?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_3_0.xsd" version="3.0">
  <display-name>MyBlog</display-name>
  <filter>
    <filter-name>Dofilter</filter-name>
    <filter-class>filter.DoFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>Dofilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
  <!-- 欢迎页,即进入项目的第一个界面 -->
  <welcome-file-list>
    <welcome-file>login.jsp</welcome-file>
  </welcome-file-list>
</web-app>

三、EL与JSTL表达式

①先载入JSTL的Jar包,在项目右键BuildPath-->Configure Build Path的Libraries里-->Add Jars-->选择目标Jar包

②为确保载入Jar包成功,应该在WebContent-->WEB-INF-->lib的文件夹中查看是否有如下内容,这次用的便是有jstl前缀的jar包

③在WebContent-->新建一个jsp文件,取名为base.jsp-->写入如下内容

(关于layui、bootstrap等框架资源百度即可,按照目录结构放入其中)

base.jsp文件:

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<c:set var="ctx" value="${pageContext.request.contextPath}"></c:set>
<link rel="stylesheet" href="${ctx }/js/layui/css/layui.css">
<script src="${ctx }/js/jquery-3.2.1.min.js"></script>
<script src="${ctx }/js/layui/layui.js"></script>
<script src="${ctx}/js/bootstrap/js/bootstrap.min.js"></script>

四、登录模块

①逻辑分析(以下为我画的管理员登录业务流程图)

 

②详细的数据库之前的博文已经写了,为了更好阅读这里再写一次

建数据库,命名为blog-->建表,命名为dai_adm,设计表的字段如下

属性名

类型

长度

允许空

是否主键

说明

adm_id

tinyint

4

NOT NULL

主键

管理员id、自增

adm_name

varchar

20

NOT NULL

 

管理员名称

adm_password

varchar

20

NOT NULL

 

管理员密码

③既然是登录,自然要与数据库进行对接,这里我使用的是mysql数据库,要求要加载好mysql的jar包,步骤同之前JSTL的Jar包设置步骤

  3.1 在Java Resources的src下-->新建package,命名为util-->新建一个config.properties文件,内容如下

(由于我mysql是接入3306端口,数据库连接时使用的用户名是root,没有设置密码,所以这么设置,如果你有密码,pwd=你的密码)

config.properties文件:

driverClass=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/blog?useUnicode=true&characterEncoding=utf-8&useSSL=false
#mysql username
user=root
#mysql password
pwd=

  3.2 在Java Resources的src下-->util包中-->新建一个class文件,命名为DBUtil,代码如下

DBUtil.java文件:

package util;


import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

public class DBUtil {
	private static String driverClass;
	private static String url;
	private static String user;
	private static String pwd;
	
	//static block静态块
	static{
		//产生properties类的实例
		Properties prop = new Properties();
		//转换成文件流
		InputStream is = DBUtil.class.getClassLoader().getResourceAsStream("util/config.properties");
		
		try {
			prop.load(is);
			driverClass = prop.getProperty("driverClass").trim();
			url = prop.getProperty("url").trim();
			user = prop.getProperty("user").trim();
			pwd = prop.getProperty("pwd").trim();
			Class.forName(driverClass);
			
			//当前类的位置
			System.out.println(DBUtil.class.getResource(""));
			//当前类的根目录的位置
			System.out.println(DBUtil.class.getClassLoader().getResource(""));
		} catch (Exception e) {
			e.printStackTrace();
		}		
	}
	
	public static Connection getConnection(){
		// 数据库的连接
		Connection conn = null;
		try {
			conn = DriverManager.getConnection(url, user,pwd);
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return conn;
	}
	public static void closeConnection(Connection conn) throws SQLException {
		conn.close();
	}
	
