设计模式之责任链（Chain of Responsibility）模式
Java Web中的Filter（包括struts2中的过滤器）就是典型的责任链模式，看了以下的代码，就大概能知道Filter是怎么个实现的了：
public class Request {
String requestStr;
public String getRequestStr() {
return requestStr;
}
public void setRequestStr(String requestStr) {
this.requestStr = requestStr;
}
}
public class Response {
String responseStr;
public String getResponseStr() {
return responseStr;
}
public void setResponseStr(String responseStr) {
this.responseStr = responseStr;
}
}
public interface Filter {
void doFilter(Request request, Response response, FilterChain chain);
}
public class FilterChain implements Filter {
List<Filter> filters = new ArrayList<Filter>();
int index = 0;
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);
}
}
public class HTMLFilter implements Filter {
@Override
public void doFilter(Request request, Response response, FilterChain chain) {
//process the html tag <>
request.requestStr = request.requestStr.replace('<', '[')
.replace('>', ']') + "---HTMLFilter()";
chain.doFilter(request, response, chain);
response.responseStr += "---HTMLFilter()";
}
}
public class SesitiveFilter implements Filter {
@Override
public void doFilter(Request request, Response response, FilterChain chain) {
request.requestStr = request.requestStr.replace("被就业", "就业")
.replace("敏感", "") + "---SesitiveFilter()";
chain.doFilter(request, response, chain);
response.responseStr += "---SesitiveFilter()";
}
}
public class Main {
/**
* @param args
*/
public static void main(String[] args) {
String msg = "大家好:)，<script>，敏感，被就业，网络授课没感觉，因为看不见大家伙儿";
Request request = new Request();
request.setRequestStr(msg);
Response response = new Response();
response.setResponseStr("response");
FilterChain fc = new FilterChain();
fc.addFilter(new HTMLFilter())
.addFilter(new SesitiveFilter())
;
fc.doFilter(request, response, fc);
System.out.println(request.getRequestStr());
System.out.println(response.getResponseStr());
}
}
