学步园

package com.cai.jdbc;
import java.sql.Connection;
import java.sql.DriverManager;
import java.util.Properties ;
public class ConnectionUtil {
/**
* 1
*在方法中固化连接参数
* @return 数据库连接
*/
public Connection getConnection(){
Connection conn = null ;
try{
Class.forName("com.mysql.jdbc.Driver") ;

conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/stud", "root", "root") ;

return conn ;

}catch(Exception e){
e.printStackTrace() ;
}
return null ;
}

/**
* 2
*通过方法参数方式传递连接参数
* @return 数据库连接
*/
public Connection getConnection(String driver, String url, String user, String password){

Connection conn = null ;

try{
Class.forName(driver) ;
conn = DriverManager.getConnection(url, user, password) ;

return conn ;

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

return null ;
}

/**
* 3
*通过properties配置文件的方式灵活配置连接参数，properties中的属性名固化
* @return 数据库连接
*/
public Connection openConnection(){

Connection conn = null ;
String driver = "" ;
String url = "" ;
String user = "" ;
String password = "" ;
Properties props = new Properties() ;
try{
props.load(this.getClass().getClassLoader().getResourceAsStream("DBConfig.properties")) ;
driver = props.getProperty("driver") ;
url = props.getProperty("url") ;
user = props.getProperty("user") ;
password = props.getProperty("password") ;

Class.forName(driver) ;
conn = DriverManager.getConnection(url, user, password) ;

return conn ;
}catch(Exception e){
e.printStackTrace() ;
}

return null ;
}

public static void main(String []args){
ConnectionUtil cu = new ConnectionUtil() ;

System.out.println("1、---->" + cu.getConnection()) ;
System.out.println("2、---->" + cu.getConnection("com.mysql.jdbc.Driver",
"jdbc:mysql://localhost:3306/stud", "root", "root")) ;
System.out.println("3、---->" + cu.openConnection()) ;

}

}