JDBC-mysql，查询数据库信息

package com.oracle.jdbc.mysql;


import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
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 {


private static String driver=null;
private static String url=null;
private static String user=null;
private static String password=null;

static{
Properties p=new Properties();
try {
p.load(new FileInputStream(new File("jdbc.Properties")));

driver=p.getProperty("driver");
url=p.getProperty("url");
user=p.getProperty("user");
password=p.getProperty("password");
} catch (IOException e) {
e.printStackTrace();
System.out.println("读取配置文件失败");
}
}


public static Connection getConn(){
Connection conn=null;
try {
Class.forName(driver);
conn=DriverManager.getConnection(url, user, password);
} catch (ClassNotFoundException e) {
System.out.println("加载驱动失败");
e.printStackTrace();
} catch (SQLException e) {
System.out.println("连接数据库失败,请检查连接地址或用户名,密码");
e.printStackTrace();
}
return conn;

}


public static void main(String[] args) {
try {
String sql="select * from cls";
Connection conn=getConn();
PreparedStatement ps=conn.prepareStatement(sql);
ResultSet rs=ps.executeQuery();
while(rs.next()){
System.out.println(rs.getInt(1)+" : "+rs.getString(2));
}
} catch (SQLException e) {
System.out.println("执行sql失败");
e.printStackTrace();
}
}

}

注意：在项目里创建jdbc.Properties文件添加以下键值对：

driver=com.mysql.jdbc.Driver
url=jdbc\:mysql\://127.0.0.1\:3306/my_db
user=root
password=*******