MVC简单分层思想（连接数据库）

图片内容是所有的包名，文件名。

1.创建（M）模型

package oa.bean;

public class User {

    private String userName;
    private String passWord;

    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 [userName=" + userName + ", passWord=" + passWord + "]";
    }

}

2.创建DAO层

创建Dao层接口

package oa.dao;

import oa.bean.User;

/**
 * @author Administrator
 *
 */
public interface IUserDao {

    public boolean login(User user);

    public boolean insert(User entity);
}

2.创建Dao层实现类

package oa.dao;

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

import oa.Util.JDBCuntl;
import oa.bean.User;

public class UserDaoImpl implements IUserDao {

    // 封装数据库操作属性

    Connection conn = null;

    PreparedStatement pstm = null;

    ResultSet rs = null;

    // 第一步：声明返回值变量
    boolean falg = false;

    // 登录
    @Override
    public boolean login(User user) {

        // 第二步：获取连接对象
        try {
            conn = JDBCuntl.getConnection();
            // 第三步：声明sql语句
            String sql = "select * from user";

            // 第四步：根据sql语句创建预处理对象
            pstm = conn.prepareStatement(sql);

            // 第五步：执行查询
            rs = pstm.executeQuery();

            // 第六步：判断
            while (rs.next()) {
                String uname = rs.getString(1);
                String upwd = rs.getString(2);

                if (uname.equals(user.getUserName())
                        && upwd.equals(user.getPassWord())) {
                    return true;
                }
            }

        } catch (Exception e) {

            e.printStackTrace();
        } finally {
            // 第八步：释放资源
            try {
                JDBCuntl.close(rs, pstm, conn);
            } catch (SQLException e) {

                e.printStackTrace();
            }
        }

        // 判断
        /*
         * if("admin".equals(user.getUserName()) &&
         * "123456".equals(user.getPassWord())){ return true; }else{ return
         * false; }
         */

        return false;
    }

    // 注册
    @Override
    public boolean insert(User entity) {

        try {
            // 第二步：获取连接对象
            conn = JDBCuntl.getConnection();

            // 第三步：声明sql语句（插入）
            String sql = "insert into user(userName,passWord) values(?,?)";

            // 第四步：根据sql语句出创建对象
            pstm = conn.prepareStatement(sql);

            // 第五步：为占位符赋值
            int index = 1;
            pstm.setObject(index++, entity.getUserName());
            pstm.setObject(index++, entity.getPassWord());

            // 第六步：执行语句
            int i = pstm.executeUpdate();

            // 第七步：判断执行
            if (i > 0) {
                falg = true;
            }

        } catch (Exception e) {

            e.printStackTrace();
        } finally {
            try {
                JDBCuntl.close(null, pstm, conn);
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return falg;
    }

}

3.创建Service层

1.创建service层接口

package oa.service;

import oa.bean.User;

public interface IUserService {

	public boolean login(User user);

	public boolean insert(User entity);
}

2.创建service的实现类

package oa.service;

import oa.bean.User;
import oa.dao.IUserDao;
import oa.dao.UserDaoImpl;

public class UserServiceImpl implements IUserService {

	// 封装实体操作类
	private IUserDao uDao = new UserDaoImpl();

	@Override
	public boolean login(User user) {

		return uDao.login(user);
	}

	@Override
	public boolean insert(User entity) {

		return uDao.insert(entity);
	}

}

4.建立一个工具链接数据库

package oa.Util;

import java.sql.*;
import java.util.Properties;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;

/**
 * 获取数据库连接对象的工具类
 * @author Administrator
 * @version 1.0
 */
public class JDBCuntl {

    private static String driverClass = null;
    private static String url = null;
    private static String user = null;
    private static String password = null;

    //通过静态块获取jdbc.properties中的数据库驱动信息并初始化静态成员变量
    static{
        Properties props = new Properties();

        InputStream is = JDBCuntl.class.getClassLoader().getResourceAsStream("jdbc.properties");

            try {
                props.load(is);

                driverClass = props.getProperty("jdbc.driver");
                url = props.getProperty("jdbc.url");
                user = props.getProperty("jdbc.user");
                password = props.getProperty("jdbc.password");
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

            /*driverClass="com.mysql.jdbc.Driver";
            url="jdbc:mysql://localhost:3306/user";
            user="root";
            password="1";*/

    }

    /**
     * 根据获取的数据库驱动信息来创建数据库连接对象并返回
     * @return 连接对象
     * @throws Exception
     */
    public static Connection getConnection() throws Exception{
        Connection conn = null;

        Class.forName(driverClass);

        conn = DriverManager.getConnection(url, user, password);

        return conn;

    }

    /**
     * 统一关闭JDBC资源的方法
     * @param rs 结果集对象
     * @param stmt 语句对象
     * @param conn 连接对象
     * @throws SQLException
     */
    public static void close(ResultSet rs,Statement stmt,Connection conn) throws SQLException{
        if(rs != null){
            rs.close();
            rs = null;
        }

        if(stmt != null){
            stmt.close();
            stmt = null;
        }

        if(conn != null){
            conn.close();
            conn = null;
        }
    }

