java设计模式（二）：2.2责任链（组合链）

例子：简单的过滤器

程序目录结构与原理

 

1.Filter.java过滤器接口类

package filter;

public interface Filter {
	public String doFilter(String str);
}

2.Filter1.java过滤器实现类

package filter.impl;

import filter.Filter;

public class Filter1 implements Filter{

	@Override
	public String doFilter(String str) {
		str += "Filter1,";
		return str;
	}

}

3.Filter2.java过滤器实现类

package filter.impl;

import filter.Filter;

public class Filter2 implements Filter{

	@Override
	public String doFilter(String str) {
		str += "Filter2,";
		return str;
	}

}

4.Filter3.java、Filter4.java、Filter5.java与Filter1.java、Filter2.java类似

5.FilterChain.java过滤器链条类

package filter;

import java.util.ArrayList;
import java.util.List;

public class FilterChain implements Filter{
	List filters = new ArrayList();
	
	public FilterChain addFilter(Filter filter){
		filters.add(filter);
		return this;
	}
	
	public String doFilter(String str){
		for(Filter f:filters){
			str = f.doFilter(str);
		}
		return str;
	}
}

6.Main.java程序主方法

import filter.FilterChain;
import filter.impl.*;

public class Main {
	public static void main(String[] args) {
		String str = "123,mxm,456,";
		
		FilterChain fc = new FilterChain();
		fc.addFilter(new Filter1())
		  .addFilter(new Filter2());
		
		FilterChain fc2 = new FilterChain();
		fc2.addFilter(new Filter3())
		   .addFilter(new Filter4());
		
		FilterChain fcs = new FilterChain();
		fcs.addFilter(fc).addFilter(new Filter5()).addFilter(fc2);
		
		str = fcs.doFilter(str);
		System.out.println(str);
	}
}

程序打印结果：

123,mxm,456,Filter1,Filter2,Filter5,Filter3,Filter4,