spring复杂对象的创建

• 第一步 创建一个类 实现 beanFactory 接口 ，实现三个方法

public  class MyConfigFactoryBean implements FactoryBean<Connection> {

    @Override
    public Connection getObject() throws Exception {
        Class.forName("com.mysql.jdbc.Driver");
        Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/db1", "root", "root");
        return connection;
    }
    @Override
    public Class<?> getObjectType() {
        return Connection.class;
    }
    @Override
    public boolean isSingleton() {
        return false;
    }
}

• 在applicationContext.xml中配置bean标签

  <bean id="connection" class="cn.itcast.controller.MyConfigFactoryBean"></bean>

• 通过创建aoc容器，调用getBean返回的是一个复杂对象

 @Test
    public void test1(){
        ApplicationContext ac=new ClassPathXmlApplicationContext("applicationContext.xml");
        Connection connection =(Connection) ac.getBean("connection");
        System.out.println(connection);
    }

• 如果需要返回的是工厂本身，需要在getBean方法的参数前面加上 &

public void test1(){
        ApplicationContext ac=new ClassPathXmlApplicationContext("applicationContext.xml");
        Connection connection =(Connection) ac.getBean("connection");
        MyConfigFactoryBean factoryBean =(MyConfigFactoryBean) ac.getBean("&connection");
        System.out.println(connection);
        System.out.println(factoryBean);
    }