}

其中的文件是方便读取数据库，也方便更改数据库
文件内容是：

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/user
jdbc.user=root
jdbc.password=1

如果连接数据库有问题，可以测试数据库
测试代码：

package oa.Util;

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

public class TestUtil {

    /**
     * @param args
     */
    public static void main(String[] args) {

        try {
            Connection conn=JDBCuntl.getConnection();
            PreparedStatement psmt=conn.prepareStatement("select * from user");
            ResultSet rs=psmt.executeQuery();

            while (rs.next()) {

                System.out.println(rs.getString(1)+"\t"+rs.getString(2));
            }
            JDBCuntl.close(rs, psmt, conn);
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

}

5.创建Servlet（控制器 C）

package oa.servlet;

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

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

public class LoginSuccess extends HttpServlet {

	/**
	 * Constructor of the object.
	 */
	public LoginSuccess() {
		super();
	}

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	/**
	 * The doGet method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to get.
	 *
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doPost(request, response);
	}

	/**
	 * The doPost method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to post.
	 *
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html;charset=utf-8");
		PrintWriter out = response.getWriter();

		out.println("登录成功！欢迎你：" + request.getParameter("user"));

		out.flush();
		out.close();
	}

	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException if an error occurs
	 */
	public void init() throws ServletException {
		// Put your code here
	}

}

6.创建登录页面，注册页面

<!DOCTYPE html>
<html>
<head>
<title>Login.html</title>

<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="this is my page">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">

<!--<link rel="stylesheet" type="text/css" href="./styles.css">-->

<script type="text/javascript">
	function register() {

		window.location = "register.html";

	}
</script>

</head>

<body>
	<h1>欢迎使用XXXX点餐系统</h1>
	<form action="LoginServlet" method="post">
		用户名：<input type="text" name="user"><br> <br> 密码：<input
			type="password" name="pwd"><br> <br> <input
			type="submit" value="提交">     <input
			type="button" value="注册" onclick="register()">     <input
			type="reset" value="重置">
	</form>
</body>
</html>

7.创建一些跳转页面（成功，失败页面）

成功页面   此处用servlet实现

response.setContentType("text/html;charset=utf-8");
		PrintWriter out = response.getWriter();

		out.println("登录成功！欢迎你：" + request.getParameter("user"));

		out.flush();
		out.close();

失败页面    

response.setContentType("text/html;charset=utf-8");
		PrintWriter out = response.getWriter();

		out.print("登录失败！用户名或者密码错误！");

		out.flush();
		out.close();

8.创建注册页面和注册成功失败页面

package oa.servlet;

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

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

import oa.bean.User;
import oa.service.IUserService;
import oa.service.UserServiceImpl;

public class RegisterService extends HttpServlet {

	/**
	 * Constructor of the object.
	 */
	public RegisterService() {
		super();
	}

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	/**
	 * The doGet method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to get.
	 *
	 * @param request
	 *            the request send by the client to the server
	 * @param response
	 *            the response send by the server to the client
	 * @throws ServletException
	 *             if an error occurred
	 * @throws IOException
	 *             if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doPost(request, response);
	}

	/**
	 * The doPost method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to
	 * post.
	 *
	 * @param request
	 *            the request send by the client to the server
	 * @param response
	 *            the response send by the server to the client
	 * @throws ServletException
	 *             if an error occurred
	 * @throws IOException
	 *             if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html;charset=utf-8");
		PrintWriter out = response.getWriter();

		// 获取用户输入的数据
		String userName = request.getParameter("user");
		String passWord = request.getParameter("pwd");

		request.setCharacterEncoding("UTF-8");

		// 创建实体类
		User entity = new User();

		// 为实体对象赋值
		entity.setUserName(userName);
		entity.setPassWord(passWord);

		// 调用Service层实现用户登录业务
		IUserService uService = new UserServiceImpl();

		boolean falg = uService.insert(entity);

		if (falg==true) {
			response.sendRedirect("rSuccess.html");
		}else{
			response.sendRedirect("rFail.html");
		}

		out.flush();
		out.close();
	}

	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException
	 *             if an error occurs
	 */
	public void init() throws ServletException {
		// Put your code here
	}

}

注册页面

<!DOCTYPE html>
<html>
  <head>
    <title>register.html</title>

    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">

    <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->

  </head>

  <body>
    <form action="RegisterService" method="post">
    用户姓名：<input type="text" name="user"><br/><br/>

    密码：<input type="password" name="pwd"><br/><br/>
     <input type="submit" name="提交" value="提交"><br/>

    </form>
  </body>
</html>

成功页面

<!DOCTYPE html>
<html>
  <head>
    <title>rSuccess.html</title>

    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">

    <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->

  </head>

  <body>
   	<font color="red" size="6">注册成功</font>
  </body>
</html>

失败页面

<!DOCTYPE html>
<html>
  <head>
    <title>rFail.html</title>

    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">

    <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->

  </head>

  <body>
   	<font color="red" size="6">注册失败</font>
  </body>
</html>

此处一定要在webRoot下的

　　　　　　　　WEB—INF下的

　　　　　　　　　　　　lib文件内将数据库jar包导入《一定要导入jar包》