JDBC series: (2.5) create JDBCUtils tool classes

1. Create the db.properties file url=jdbc:mysql://localhost:3306/testdbuser=rootpassword=rootdriverClass=com.mysql.jdbc.Driver

2. JDBC tool class: JDBCUtil.javapackage com.rk.db.utils;import java.io.IOException;import java.io.InputStream;import java.util.Properties;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;/** * JDBC tool class * @ author RK * * / public class JDBCUtil {private static final String url; private static final String user; private static final String password Private static final String driverClass / * static code block (loaded only once) * / static {try {/ / read the db.properties file InputStream inStream = JDBCUtil.class.getClassLoader () .getResourceAsStream ("db.properties") Properties props = new Properties (); / / load file props.load (inStream); / / read information url = props.getProperty ("url") User = props.getProperty ("user"); password = props.getProperty ("password"); driverClass = props.getProperty ("driverClass"); / / register driver Class.forName (driverClass) } catch (IOException e) {System.out.println ("error reading database configuration file"); throw new RuntimeException (e) } catch (ClassNotFoundException e) {System.out.println ("database driver registration error"); throw new RuntimeException (e) }} / * get the database connection * @ return database connection * / public static Connection getConnection () {try {return DriverManager.getConnection (url,user,password) } catch (SQLException e) {System.out.println ("error getting database connection"); throw new RuntimeException (e) }} / * close Connection, Statement, and ResultSet * @ param conn database connections * @ param stmt commands for executing SQL statements * @ param rs result sets * / public static void close (Connection conn,Statement stmt ResultSet rs) {closeQuietly (rs) CloseQuietly (stmt); closeQuietly (conn) } / * quietly shut down database resources * @ param ac implements the object of the AutoCloseable interface * / public static void closeQuietly (AutoCloseable ac) {if (ac! = null) {try {ac.close () } catch (Exception e) {e.printStackTrace ();}}