在src文件夹下创建配置文件 db.properties

 

db.properties

drivername=com.mysql.jdbc.Driverurl=jdbc:mysql://localhost:3306/mydbuser=rootpassword=root

　　

JDBCUtil.java

package com.gordon.jdbcutil;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;public class JDBCUtil {	public static String DRIVERNAME = null;	public static String URL = null;	public static String USER = null;	public static String PASSWORD = null;	public static Connection conn = null;	static {		try {			Properties props = new Properties();			//Reader in = new FileReader("db.properties");			InputStream in = JDBCUtil.class.getClassLoader().getResourceAsStream("db.properties");			props.load(in);			DRIVERNAME = props.getProperty("drivername");			URL = props.getProperty("url");			USER = props.getProperty("user");			PASSWORD = props.getProperty("password");		} catch (Exception e) {			throw new RuntimeException(e);		}	}	public static Connection getConnection() throws Exception {		if (conn != null) {			return conn;		}				Class.forName(DRIVERNAME);		conn = DriverManager.getConnection(URL, USER, PASSWORD);		return conn;	}	public static void closeResource(Connection conn, PreparedStatement st) throws SQLException {		st.close();		conn.close();	}	public static void closeResource(Connection conn, ResultSet rs, PreparedStatement st) throws SQLException {		st.close();		rs.close();		conn.close();	}}

　　* 注意其中的获取配置文件的代码。

 

jdbc01.java测试文件

package com.gordon.jdbc;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import com.gordon.jdbcutil.JDBCUtil;public class jdbc01 {		public static void main(String[] args) {		selectFunction();	}	public static void selectFunction() {		try {			//1.获取连接			Connection conn = JDBCUtil.getConnection();			// 3.sql语句			String sql = "SELECT * FROM user";			// 3.获取SQL执行者			PreparedStatement st = conn.prepareStatement(sql);			// 4.设置参数			// 5.执行sql语句			ResultSet rs = st.executeQuery();			// 6.处理数据			while (rs.next()) {				System.out.println(rs.getString("id") + ":" + rs.getString("name"));			}			// 7.释放资源			JDBCUtil.closeResource(conn, rs, st);					} catch (SQLException ex) {			System.out.println(ex.getMessage());		} catch (Exception e) {			System.out.println(e.getMessage());		}	}}