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本文链接：https://blog.youkuaiyun.com/iteye_12959/article/details/81653658

本文介绍了一种基于正则表达式的过滤器执行机制，通过定义一系列的HandlerConfig配置，每个配置包含一个正则表达式，用于决定哪些过滤器需要被执行。示例中展示了如何根据传入的字符串选择性地执行不同的过滤器。

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private HandlerConfig [] handlerConfigs;    
private int firstElement = -1;   
private String doRegex;   
/**  
     * 这个方法是核心方法，它根据正则表达式来决定哪些filter需要被执行，哪些filter不需要被执行  
     */  
    public void executeHandler() {   
        if (handlerConfigs == null) {   
            // 调用业务方法   
            return;   
        }   

        ++firstElement;   
        if (firstElement < handlerConfigs.length) {   
            if (handlerConfigs[firstElement].getPattern().matcher(doRegex).matches()) {   
                handlerConfigs[firstElement].getHandler().executeHandler(this);   
            } else {   
                this.executeHandler();   
            }   
        }   
    }  

private HandlerConfig [] handlerConfigs; 
private int firstElement = -1;
private String doRegex;
/**
	 * 这个方法是核心方法，它根据正则表达式来决定哪些filter需要被执行，哪些filter不需要被执行
	 */
	public void executeHandler() {
		if (handlerConfigs == null) {
			// 调用业务方法
			return;
		}

		++firstElement;
		if (firstElement < handlerConfigs.length) {
			if (handlerConfigs[firstElement].getPattern().matcher(doRegex).matches()) {
				handlerConfigs[firstElement].getHandler().executeHandler(this);
			} else {
				this.executeHandler();
			}
		}
	}

firstElement += 1;   
for (; firstElement < handlerConfigs.length ; firstElement++) {   
  if (handlerConfigs[firstElement].getPattern().matcher(doRegex).matches()) {   
    handlerConfigs[firstElement].getHandler().executeHandler(this);   
    return;   
  }   
}



public class AuthTestHandler implements Handler {   

    public void executeHandler(HandlerChain handlerChain){   
        System.out.println("1----------check the user in this filter!");   
        handlerChain.executeHandler();   
        System.out.println("2----------check the user in this filter!");   
    }   
}  


public class AuthTestHandler implements Handler {

	public void executeHandler(HandlerChain handlerChain){
		System.out.println("1----------check the user in this filter!");
		handlerChain.executeHandler();
		System.out.println("2----------check the user in this filter!");
	}
}


public class HandlerConfig {   
    private Handler handler;   
    private String handlerName;   
    private String regex;   
private Pattern pattern;   
//省略getter和setter方法   
}



public static void main(String[] args) {   

        HandlerConfig [] configs = new HandlerConfig[]{   
            new HandlerConfig(), new HandlerConfig(), new HandlerConfig()   
        };   
        configs[0].setHandler(new AuthTestHandler());   
        configs[0].setHandlerName("authFilter");   
        configs[0].setRegex("\\d*");   


        configs[1].setHandlerName("charsetFilter");   
        configs[1].setHandler(new CharsetTestHandler());   
        configs[1].setRegex("^[A-Za-z]+$");   

        configs[2].setHandlerName("otherFilter");   
        configs[2].setHandler(new OtherTestHandler());   
        configs[2].setRegex("\\d*");   

        System.out.println("chain1");   

        EasyHandlerChain chain = new EasyHandlerChain("21");   
        chain.setHandlerConfigs(configs);   
        chain.executeHandler();   

        System.out.println("");   
        System.out.println("chain2");   


        EasyHandlerChain chain1 = new EasyHandlerChain("asdf");   
        chain1.setHandlerConfigs(configs);   
        chain1.executeHandler();   
    }