责任链模式
Chain of Responsibility Pattern
javax.servlet.Filter
在论坛中发表文章
后台要经过信息处理才可以发表或者进入数据库
传统过滤
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| public class RespoMain {
public static void main(String[] args) {
Msg msg = new Msg();
msg.setMsg("大家好，:)，欢迎访问www.baidu.com");
msg.setMsg(msg.getMsg().replace(":)","嘻嘻"));
msg.setMsg(msg.getMsg().replace("www.baidu.com"," https://www.baidu.com"));
System.out.println(msg.getMsg());
}
}
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增加Filter接口，实现doFilter方法，实现FaceFilter和HttpFilter
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| public interface Filter {
void doFilter(Msg msg);
}
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| public class FaceFilter implements Filter {
@Override
public void doFilter(Msg msg) {
msg.setMsg(msg.getMsg().replace(":)", "嘻嘻"));
}
}
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| public class HttpFilter implements Filter{
@Override
public void doFilter(Msg msg) {
msg.setMsg(msg.getMsg().replace("www.baidu.com"," https://www.baidu.com"));
}
}
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| public class RespoMain {
public static void main(String[] args) {
Msg msg = new Msg();
msg.setMsg("大家好，:)，欢迎访问www.baidu.com");
FaceFilter faceFilter = new FaceFilter();
HttpFilter httpFilter = new HttpFilter();
faceFilter.doFilter(msg);
httpFilter.doFilter(msg);
System.out.println(msg.getMsg());
}
}
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多个filter过滤，可以用数组
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| public class RespoMain {
public static void main(String[] args) {
Msg msg = new Msg();
msg.setMsg("大家好，:)，欢迎访问www.baidu.com");
List<Filter> filters = new ArrayList<>();
filters.add(new FaceFilter());
filters.add(new HttpFilter());
for (Filter filter :
filters) {
filter.doFilter(msg);
}
System.out.println(msg.getMsg());
}
}
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增加filterChain，实现Filter可实现责任链链接责任链
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| public class FilterChain implements Filter {
private List<Filter> filters = new ArrayList<>();
@Override
public void doFilter(Msg msg) {
for (Filter filter :
filters) {
filter.doFilter(msg);
}
}
FilterChain add(Filter filter) {
filters.add(filter);
return this;
}
FilterChain remove(Filter filter) {
filters.remove(filter);
return this;
}
}
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| public class RespoMain {
public static void main(String[] args) {
Msg msg = new Msg();
msg.setMsg("大家好，:)，欢迎访问www.baidu.com");
FilterChain filterChain = new FilterChain();
filterChain.add(new FaceFilter()).add(new HttpFilter());
filterChain.doFilter(msg);
System.out.println(msg.getMsg());
}
}
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责任链中断，Filter的doFilter方法返回boolean
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| public interface Filter {
boolean doFilter(Msg msg);
}
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| public class FaceFilter implements Filter {
@Override
public boolean doFilter(Msg msg) {
msg.setMsg(msg.getMsg().replace(":)", "嘻嘻"));
return false;
}
}
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| public class HttpFilter implements Filter {
@Override
public boolean doFilter(Msg msg) {
msg.setMsg(msg.getMsg().replace("www.baidu.com", " https://www.baidu.com"));
return true;
}
}
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| public class FilterChain implements Filter {
private List<Filter> filters = new ArrayList<>();
@Override
public boolean doFilter(Msg msg) {
for (Filter filter :
filters) {
if (!filter.doFilter(msg)) {
return false;
}
}
return false;
}
FilterChain add(Filter filter) {
filters.add(filter);
return this;
}
FilterChain remove(Filter filter) {
filters.remove(filter);
return this;
}
}
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| public class RespoMain {
public static void main(String[] args) {
Msg msg = new Msg();
msg.setMsg("大家好，:)，欢迎访问www.baidu.com");
FilterChain filterChain = new FilterChain();
filterChain.add(new FaceFilter()).add(new HttpFilter());
filterChain.doFilter(msg);
System.out.println(msg.getMsg());
}
}
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| 大家好，嘻嘻，欢迎访问www.baidu.com
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实现Filter
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| public class Request {
private String info;
public String getInfo() {
return info;
}
public void setInfo(String info) {
this.info = info;
}
}
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| public class Response {
private String info;
public String getInfo() {
return info;
}
public void setInfo(String info) {
this.info = info;
}
}
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| public interface Filter {
void doFilter(Request request, Response response, FilterChain filterChain);
}
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| public class OneFilter implements Filter {
@Override
public void doFilter(Request request, Response response, FilterChain filterChain) {
request.setInfo(request.getInfo() + " one filter");
filterChain.doFilter(request, response);
response.setInfo(response.getInfo() + " one filter");
}
}
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| public class TwoFilter implements Filter {
@Override
public void doFilter(Request request, Response response, FilterChain filterChain) {
request.setInfo(request.getInfo() + " two filter");
filterChain.doFilter(request, response);
response.setInfo(response.getInfo() + " two filter");
}
}
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| public class FilterChain {
private List<Filter> filters = new ArrayList<>();
private Integer index = 0;
void add(Filter filter) {
filters.add(filter);
}
void remove(Filter filter) {
filters.remove(filter);
}
public void doFilter(Request request, Response response) {
if (index == filters.size()) {
return;
}
Filter filter = filters.get(index);
index++;
filter.doFilter(request, response, this);
}
}
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| public class FilterMain {
public static void main(String[] args) {
FilterChain filterChain = new FilterChain();
filterChain.add(new OneFilter());
filterChain.add(new TwoFilter());
Request request = new Request();
request.setInfo("init request");
Response response = new Response();
response.setInfo("init response");
filterChain.doFilter(request, response);
System.out.println(request.getInfo());
System.out.println(response.getInfo());
}
}
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| init request one filter two filter
init response two filter one filter
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