Eclipse使用（七）—— 使用Eclipse创建JavaWeb项目并使用JDBC连接数据库实现简单的登陆注册功能

本项目继承于： Eclipse使用（六）—— 使用Eclipse创建JavaWeb项目

一、创建数据库表（这里使用的是Mysql5.7）

DDL语句如下：

[sql] view
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CREATE TABLE `tb_user` (  

  `u_id` int(11) NOT NULL AUTO_INCREMENT COMMENT '用户编号',  

  `u_username` varchar(30) NOT NULL COMMENT '用户名',  

  `u_password` varchar(30) NOT NULL COMMENT '密码',  

  PRIMARY KEY (`u_id`)  

) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;  

二、项目需要使用的jar示例

三、编写持久层和业务层代码

项目src目录结构预览：

1、在src目录下创建com.mengfei.entity包，并在包中创建实体类User

package com.mengfei.entity;

import java.io.Serializable;

public class User implements Serializable{
private static final long serialVersionUID = 1L;

private Integer uid;
private String username;
private String password;
public Integer getUid() {
return uid;
}
public void setUid(Integer uid) {
this.uid = uid;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
@Override
public String toString() {
return "User{" +
"uid=" + uid +
", username='" + username + '\'' +
", password='" + password + '\'' +
'}';
}
}

2、在com.mengfei包中创建dao包，并在包中创建类BaseDao

package com.mengfei.dao;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class BaseDao {
protected Connection conn;
protected PreparedStatement ps;
protected ResultSet rs;

public Connection getConnection() {
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/demo?useSSL=false", "alex", "123");
//Class.forName("oracle.jdbc.driver.OracleDriver");
//conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl", "alex", "123");
/**
* com.mysql.jdbc.Driver是创建连接的驱动类，Oracle使用的是oracle.jdbc.driver.OracleDriver
* jdbc:mysql://localhost:3306/demo?useSSL=false是要连接的url地址，Oracle使用的是jdbc:oracle:thin:@localhost:1521:orcl
* localhost代表本地连接，如果使用远程连接则要改成IP地址
* demo是要连接的mysql中数据库的名字，Oracle中用的是实例orcl
* ?useSSL=false是参数，不写也能连接，Oracle中不需要
* alex是要连接的用户名
* 123是用户的密码
*/
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}

public void closeDB(ResultSet rs, PreparedStatement ps, Connection conn) {

try {
if (rs != null) {
rs.close();
}
if (ps != null) {
ps.close();
}
if (conn != null) {
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}

}

// 测试是否连接上数据库
public static void main(String[] args) {
BaseDao dao = new BaseDao();
System.out.println(dao.getConnection());
}

}

3、在com.mengfei.dao包中创建接口UserDao

package com.mengfei.dao;

import com.mengfei.entity.User;

public interface UserDao {
/**
* 用户注册
* @param user
* @return
*/
Integer register(User user);

/**
* 用户登陆
* @param user
* @return
*/
User login(User user);
}

4、在com.mengfei.dao包中创建impl包，并在包中创建类UserDaoImpl，该类继承BaseDao，实现UserDao

package com.mengfei.dao.impl;

import java.sql.SQLException;

import com.mengfei.dao.BaseDao;
import com.mengfei.dao.UserDao;
import com.mengfei.entity.User;

public class UserDaoImpl extends BaseDao implements UserDao {

@Override
public Integer register(User user) {
int row = 0;
conn = getConnection();
String sql = "insert into tb_user(u_username,u_password) values(?,?)";
try {
ps = conn.prepareStatement(sql);
ps.setString(1, user.getUsername());
ps.setString(2, user.getPassword());
row = ps.executeUpdate();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
closeDB(rs, ps, conn);
}
return row;
}

@Override
public User login(User user) {
User u=null;
conn=getConnection();
String sql="select * from tb_user where u_username=? and u_password=?";
try {
ps=conn.prepareStatement(sql);
ps.setString(1, user.getUsername());
ps.setString(2, user.getPassword());
rs = ps.executeQuery();
while(rs.next()){
u=new User();
u.setUid(rs.getInt(1));
u.setUsername(rs.getString(2));
u.setPassword(rs.getString(3));
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally {
closeDB(rs, ps, conn);
}
return u;
}

