知识大全责任链

Posted 2022-07-18 知

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责任链模式（Chain of Responsibility）的目标是使多个对象都有机会处理请求从而避免请求的发送者和接收者之间的耦合关系将这些对象连成一条链并沿着这条链传递请求直到有一个对象处理它为止在处理用户的请求时可能要根据不同的情况对请求添加不同的处理逻辑在这时候就可以利用责任链进行设计当需要添加一个处理逻辑时可以很方便的添加一个处理的节点现在我们的需求是处理用户的请求将用户提交的字符串信息进行层层处理同时在处理完成之后返回结果时也要对返回的字符串进行层层处理而处理返回的情况时其处理的顺序和先前是正好相反的顺序首先建立用户的请求和接收对象Request和Response

package lcq filter; public class Request String requestStr; public String getRequestStr() return requestStr; public void setRequestStr(String requestStr) this requestStr = requestStr;

package lcq filter; public class Response String responseStr; public String getResponseStr() return responseStr; public void setResponseStr(String responseStr) this responseStr = responseStr;

　　我们将处理用户信息的逻辑抽象成为一个个的过滤器进一步抽象出过滤器接口Filter

package lcq filter; public interface Filter public void doFilter(Request request Response response FilterChain chain);

　　注意在Filte接口中doFilter方法参数中有FilterChain的一个变量我们再建立FilterChain类

package lcq filter; import java util ArrayList; import java util List; public class FilterChain implements Filter List<Filter> filters = new ArrayList<Filter>(); int index = ; public FilterChain addFilter(Filter f) this filters add(f); return this; @Override public void doFilter(Request request Response response FilterChain chain) if (index == filters size()) return; Filter f = filters get(index); index++; f doFilter(request response chain);

　　在FilterChain中继承了Filter接口从而实现了doFilter方法在FilterChain中又有一个index变量该变量是用来标记当前访问的是哪一个过滤器这些过滤器是存放在ArrayList中的这样用户在使用的时候就可以实现自己的过滤器编写自己的处理逻辑从而将自己的过滤器添加到ArrayList中再调用FilterChain的doFilter方法遍历整个责任链

　　下面我们编写三个过滤器

　　HTMLFilter类

package lcq filter; /** * 过滤HTML中的脚本元素 * @author lcq * */ public class HTMLFilter implements Filter @Override public void doFilter(Request request Response response FilterChain chain) request requestStr = request getRequestStr() replace( < [ ) replace( > ] HTMLFilter ); chain doFilter(request response chain); response responseStr += HTMLFilter ;

　　SesitiveFilter类

package lcq filter; public class SesitiveFilter implements Filter @Override public void doFilter(Request request Response response FilterChain chain) request requestStr = request getRequestStr() replace( 敏感 ) replace( 猫猫 haha SesitiveFilter ); chain doFilter(request response chain); response responseStr += SesitiveFilter ;

　　FaceFilter类

package lcq filter; public class FaceFilter implements Filter @Override public void doFilter(Request request Response response FilterChain chain) request requestStr = request getRequestStr() replace( :) ^V^ FaceFilter ); chain doFilter(request response chain); response responseStr += FaceFilter ;

　　最后编写测试类

package lcq filter; public class Main public static void main(String[] args) String message = 敏感词汇重庆 <script> 躲猫猫 :) ; Request request = new Request(); request setRequestStr(message); Response response = new Response(); response setResponseStr( response ); FilterChain fc = new FilterChain(); fc addFilter(new HTMLFilter()) addFilter(new SesitiveFilter()); FilterChain fc = new FilterChain(); fc addFilter(new FaceFilter()); fc addFilter(fc ); fc doFilter(request response fc); System out println( request = + request getRequestStr()); System out println( response = + response getResponseStr());

　　在上面的实例中应该注意两个地方

　　我们建立的FilterChain中继承了Filter接口所以在测试类中就可以像使用其他的过滤器一样使用FilterChain 大大提高了灵活性

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知识大全 责任链

知识大全责任链