从注入方法上看，IOC可以分为三种类型：构造函数注入，set方法属性注入，接口方法注入，spring中支持前两种注入方式。

/**  * 导演  * Created by qiqi on 2018/11/20 9:53  */ public class DirectorService {
      //剧本1     public void direct1() {
          //安排刘德华出演革离         GeLi geLi = new LiuDeHua();         //构造函数将革离注入到墨攻剧本         MoAttackService moAttackService = new MoAttackService(geLi);         //城门守卫询问         moAttackService.cityGateAsk();     }     //剧本2     public void direct2() {
          //安排刘德华出演革离         GeLi geLi = new LiuDeHua();         //set方法注入         MoAttackService moAttackService = new MoAttackService();         moAttackService.setGeLi(geLi);         //城门守卫询问         moAttackService.cityGateAsk();     }     //剧本3     public void direct3() {
          //安排刘德华出演革离         GeLi geLi = new LiuDeHua();         //接口方法注入         MoAttackService moAttackService = new MoAttackService();         moAttackService.injectGeLi(geLi);         //城门守卫询问         moAttackService.cityGateAsk();     } }

/**  * 墨攻剧本  * Created by qiqi on 2018/11/20 9:42  */ public class MoAttackService implements Acctor {
      private GeLi geLi;     //构造函数注入     public MoAttackService(GeLi geLi) {
          this.geLi = geLi;     }     public MoAttackService() {
      }     //set方法注入     public void setGeLi(GeLi geLi) {
          this.geLi = geLi;     }     //城门守卫询问     public void cityGateAsk() {
          geLi.responseAsk("I am MoAttack Geli");     } 　　//重写接口方法     @Override     public void injectGeLi(GeLi geLi) {
          geLi.responseAsk("I am MoAttack Geli");     } }

/**  *接口方法  * Created by qiqi on 2018/11/20 10:16  */ public interface Acctor {
      void injectGeLi(GeLi geLi); }

/**  * 革离  * Created by qiqi on 2018/11/20 9:45  */ public class GeLi {
      private String name;     //回答     public String responseAsk(String name) {
          return this.name = name;     } }

/**  * Created by qiqi on 2018/11/20 9:55  */ public class LiuDeHua extends GeLi {
  }

由于接口注入需要额外声明一个接口，增加了类的数目，其本质与效果与set方法注入并无区别，所以不建议接口注入