抽取数据库连接池

古城微笑少年丶 2021-12-03 05:21 153阅读 0赞

**JDBCUtil工具类（一级）：**

package com.test;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    
    public class JDBCUtil {
        
    	{
        
    		try {
        
    			Class.forName(DRI);
    		} catch (ClassNotFoundException e) {
        
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    	}
    
    	public static final String DRI = "com.mysql.jdbc.Driver";
    	public static final String URL = "jdbc:mysql://localhost:3306/jiejie";
    	public static final String USERNAME = "root";
    	public static final String PASSWORD = "root";
    
    //	获取连接方法
    	public static Connection getCollection() throws Exception {
        
    		Connection connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
    		return connection;
    	}
    
    //	释放资源
    	public static void release(ResultSet rs, PreparedStatement ps, Connection conn) throws Exception {
        
    		if (rs != null) {
        
    			rs.close();
    			rs = null;
    			System.out.println("ResultSet已经关闭");
    		}
    		if (ps != null) {
        
    			ps.close();
    			ps = null;
    		}
    		if (conn != null) {
        
    			conn.close();
    			conn = null;
    		}
    
    	}
    
    }

**JDBCUtil工具类（升级版）：**

package com.test;
    
    import java.io.FileInputStream;
    import java.io.FileNotFoundException;
    import java.io.IOException;
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.util.Properties;
    
    public class JDBCUtil {
        
    	{
        
    		try {
        
    			// 加载 类
    			Class.forName(driver);
    		} catch (ClassNotFoundException e) {
        
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    	}
    
    	static {
        
    		Properties properties = new Properties();
    		try {
        
    //			加载properties中的数据
    			properties.load(new FileInputStream("hhh.properties"));
    			driver = properties.getProperty("driver");
    			url = properties.getProperty("url");
    			username = properties.getProperty("username");
    			password = properties.getProperty("password");
    		} catch (FileNotFoundException e) {
        
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		} catch (IOException e) {
        
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    	}
    
    	public static String driver;
    	public static String url;
    	public static String username;
    	public static String password;
    
    //	获取连接方法
    	public static Connection getCollection() throws Exception {
        
    		Connection connection = DriverManager.getConnection(url, username, password);
    		return connection;
    	}
    
    //	释放资源
    	public static void release(ResultSet rs, PreparedStatement ps, Connection conn) throws Exception {
        
    		if (rs != null) {
        
    			rs.close();
    			rs = null;
    			System.out.println("ResultSet已经关闭");
    		}
    		if (ps != null) {
        
    			ps.close();
    			ps = null;
    		}
    		if (conn != null) {
        
    			conn.close();
    			conn = null;
    		}
    
    	}
    
    }

**hhh.properties**

driver=com.mysql.jdbc.Driver
    url=jdbc:mysql://localhost:3306/jiejie
    username=root
    password=root

**测试类：**

package com.test;
    
    import java.sql.Connection;
    import java.sql.ResultSet;
    
    public class Test3 {
        
    	public static void main(String[] args) {
        
    		try {
        
    			Connection connection = JDBCUtil.getCollection();
    			ResultSet i = connection.prepareStatement("select * from u_p").executeQuery();
    			while (i.next()) {
        
    				int a = i.getInt("id");
    				String name = i.getString("username");
    				String pw = i.getString("pw");
    				System.out.println(a + "----" + name + "-----" + pw);
    			}
    			JDBCUtil.release(i, null, connection);
    		} catch (Exception e) {
        
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    	}
    }