}

④这个项目使用了MVC结构,登录模块也就是对管理员进行操作,这里先写pojo层,再写dao层

  4.1 在src中-->新建一个package,命名为pojo-->新建一个class文件,命名为Adm,内容如下

Adm.java文件:

package pojo;

public class Adm{
	private Integer adm_id;
	private String adm_name;
	private String adm_password;
	
	public Integer getAdm_id() {
		return adm_id;
	}
	public void setAdm_id(Integer adm_id) {
		this.adm_id = adm_id;
	}
	public String getAdm_name() {
		return adm_name;
	}
	public void setAdm_name(String adm_name) {
		this.adm_name = adm_name;
	}
	public String getAdm_passward() {
		return adm_password;
	}
	public void setAdm_passward(String adm_password) {
		this.adm_password = adm_password;
	}
}

   4.2 由于后来要做分页功能,所以还要封装一个类-->pojo包中-->新建一个class,命名为ChangePage,内容如下

ChangePage.java文件:

package pojo;

public class ChangePage {
	private int page; //默认第一页
	private int limit; //默认一页10条数据
	private int startRow = (page-1)*limit;//mysql里语句随之发生改变
	private String sort;//排序字段
	private String order;//排序关键字
	public int getPage() {
		return page;
	}
	public void setPage(int page) {
		this.page = page;
	}
	public int getLimit() {
		return limit;
	}
	public void setLimit(int limit) {
		this.limit = limit;
	}
	public int getStartRow() {
		return (page-1)*limit;
	}
	public void setStartRow(int startRow) {
		this.startRow = startRow;
	}
	public String getSort() {
		return sort;
	}
	public void setSort(String sort) {
		this.sort = sort;
	}
	public String getOrder() {
		return order;
	}
	public void setOrder(String order) {
		this.order = order;
	}
}

 4.3 在src中-->新建一个package,命名为dao-->新建一个interface文件,命名为AdmDao,内容如下

AdmDao.java文件:

package dao;

import java.util.ArrayList;

import pojo.Adm;

public interface AdmDao {
	//1.查询管理员,返回一个管理员类型  这是login里头的方法
	public Adm getAdm(String username,String password);
	//2查询所有的管理员
	public ArrayList<Adm> getAllAdm();
	//3.添加管理员
	public boolean insertAdm(String username,String pwd);
	//4.根据id删除管理员
	public boolean deleteAdm(int id);
	//5.修改管理员信息
	public boolean updateAdm(Adm a);
	//6.根据adm_name查询是否存在该用户,即id唯一,用户名唯一
	public boolean queryIsExist(String username);
	//7.根据id,查询一个管理员
	public Adm getOneAdm(int adm_id);
	//8 分页查询所有的管理员
	public ArrayList<Adm> getPageAdm(int page,int limit);
	
}

4.4 写AdmDao的实现类,本应该放在不同的包里,我当时为了简便,依然放在了dao包

dao包-->新建class文件,命名为AdmDaoImpl-->实现AdmDao接口,代码如下

AdmDaoImpl.java文件:

package dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import pojo.Adm;
import pojo.ChangePage;
import util.DBUtil;

public class AdmDaoImpl implements AdmDao {

	// 分页方法
	@Override
	public ArrayList<Adm> getPageAdm(int page, int limit) {
		ArrayList<Adm> adm = new ArrayList<Adm>();
		Connection conn = DBUtil.getConnection();
		ChangePage cp = new ChangePage();
		cp.setLimit(limit);
		cp.setPage(page);
		int startRow = cp.getStartRow();
		String sql = "select * from dai_adm limit " + startRow + "," + limit + "";
		// 预编译
		try {
			PreparedStatement prep = conn.prepareStatement(sql);
			ResultSet rst = prep.executeQuery();
			while (rst.next()) {
				Adm ad = new Adm();
				ad.setAdm_id(rst.getInt(1));
				ad.setAdm_name(rst.getString("adm_name"));
				ad.setAdm_passward(rst.getString("adm_password"));
				adm.add(ad);
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			try {
				DBUtil.closeConnection(conn);
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		return adm;
	}

