java 获取数据库连接

/**

*ConnectionUtil .java

*

*

*/

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()) ;

}

}