理解java的控制反转和依赖注入

http://blog.163.com/taodengwen@126/blog/static/87199341201191383429693/

public interface Person {
    void sayHello();
}


public class Chinese implements Person {
    public void sayHello() {
           System.out.println("您好 !");
    }
}


public class American implements Person {

    public void sayHello() {
                System.out.println("How do you do .");
           }

}



//传统类里此类new Chinese/American
public class User {
    Person p;
    public Person getP() {
         return p;
    }
     //使用setter注入
    public void setP(Person p) {
       this.p = p;
    }


   //调用person子类重写的sayHello方法，这里的p并没有实例化
    public void function(){
       p.sayHello();
    }

}


//外部容器

public class Container{

    public static User getBean(){

        Person p=new Chinese();

        User user = new User();

        //由容器‘注入’实例

        user.setP(p);

        return user;

    }

}


public class Test{

    public static void main(String[] args){

           User user = Container.getBean();

           user.function();

    }

}

依赖注入的三种方式：
http://yejiansuo.iteye.com/blog/789895