What Is DI?

当一个类需要依赖另一个对象，把另一个对象实例化之后注入给这个对象的过程我们称之为DI

# Create an object dependency in traditional programming
public class Store {private Item item;public Store() {item = new ItemImpl1();    }
}# Using DI
public class Store {private Item item;public Store(Item item) {this.item = item;}
}

参考：
Intro to Inversion of Control and Dependency Injection with Spring