JDBC

Posted 2020-10-09 Adi_Wood

package AdiWood.JDBC;

import java.io.FileInputStream;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

public class JDBC {

public static void main(String[] args) throws Exception{
Connection conn = null;//创建变量三步骤，1，名字；2，类型；3，赋值
Statement stmt = null;
ResultSet rs = null;
try{

Properties pps = new Properties();//0，获取文件信息
pps.load(new FileInputStream("database.properties") );

String ip = pps.getProperty("ip");
String port = pps.getProperty("port");
String dbname = pps.getProperty("dbname");
String username = pps.getProperty("username");
String password = pps.getProperty("password");
System.out.println(ip);

Class.forName("com.mysql.jdbc.Driver");//1，加载驱动（添加Driver类）

conn = DriverManager//2，连接数据库
.getConnection("jdbc:mysql://"+ip+":"+port+"/"+dbname+"?user="+username+"&password"+password);

stmt = conn.createStatement();//3，创建一个执行sql语句的工具

String sql_1 = "insert into students values(‘1‘,‘aw‘,‘27‘)";//4，编写sql语句

stmt.execute(sql_1);//5，使用这个工具执行sql语句

String sql_3 = "insert into score values(‘2‘,‘99‘)";
stmt.execute(sql_3);

String sql_2 = "select * from students";

rs = stmt.executeQuery(sql_2);//查询的特殊之处在于有返回值

while(rs.next()){
System.out.println(rs.getString(2));//字段名&索引无区别
}

}catch(Exception e){
e.printStackTrace();
}finally{

// if(conn!=null){//conn=null
// conn.close();
// }
//
//
// if(stmt!=null){
// stmt.close();
// }
//
//
// if(rs!=null){
// rs.close();
// }

closeConnection(conn,stmt,rs);


}


}

private static void closeConnection(Connection conn, Statement stmt,
ResultSet rs) throws SQLException {
// TODO Auto-generated method stub

if(conn!=null){//conn=null
conn.close();
}

if(stmt!=null){
stmt.close();
}


if(rs!=null){
rs.close();
}
}

}