Java设计模式（三）

talk is cheap show me the code

享元模式

• 享元模式

interface FlyWeight{
      void doA(String name);
}

//享元模式即为保证对象创建过多找出内存溢出等问题，实现一个可分享共用对象
class FlyWeightObj implements FlyWeight{
      void doA(String name){
            system.out.println("this is Fobj")
      }
}

//共享数据
class FlyWeightFactory{
   public static ConcurrentHashMap<String, FlyWeight> allFlyWeight = new ConcurrentHashMap<String, FlyWeight>();
   
    public static FlyWeight getFlyWeight(Stirng name){
          if(null == allFlyWeight.get(name)){
                synchronized(allFlyWeight ){
                      if(null == allFlyWeight.get(name)){
                      FlyWeight f = new FlyWeightObj ();
                      allFlyWeight .add(name,f);
                       }
                  }
              return allFlyWeight .get(name);
          }
    }
}

责任链模式

• 责任链模式Filter

interface Filter{
      void  doFilter(Request req,Response rep,ChainFilter cf);
}

class FilterA implements Filter{
      void  doFilter(Request req,Response rep,ChainFilter cf){
                //do AnyTHING
                 cf.doFilter(req,rep,cf);
        }
}

class FilterB implements Filter{
      void  doFilter(Request req,Response rep,ChainFilter cf){
                //do AnyTHING
                 cf.doFilter(req,rep,cf);
        }
}

//将Filter 加入链
class ChainFilter inplements Filter{

      //责任链
      List<Filter> filters = new ArrayList<>();
      //filter引用顺序
      private int index = 0;      

      public ChainFilter addFilter(Filter f ){
            filters.add(f);
            return this;
      }

      public void doFilter(Request req,Response rep,ChainFilter cf){
              if(index = filters.size())
                      return;
              Filter f = filters.get(index);
              index++;
              f.doFilter(req,rep,cf);
      }
}


//测试类
class Test{
      public static void main(String[] args){
            Filter fa = new FilterA();
            Filter fb = new FilterB();

            ChainFilter chain = new ChainFilter();
            chain.addFilter(fa);
            chain.addFilter(fa);

            chain.doFilter(new Fequest(),new Response,chain);
      }
}

命令模式

• 命令模式 遥控

//命令接口
interface Command{
    void doCommand();
}
//电视接口
class Tv{
      public void doOn(){

      }


      public void doOff(){
   
      }

      public void doChange(){

      }
}
//按钮
class ChangeTv   implements  Command{
      private Tv tv ;

      pulic ChangeTv   (Tv tv){
            this.tv = tv;
      }
      void doCommand(){
            tv.doChange();
      }
}
//按钮
class OffTv   implements  Command{
      private Tv tv ;

      pulic Offtv(Tv tv){
            this.tv = tv;
      }
      void doCommand(){
            tv.doOff();
      }
}
//按钮
class OnTv   implements  Command{
      private Tv tv ;

      pulic Ontv(Tv tv){
            this.tv = tv;
      }
      void doCommand(){
            tv.doOn();
      }
}
//遥控
class Controller{
      private  ChangeTv ctv, OnTv   otv,OffTv   offtv;
      
      public Controller( ChangeTv ctv, OnTv  otv,OffTv   offtv){
              this.ctv = ctv;
              this.otv = otv;
              this.offtv = offtv;
      }
     public void doOn(){
            otv.doCommand();
      }


      public void doOff(){
             offtv.doCommand();
      }

      public void doChange(){
            ctv.doCommand();
      }
}

//测试
class Test{
        public static void main(String[] args){
              Tv tv = new Tv();
              .......
              Controller ct = new Controller(ctv, otv, offtv)
               ct.doChange();
               ct.doOff();
        }
}