写了一个spring小程序，set报null错误，请问各位大神是为什么啊

[mixturer]

使用apacha的basicdatasource连接池，写了一个spring小程序，测试获得mySQL数据库连接，set注入数据库连接的基本参数后，提示错误

Exception in thread "main" java.sql.SQLException: Cannot create JDBC driver of class '' for connect URL 'null'
	at org.apache.commons.dbcp2.BasicDataSource.createConnectionFactory(BasicDataSource.java:2023)
	at org.apache.commons.dbcp2.BasicDataSource.createDataSource(BasicDataSource.java:1897)
	at org.apache.commons.dbcp2.BasicDataSource.getConnection(BasicDataSource.java:1413)
	at com.alex.util.MySQLDataSource.getConnection(MySQLDataSource.java:43)
	at com.alex.util.test.TestCase.main(TestCase.java:16)
Caused by: java.sql.SQLException: No suitable driver
	at java.sql.DriverManager.getDriver(Unknown Source)
	at org.apache.commons.dbcp2.BasicDataSource.createConnectionFactory(BasicDataSource.java:2007)
	... 4 more 

后多次修改调试，发现问题出在

 	public MySQLDataSource() {
		bds = new BasicDataSource();
		bds.setDriverClassName(driver);
		bds.setUrl(url);
		bds.setUsername(username);
		bds.setPassword(password);
	}

修改成

 public MySQLDataSource() {
		bds = new BasicDataSource();
	}

	@Override
	public Connection getConnection() throws SQLException{
		bds.setDriverClassName(driver);
		bds.setUrl(url);
		bds.setUsername(username);
		bds.setPassword(password);
		return bds.getConnection();
	}

提示可以获得链接，请问这是为什么啊，是注入顺序问题吗，我百度过之后，还是无解，本人小白，求指教。附所有源代码。

applicationContext.xml

 <?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context" xmlns:jdbc="http://www.springframework.org/schema/jdbc"  
	xmlns:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:jpa="http://www.springframework.org/schema/data/jpa" xmlns:util="http://www.springframework.org/schema/util"
	
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
		http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd
		http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
		http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd
		http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd
		">
		
		<bean id="mydatasource" class="com.alex.util.MySQLDataSource">
			<property name="driver" value="com.mysql.jdbc.Driver"/>
			<property name="url" value="jdbc:mysql://localhost:3306/jsd1407?useUnicode=true&characterEncoding=utf8"/>
			<property name="username" value="root"/>
			<property name="password" value="root"/>
		</bean>
</beans>

interface:

 package com.alex.util;

import java.sql.Connection;
import java.sql.SQLException;

public interface DataSource {

	public abstract Connection getConnection() throws SQLException;

	public abstract void closeConnection() throws SQLException;

}

MySQLDataSource:

 package com.alex.util;

import java.sql.Connection;
import java.sql.SQLException;

import org.apache.commons.dbcp2.BasicDataSource;

public class MySQLDataSource implements DataSource {
	
	private String driver;
	private String url;
	private String username;
	private String password;
	private BasicDataSource bds;
	
	public void setDriver(String driver) {
		this.driver = driver;
	}

	public void setUrl(String url) {
		this.url = url;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	public MySQLDataSource() {
		bds = new BasicDataSource();
	}

	@Override
	public Connection getConnection() throws SQLException{
		bds.setDriverClassName(driver);
		bds.setUrl(url);
		bds.setUsername(username);
		bds.setPassword(password);
		return bds.getConnection();
	}

	@Override
	public void closeConnection() throws SQLException{
		bds.close();
	}
}

[Inhibitory]

Caused by: java.sql.SQLException: No suitable driver 数据库的驱动jar包版本不对

[mixturer]

我这边的包是对的，我给你截图看一下，程序我还在增加功能，估计有点乱，所以你先看看截图的包能不能OK

[xzc8861153]

你的错误提示是数据库的jar包不对，你看下是不是你没导入jar包，或者jar包导错了。 不报错了记得写个测试程序看看是否真的连接上了

[mixturer]

包都有的，我测试过了，就是

bds.setDriverClassName(driver);
        bds.setUrl(url);
        bds.setUsername(username);
        bds.setPassword(password);

修改了一下位置就好了，我自己测试通过了，就是不知道为什么就好了，导包都OK的

[研发与思维]

spring加载时应该是这样的顺序，先实例化MySQLDataSource，然后spring再去设置你的那几个属性，而不是你自已去手动set那几个属性。 问题原因应该是spring实例化对象后还没有set那和个属性，你就开始调连接了。 你的getConnection里面的几个set操作是可以去掉的。

[mixturer]

楼上你好，按照你的知道我测试了一下，OK没有问题，我有个问题，如果不使用set的话，BasicDataSource没有被设置值啊，为什么可以得到数据源？