责任链

其实我一直都不太喜欢去死记硬背那些神马设计模式，但不得不说，你一定要对设计模式有一个大体的概念，知道什么情况下用什么设计模式就OK了。今天写了一个责任链：

 

Handler:

 

public abstract class Handler {

	protected Handler nextHandler;
	
	
	public Handler getNextHandler() {
		return nextHandler;
	}

	public abstract void invoke(Object o);
	
	
	
	public void setNextHandler(Handler nextHandler) {
		this.nextHandler = nextHandler;
	}
	
}

 

 

FilterChain(或者叫HandlerHolder):

 

 

public class FilterChain {
	
	private Handler rootHandler;
	private Handler currentHandler;
	
	
	
	public Handler getRootHandler() {
		return rootHandler;
	}

	public Handler getCurrentHandler() {
		return currentHandler;
	}
	
	public FilterChain setNextHandler(Handler nextHandler) {
		
		if(null == nextHandler || nextHandler.equals(currentHandler)) {
			return this;
		}
		
		//第一次设置
		if(null == rootHandler) {
			rootHandler = nextHandler;
			this.currentHandler = nextHandler;
			
		}else{
			//非第一次，将nextHandler设置成当前handler.nextHandler
			//然后将最新添加的handler设置为currentHandler
			if(null != currentHandler) {
				this.currentHandler.setNextHandler(nextHandler);
				this.currentHandler = nextHandler;
			}
		}
		return this;
	}
}

 

 

再写两个Handler实现类：

 

 

public class DxmHandler extends Handler{

	@Override
	public void invoke(Object t) {
		System.out.println("this is the dxm handler....");
		
		if(nextHandler != null) {
			nextHandler.invoke(0);
		}
	}
}

 

    public class DdHandler extends Handler{

	@Override
	public void invoke(Object o) {
		System.out.println("this is the dd handler....");
		
		if(nextHandler != null) {
			nextHandler.invoke(0);
		}
	}
}

 

 

 

最后测试一下：

 

  public static void main(String[] args) {

		
		
		Handler dxmHandler = new DxmHandler();
		Handler ddHandler = new DdHandler();
		
		FilterChain chain = new FilterChain();
		chain.setNextHandler(dxmHandler).setNextHandler(ddHandler).setNextHandler(ddHandler);
		chain.getRootHandler().invoke(new Object());
	}

 

Game Over.