JDBCUtils

package com.mozq.jdbc;

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

/**
 *  JDBCUtils获取连接和释放资源的工具类
 * 
 * @author jie
 *
 */
public class JDBCUtils_V1 {
	/**
	 * 获取连接
	 * 
	 * @throws ClassNotFoundException
	 */
	public static Connection getConnection() {
		// 1.准备配置信息
		String dirverClass = "com.mysql.jdbc.Driver";
		String url = "jdbc:mysql://localhost:3306/jdbc_day1";
		String user = "root";
		String password = "root";
		// 2.加载驱动，获得链接
		Connection connection = null;
		try {
			Class.forName(dirverClass);
			connection = DriverManager.getConnection(url, user, password);
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return connection;
	}
	
	/**
	 * 释放资源，注意资源的释放顺序
	 */
	public static void release(Connection conn, PreparedStatement pstmt, ResultSet rs) {
		if(rs != null) {
			try {
				rs.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		if(pstmt != null) {
			try {
				pstmt.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		if(conn != null) {
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
}

　　

package com.mozq.jdbc;

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

/**
 * 	使用Properties类，从配置文件获取配置信息。实现JDBCUtils工具类
 * 
 * @author jie
 *
 */
public class JDBCUtils_V2 {
	// 1.准备配置信息
	public static String dirverClass;
	public static String url;
	public static String user;
	public static String password;
	
	static {
		ClassLoader classLoader = JDBCUtils_V2.class.getClassLoader();
		InputStream inStream = classLoader.getResourceAsStream("db.properties");
		Properties properties = new Properties();
		try {
			properties.load(inStream);
			dirverClass = properties.getProperty("dirverClass");
			url = properties.getProperty("url");
			user = properties.getProperty("user");
			password = properties.getProperty("password");
			
			Class.forName(dirverClass);
		} catch (IOException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
	}
	/**
	 * 获取连接
	 * 
	 * @throws ClassNotFoundException
	 */
	public static Connection getConnection() {
		// 2.加载驱动，获得链接
		Connection connection = null;
		try {
			connection = DriverManager.getConnection(url, user, password);
		}catch (SQLException e) {
			e.printStackTrace();
		}
		return connection;
	}
	
	/**
	 * 释放资源，注意资源的释放顺序
	 */
	public static void release(Connection conn, PreparedStatement pstmt, ResultSet rs) {
		if(rs != null) {
			try {
				rs.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		if(pstmt != null) {
			try {
				pstmt.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		if(conn != null) {
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
}

　　

package com.mozq.jdbc;

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

/**
 *  使用ResourceBundle类，从配置文件获取配置信息。实现JDBCUtils工具类
 * 
 * @author jie
 *
 */
public class JDBCUtils_V3 {
	// 1.准备配置信息
	public static String dirverClass;
	public static String url;
	public static String user;
	public static String password;

	static {
		ResourceBundle bundle = ResourceBundle.getBundle("db");
		try {
			dirverClass = bundle.getString("dirverClass");
			url = bundle.getString("url");
			user = bundle.getString("user");
			password = bundle.getString("password");

			Class.forName(dirverClass);
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
	}

	/**
	 * 获取连接
	 * 
	 * @throws ClassNotFoundException
	 */
	public static Connection getConnection() {
		// 2.加载驱动，获得链接
		Connection connection = null;
		try {
			connection = DriverManager.getConnection(url, user, password);
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return connection;
	}

	/**
	 * 释放资源，注意资源的释放顺序
	 */
	public static void release(Connection conn, PreparedStatement pstmt, ResultSet rs) {
		if (rs != null) {
			try {
				rs.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		if (pstmt != null) {
			try {
				pstmt.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		if (conn != null) {
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
}

　　

#配置文件，位于classpath：db.properties
dirverClass=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/jdbc_day1
user=root
password=root

　　

package com.mozq.jdbc.test;

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

import org.junit.Test;

import com.mozq.jdbc.JDBCUtils_V2;

public class JDBCUtils_V2Test {
	/**
	 * 测试try catch finally 代码执行顺序
	 */
	@Test
	public void tryCatchFinally() {
		System.out.println(1);
		try {
			System.out.println(2);
			//int i = 1 / 0;
			System.out.println(3);
		} catch (Exception e) {
			System.out.println(4);
		} finally {
			System.out.println(5);
		}
		System.out.println(6);
	}
	
	/**
	 * 	插入
	 */
	@Test
	public void insert() {
		//准备参数
		String user = "刘备";
		String password = "123";
		Connection conn = null;
		PreparedStatement pstmt = null;
		try {
			//获取链接
			conn = JDBCUtils_V2.getConnection();
			//获取语句执行对象
			String sql = "insert into t_user (name, password) values(?, ?)";
			pstmt = conn.prepareStatement(sql );
			pstmt.setString(1, user);
			pstmt.setString(2, password);
			//结果处理
			int row = pstmt.executeUpdate();
			if(row > 0) {
				System.out.println("插入用户成功");
			}else {
				System.out.println("插入用户失败");
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}finally {
			JDBCUtils_V2.release(conn, pstmt, null);
		}
	}
	
	/**
	 * 	查找
	 */
	@Test
	public void find() {
		//准备参数
		String user = "刘备";
		String password = "123";
		
		Connection conn = null;
		PreparedStatement pstmt = null;
		ResultSet rs = null;
		try {
			//获取链接
			conn = JDBCUtils_V2.getConnection();
			//获取语句执行对象
			String sql = "select * from t_user where name=? and password=?";
			pstmt = conn.prepareStatement(sql);
			pstmt.setString(1, user);
			pstmt.setString(2, password);
			//结果处理
			rs = pstmt.executeQuery();
			if(rs.next()) {
				System.out.println("返回用户对象");
			}else {
				System.out.println("用户或密码错误");
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}finally {
			JDBCUtils_V2.release(conn, pstmt, null);
		}
	}
	
	/**
	 * 	修改
	 */
	@Test
	public void modify() {
		//准备参数
		String user = "京东";
		
		Connection conn = null;
		PreparedStatement pstmt = null;
		try {
			//获取链接
			conn = JDBCUtils_V2.getConnection();
			//获取语句执行对象
			String sql = "update t_user set name=? where id=?";
			pstmt = conn.prepareStatement(sql);
			pstmt.setString(1, user);
			//pstmt.setInt(2, 1);
			pstmt.setString(2, "hehe");
			//结果处理
			int row = pstmt.executeUpdate();
			if(row > 0) {
				System.out.println("修改成功");
			}else {
				System.out.println("修改失败");
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}finally {
			JDBCUtils_V2.release(conn, pstmt, null);
		}
	}
	/**
	 * 	修改
	 */
	@Test
	public void delete() {
		//准备参数
		int id = 1;
		
		Connection conn = null;
		PreparedStatement pstmt = null;
		try {
			//获取链接
			conn = JDBCUtils_V2.getConnection();
			//获取语句执行对象
			String sql = "delete from t_user where id=?";
			pstmt = conn.prepareStatement(sql);
			pstmt.setInt(1, id);
			//结果处理
			int row = pstmt.executeUpdate();
			if(row > 0) {
				System.out.println("删除成功");
			}else {
				System.out.println("删除失败");
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}finally {
			JDBCUtils_V2.release(conn, pstmt, null);
		}
	}
}