JDBC工具类Utils

配置类jdbc.properties

driverName=com.mysql.cj.jdbc.Driverurl=jdbc:mysql://localhost:3306/test?serverTimezone=Asia/Shanghaiusername=rootpassword=123456

注意：test是我的数据库名

package com.chinasoft.client;import java.io.InputStream;import java.sql.*;import java.util.Properties;public class JdbcUtils {    private static String driverName=null;    private static String url=null;    private static String username=null;    private static String password=null;    static{ try{//JdbcUtils.class.getClassLoader()获取类加载器//JdbcUtils.class.getClassLoader().getResourceAsStream获取该类下的资源//     注意jdbc.properties一定要是在src目录下     InputStream in = JdbcUtils.class.getClassLoader().getResourceAsStream("jdbc.properties");     Properties properties=new Properties();     properties.load(in);//现在整个jdbc.properties里面的数据都被读取出来了，存放在properties里面了     driverName = properties.getProperty("driverName");     url = properties.getProperty("url");     username = properties.getProperty("username");     password = properties.getProperty("password");//     1.驱动只需加载一次     Class.forName(driverName); } catch (Exception e) {     e.printStackTrace(); }    }//    获取连接    public static Connection getConnection() throws SQLException { return DriverManager.getConnection(url,username,password);    }//    释放连接    public static void release(Connection conn, Statement st, ResultSet rs){ if (rs!=null){     try {  rs.close();     } catch (SQLException e) {  e.printStackTrace();     } } if (st!=null){     try {  st.close();     } catch (SQLException e) {  e.printStackTrace();     } } if (conn!=null){     try {  conn.close();     } catch (SQLException e) {  e.printStackTrace();     } }    }}

编写测试类

package com.chinasoft.client;import java.sql.Connection;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;public class JdbcUtilsTest {    public static void main(String[] args){ Connection connection = null; Statement statement=null; String sql; ResultSet resultSet=null; try {     connection = JdbcUtils.getConnection();//获取数据库连接     statement = connection.createStatement();//获取SQL的执行对象     sql="select * from user";     resultSet = statement.executeQuery(sql);//获取查询结果集 } catch (SQLException e) {     e.printStackTrace(); }finally {     JdbcUtils.release(connection,statement,resultSet); }    }}