	// 查询所有的管理员
	@Override
	public ArrayList<Adm> getAllAdm() {
		ArrayList<Adm> adm = new ArrayList<Adm>();
		Connection conn = DBUtil.getConnection();
		// 在数据库中添加记录
		String sql = "select * from dai_adm";
		// 预编译
		try {
			PreparedStatement prep = conn.prepareStatement(sql);
			ResultSet rst = prep.executeQuery();
			while (rst.next()) {
				Adm ad = new Adm();
				ad.setAdm_id(rst.getInt(1));
				ad.setAdm_name(rst.getString("adm_name"));
				ad.setAdm_passward(rst.getString("adm_password"));
				adm.add(ad);
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			try {
				DBUtil.closeConnection(conn);
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		return adm;
	}

	@Override
	public Adm getAdm(String username, String password) {
		Adm a = null;
		Connection conn = DBUtil.getConnection();
		String sql = "select * from dai_adm where adm_name = ? and adm_password = ?";
		// 预编译
		PreparedStatement prep;
		try {
			prep = conn.prepareStatement(sql);
			prep.setString(1, username);
			prep.setString(2, password);
			ResultSet rst = prep.executeQuery();
			if (rst.next()) {
				System.out.println("啊啊啊,我是servlet,我已经查到信息了!!!");
				a = new Adm();
				a.setAdm_id(rst.getInt("adm_id"));
				a.setAdm_name(rst.getString("adm_name"));
				a.setAdm_passward(rst.getString("adm_password"));
				return a;
			} else {
				// System.out.println(username+","+password);
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				DBUtil.closeConnection(conn);
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		return a;
	}

	// 3.添加管理员
	@Override
	public boolean insertAdm(String username, String pwd) {
		Connection conn = DBUtil.getConnection();
		// 在数据库中添加记录
		String sql = "insert into dai_adm(adm_name,adm_password) values(?,?)";
		// 预编译
		PreparedStatement prep;
		try {
			prep = conn.prepareStatement(sql);
			prep.setString(1, username);
			prep.setString(2, pwd);
			prep.executeUpdate();
			return true;
		} catch (SQLException e) {
			e.printStackTrace();
			return false;
		} finally {
			try {
				DBUtil.closeConnection(conn);
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}

	@Override
	public boolean deleteAdm(int adm_id) {
		Connection conn = DBUtil.getConnection();
		// 在数据库中删除记录
		String sql = "delete from dai_adm where adm_id = ?";
		// 预编译
		PreparedStatement prep;
		try {
			prep = conn.prepareStatement(sql);
			prep.setInt(1, adm_id);
			prep.executeUpdate();
			return true;
		} catch (SQLException e) {
			e.printStackTrace();
			return false;
		} finally {
			try {
				DBUtil.closeConnection(conn);
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}

	@Override
	public boolean updateAdm(Adm a) {
		Connection conn = DBUtil.getConnection();
		// 在数据库中修改记录
		String sql = "update dai_adm set adm_name = ?,adm_password = ? where adm_id=?";
		// 预编译
		PreparedStatement prep;
		try {
			prep = conn.prepareStatement(sql);
			prep.setString(1, a.getAdm_name());
			prep.setString(2, a.getAdm_passward());
			prep.setInt(3, a.getAdm_id());
			prep.executeUpdate();
			return true;
		} catch (SQLException e) {
			e.printStackTrace();
			return false;
		} finally {
			try {
				DBUtil.closeConnection(conn);
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}

	@Override
	public boolean queryIsExist(String username) {
		Connection conn = DBUtil.getConnection();
		// 在数据库中查询记录
		String sql = "select * from dai_adm where adm_name = ?";
		// 预编译
		PreparedStatement prep;
		try {
			prep = conn.prepareStatement(sql);
			prep.setString(1, username);
			ResultSet rst = prep.executeQuery();
			if (rst.next()) {
				return true;
			} else {
				return false;
			}

		} catch (SQLException e) {
			e.printStackTrace();

		} finally {
			try {
				DBUtil.closeConnection(conn);
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		return false;
	}