}

5、在com.mengfei包中创建biz包，并在包中创建接口UserBiz

package com.mengfei.biz;

import com.mengfei.entity.User;

public interface UserBiz {
/**
* 用户注册
* @param username
* @param password
* @return
*/
Boolean register(String username, String password);

/**
* 用户登陆
* @param username
* @param password
* @return
*/
User login(String username, String password);
}

6、在com.mengfei.biz包中创建impl包，并在包中创建类UserBizImpl实现UserBiz

package com.mengfei.biz.impl;

import com.mengfei.biz.UserBiz;
import com.mengfei.dao.UserDao;
import com.mengfei.dao.impl.UserDaoImpl;
import com.mengfei.entity.User;

public class UserBizImpl implements UserBiz {

private UserDao userDao = new UserDaoImpl();

@Override
public Boolean register(String username, String password) {
User user = new User();
user.setUsername(username);
user.setPassword(password);
Integer result = userDao.register(user);
if (result > 0) {
return true;
}
return false;
}

@Override
public User login(String username, String password) {
User user = new User();
user.setUsername(username);
user.setPassword(password);
User u = userDao.login(user);
return u;
}

}

7、在com.mengfei包中创建servlet包，并在包中创建UserServlet

package com.mengfei.servlet;

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;

import com.mengfei.biz.UserBiz;
import com.mengfei.biz.impl.UserBizImpl;
import com.mengfei.entity.User;

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

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
UserBiz userBiz=new UserBizImpl();
String username = request.getParameter("username");
String password = request.getParameter("password");
String operate = request.getParameter("operate");
if(!"".equals(username)&&!"".equals(password)&&!"".equals(operate)) {
if("register".equals(operate)) {
Boolean b = userBiz.register(username, password);
if(b) {
request.getRequestDispatcher("success.jsp").forward(request, response);
}else {
response.sendRedirect("index.jsp");
}
}else if("login".equals(operate)) {
User user = userBiz.login(username, password);
if(null!=user) {
request.setAttribute("username", user.getUsername());
request.getRequestDispatcher("success.jsp").forward(request, response);
}else {
response.sendRedirect("index.jsp");
}
}else {
response.sendRedirect("index.jsp");
}
}else {
response.sendRedirect("index.jsp");
}
}

}

四、编写表现层代码（web.xml文件暂时不用管它）

1、在WebContent目录中创建js目录，将jquery-3.2.1.js文件放进去

2、编写index.jsp（放在WebContext目录下）

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script src="js/jquery-3.2.1.js"></script>
</head>
<body>
<form id="form" action="UserServlet" method="post" onsubmit="return checkUser1()">
<input type="hidden" name="operate" id="operate">
帐号：<input type="text" name="username" id="username"><br>
密码：<input type="password" name="password" id="password"><br>
<input type="submit" value="注册">
<input id="login" type="button" value="登陆" onclick="checkUser2()">
</form>
</body>
</html>
<script>
//注册使用表单提交事件进行验证提交
function checkUser1() {
var username=$('#username').val();
var password=$('#password').val();
if(''==username){
alert('用户名不能为空！');
return false;
}
if(''==password){
alert('密码不能为空！');
return false;
}
$('#operate').val('register');
return true;
}
//登陆使用单击事件进行验证提交
function checkUser2() {
var username=$('#username').val();
var password=$('#password').val();
if(''==username){
alert('用户名不能为空！');
return false;
}
if(''==password){
alert('密码不能为空！');
return false;
}
$('#operate').val('login');
$('#form').get(0).action='UserServlet';
$('#form').get(0).submit();
}
</script>

3、在WebContent目录下创建success.jsp文件

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<c:if test="${empty username}">
注册成功！
</c:if>

<c:if test="${!empty username}">
登陆成功！欢迎 ${username} !
</c:if>
</body>
</html>

五、部署测试

1、右键点击本地server将项目添加到Tomcat中

2、启动Tomcat，在浏览器中输入localhost:8080/JDBCJavaWebDemo/index.jsp，显示如下图：

OK，到这里就可以自己进行注册和登陆测试啦