import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Collection;
import java.util.Properties;

public class JDBC {
    private Properties p = new Properties();
    private static String driver;
    private static String url;
    private static String user;
    private static String psw;

    public static void main(String[] args) throws Exception {
        new JDBC().run();
    }
    
    void run() throws Exception{
        p.load(this.getClass().getResourceAsStream("properties"));//利用反射获取calss信息
        driver    =p.getProperty("driver"); //把获取信息赋值给变量
        url    =p.getProperty("url");     //把获取信息赋值给变量

user =p.getProperty("user");//把获取信息赋值给变量
 psw =p.getProperty("pwd"); //把获取信息赋值给变量
Class.forName(driver);
 Connection c ;
 c= DriverManager.getConnection(url,user,psw); 
Statement sta = c.createStatement();
 String sql = "select ename from emp"; 
ResultSet rs=sta.executeQuery(sql);
 while(rs.next()){
 System.out.println(rs.getString(1));
 }
 } 
}

Properties//配置文件 new File

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://122.114.147.148:3306/java0613
user=java0613
pwd=java0613