	@Override
	public Adm getOneAdm(int adm_id) {
		Adm a = null;
		Connection conn = DBUtil.getConnection();
		// 在数据库中修改记录
		String sql = "select * from dai_adm where adm_id = ?";
		// 预编译
		PreparedStatement prep;
		try {
			prep = conn.prepareStatement(sql);
			prep.setInt(1, adm_id);
			ResultSet rst = prep.executeQuery();
			a = new Adm();
			if (rst.next()) {
				a.setAdm_id(rst.getInt(1));
				a.setAdm_name(rst.getString("adm_name"));
				a.setAdm_passward(rst.getString("adm_password"));
				return a;
			}

		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				DBUtil.closeConnection(conn);
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		return a;
	}

}

      PS:这里有一个方法叫做getAllAdm(),还有一个方法叫做getPageAdm()。

      前者我是用来获得总共有多少条管理员信息,后者我是用来获得分页信息与分页数据的,前者本来不需要在数据库上走那么多步骤。

      因为ResultSet创建的对象可以使用last()方法跳到最后一条数据,然后再使用getRow()方法获得总数,这里建议大家按照这种方法。

⑤Service层:src-->新建package包,命名为servlet-->新建一个Servlet文件,命名为LoginServlet-->在URL mappings中改名为/login-->键入代码,如下

LoginServlet.java文件:

package 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;

import dao.AdmDao;
import dao.AdmDaoImpl;
import pojo.Adm;

/**
 * Servlet implementation class LoginServlet
   WebServlet里的/login就是刚刚改的URL Mappings的内容
 */
@WebServlet("/login")
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)
	 * void getSession()方法相当于得到一个session对象,而void setAttribute()和String Attribute分别是对属性赋值和得到属性值的方法。
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//response.getWriter().append("Served at: ").append(request.getContextPath());
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		
		PrintWriter out = response.getWriter();
		String name = request.getParameter("username");
		String pwd = request.getParameter("pwd");
		
		AdmDao a = new AdmDaoImpl();
		Adm adm = a.getAdm(name	, pwd);
		System.out.println(a.toString());
		if(adm!=null) {
			request.getSession().setAttribute("admin",adm);			
			//重定向到成功页面
			response.sendRedirect("index.jsp"); 
		}else {
			//out.println("啊啊啊,我应该转发到失败的界面了");
			request.setAttribute("errMsg", "账号或密码错误,请重新输入信息!");
			//转发到login界面
			request.getRequestDispatcher("login.jsp").forward(request, response); 
			return;
		}
		
	}

	/**
	 * @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);
	}

}

⑥WebContent-->新建jsp文件,命名为login.jsp-->键入代码,如下(使用了bootstrap和layui框架)

login.jsp文件:

<%@ 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">
<link rel="stylesheet" href="./js/bootstrap/css/bootstrap.min.css">
<link rel="stylesheet" href="./css/b_register.css">
<%@include file="base.jsp"%>
<title>登录</title>
</head>
<body>
	<%
		String errorMsg = (String) request.getAttribute("errMsg");
		if (errorMsg == null) {
			errorMsg = "";
		}
	%>
	<div id="box">
		<!--  action="${ctx}/login" -->
		<form id="myform" method="post" action="${ctx}/login">
			<div class="form-group">
				<label for="username">用户名</label> <input type="text"
					class="form-control" id="username" name="username"
					placeholder="请输入用户名:"> <span id="tip"
					style="color: red; margin-top: 20px;"><%=errorMsg%></span>

			</div>

			<div class="form-group">
				<label for="pwd">密码</label> <input type="password"
					class="form-control" id="pwd" name="pwd" placeholder="请输入密码:">
			</div>

			<button type="submit" class="btn btn-default btn_" id="btn">确定</button>
			<span style="margin-left: 250px;"></span> <a href="register.jsp"><button
					type="button" class="btn btn-default btn_">注册</button></a>
		</form>
	</div>
	<script type="text/javascript">
		layui.use([ 'layer' ], function() {
			layui.use([ 'form' ], function() {
				var form = layui.form;
			});
			//	点击提交执行的内容
			$('#username').blur(function() {
				//或者取长度
				if ($("#username").val() == "") {
					layer.msg("用户名不能输入为空哦!", {
						icon : 2
					});
					return;
				}
			});
			//点击提交,表单验证
			$('#btn').click(function() {
				if ($("#pwd").val() === "") {
					layer.msg("密码不能输入为空哦!", {
						icon : 2
					});
					return;
				}
			});
		});
	</script>
</body>
</html>

5.1 这里CSS目录如下(CSS并不重要,可以自己调整)

5.2 b_register的css样式如下

b_register.css文件:

@CHARSET "UTF-8";
*{
	margin:0;
	padding:0;
}
body{
    background:url("./image/19.jpg") no-repeat;
}
#box{
	width:520px;
	height:400px;
	margin:200px auto;
	border-radius:20px;
	background-color: rgba(0, 0, 0, 0.3);
	box-shadow:1px 2px 5px black;
	padding: 1px;
	position:relative;
	background-image: url(./image/18.gif); 
    opacity: 0.8;
}
#myform{
	margin:30px;
}
span{
	margin-left:100px;
}
.btn_{
	color:tomato;
	margin-top:30px;
}

5.3 base的css样式如下

base.css文件:

@charset "UTF-8";
body {
	width: 100%;
	height: 100%;
	background: url('../css/image/18.gif');
	overflow: hidden;
}

 #box {
	height:550px;
	display:flex;
	align-items:center;
	justify-content:center;
	align-content:center;  
	
}

⑤当输入用户名或密码错误时,应该有的提示

⑥当输入密码正确时,应进入后台主界面,这里大家在WebContent里新建一个jsp文件,取名为index即可,这里放一张后台图,具体的下篇博文再更


五、注册模块 

①逻辑分析(以下为我画的管理员注册业务流程图,注册成功即自动跳转登录页面)

②Service层:这里主要就是首先判断你是否输入用户名,用户名输入过后判断是否这个用户名已经存在(用户名和id都是唯一的),然后再验证你两次密码是否相同,最后再进入注册。

所以说前台可以判断1是是否输入2是密码两次是否一致

后台连接数据库后应该是进行了两个操作1是判断用户名是否存在2是进行往数据库里增加数据

2.1 src-->在servlet包里-->新建一个Servlet文件,命名为RegisterServlet-->在URL mappings中改名为/register-->键入代码,如下

RegisterServlet.java文件:

package 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;

import dao.AdmDao;
import dao.AdmDaoImpl;

/**
 * Servlet implementation class RegisterServlet
   WebServlet里的/register就是刚刚改的URL Mappings的内容
 */
@WebServlet("/register")
public class RegisterServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public RegisterServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String result = "false";
		PrintWriter writer = null;
		try {
			PrintWriter out = response.getWriter();
			//1.接收参数
			String username = request.getParameter("username");
			String pwd = request.getParameter("pwd");
			AdmDao a = new AdmDaoImpl();
			boolean flag= a.insertAdm(username,pwd);
		    if(flag){
		    	result = "true";
			}
		    writer =  response.getWriter();
		    writer.write(result);
		}catch(Exception e) {
			e.printStackTrace();
		}finally {
			writer.flush();
			writer.close();
		}
		
		
	}

	/**
	 * @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);
	}

}

2.2 src-->在servlet包里-->新建一个Servlet文件,命名为QueryAdmIsExist-->在URL mappings中改名为/isExist-->键入代码,如下

QueryAdmIsExist.java文件:

package 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;

import dao.AdmDao;
import dao.AdmDaoImpl;

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

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse resp) throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		resp.setCharacterEncoding("utf-8");
		resp.setContentType("text/html;charset=utf-8");
		//根据姓名查询用户是否存在 改的更完善了一点
		String result = "false";
		PrintWriter writer = null;
		try {
			String username = request.getParameter("username");
			AdmDao a = new AdmDaoImpl();
			boolean flag = a.queryIsExist(username);
			if(flag==true) {
				result = "true";
			}
			writer =  resp.getWriter();
			writer.write(result);
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			writer.flush();
			writer.close();
		}
		
	}

	/**
	 * @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);
	}

}

③在WebContent下-->新建jsp文件,命名为register.jsp-->键入代码,如下(这里使用的是ajax,和上面登录模块不一样,注意区别)

register.jsp文件:

<%@ 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">
<link rel="stylesheet" href="./js/bootstrap/css/bootstrap.min.css">
<link rel="stylesheet" href="./css/b_register.css">
<%@include file="base.jsp"%>
<title>注册</title>
</head>
<body>
<div id="box">
<form id="myform"  method="post">
  <div class="form-group">
    <label for="username">用户名</label>
    <input type="text" class="form-control" id="username" name="username" placeholder="请输入用户名:">
    <span id="tip" style="color:red;margin-top:20px;"></span>
  </div>
  
  <div class="form-group">
    <label for="pwd">密码</label>
    <input type="password" class="form-control" id="pwd" name="pwd" placeholder="请输入密码:">
  </div>
   <div class="form-group">
    <label for="conFirmPwd">确认密码</label>
    <input type="password" class="form-control" id="conFirmPwd" name="conFirmPwd" placeholder="请再次输入密码:">
  </div>
  <button type="button" class="btn btn-default btn_" id = "btn">提交</button>
  <span style="margin-left:250px;"></span>
  <a href="login.jsp"><button type="button" class="btn btn-default btn_">返回</button></a>
</form>
</div>
</body>
<script>
layui.use([ 'layer' ], function() {
	/* alert(0); */
	layui.use([ 'form' ], function() {
		var form = layui.form;
	});
	var isOk = false;
	//	点击提交执行的内容
	$('#username').blur(function() {
		//或者取长度
		if ($("#username").val() == "") {
			layer.msg("不能输入为空哦!", {
				icon : 2
			});
			return;
		}else {
				$.post('isExist', 
				{
					username : $('#username').val()
				},
				function(result) { 
					//alert(typeof result);
					if(result=="true"){
						//alert(1);
						isOk = false;
						//利用jquery对元素设置样式
						$('#username').css("border", "1px solid red");
						//html() 设置标签之间的 内容
						$('#tip').html('该用户已存在');
						$('#tip').css("color", "red");
						return;
					}else{
						//alert(2);
						isOk = true;
						//利用jquery对元素设置样式
						$('#username').css("border", "1px solid gray");
						//html() 设置标签之间的 内容
						$('#tip').html('该用户名可用');
						$('#tip').css("color", "green");
					}
					
			}, "text");
		}
	});
	//点击提交,表单验证
	$('#btn').click(function() {
		if (!isOk) {
			return;
		}	
	  if($("#pwd").val() !== $("#conFirmPwd").val()){
			layer.msg("两次密码输入不同!",{
				icon : 2
			});
			return;
		}
		 //提交表单
   	   $.post("register",//后台地址
			{
				username: $("#username").val(),
					 pwd:$("#pwd").val(),
			},//需要提交到后台的数据
			function(result){
				//alert(typeof result);
				//alert(result);
				if (result) {
					//添加成功
					layer.msg("注册成功", {
						icon : 1
					});
					window.location.href = "login.jsp";
				}else{
					layer.msg("注册失败",{
						icon : 2
					});
					// 这里使用JQuery实现会有问题 
					document.getElementById("myform").reset();
					$('#tip').html("");
				}
			},
			"json"); 
		//清空表单
	});
});
</script>
</html>

④注册时用户名存在或可用的区别图片如下


最后有任何问题欢迎给我留言,我看到就一定会回复的>w< 

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转载自blog.csdn.net/DaiYuMeng/article/details/104685578