有同学说看不懂责任链模式，那么我用100行代码手写拦截器，让你搞懂！！！！
请问：简书怎么可以把代码格式调整？我贴出来换格式了。你们直接去Github下载工程！
public class Request {
public Request() {
}
}
public class Response {
public Response() {
super();
}
}
public class Connection {
}
拦截器接口设计
public interface Interceptor {
Responseintercept(Chain chain)throws IOException;//拦截器拦截方法，都有
interface Chain {//链
Requestrequest();
//这个方法比较重要，把它回调回去了，重复执行了proceed方法
Responseproceed(Request request)throws IOException;
@Nullable
Connectionconnection();
}
}
最重要的类：
public class RealInterceptorChainimplements Interceptor.Chain {
private final Listinterceptors;
public int index;
private final Requestrequest;
private int calls;
public RealInterceptorChain(List interceptors, int index,
Request request) {
this.interceptors = interceptors;
this.index = index;
this.request = request;
}
@Override
public Requestrequest() {
return request;
}
//从这里出发
@Override
public Responseproceed(Request request)throws IOException {
if (index >=interceptors.size())
throw new AssertionError();
calls++;
RealInterceptorChain next =new RealInterceptorChain(interceptors, index +1, request);
Interceptor interceptor =interceptors.get(index);
Response response = interceptor.intercept(next);//调用拦截器的intercepter方法,分别到不同拦截器
//得到最后一个拦截器的response。
if (index +1
throw new IllegalStateException("network interceptor "
+ interceptor +" must call proceed() exactly once");
}
return response;//又跳到了CacheInterceptor的响应处理
}
@Override
@Nullable
public Connectionconnection() {
return new Connection();
}
}
重试拦截器：
public class RetryAndFollowUpInterceptorimplements Interceptor{
@Override
public Responseintercept(Chain chain)throws IOException {
RealInterceptorChain chain2 = (RealInterceptorChain) chain;
System.out.println("我是拦截器一 RetryAndFollowUpInterceptor" + chain2.index);
Request request = chain.request();
Response response = chain.proceed(request); // 调用实现进入拦截器二，到了这里不会往下执行，而是执行下一个拦截器
System.out.println("拦截器一 RetryAndFollowUpInterceptor 响应返回");
return response;
}
}
桥接拦截器：
public class BridgeInterceptorimplements Interceptor {
@Override
public Responseintercept(Chain chain)throws IOException {
System.out.println("我是拦截器2 BridgeInterceptor");
Request request = chain.request();
Response response = chain.proceed(request);//这里会分出去
System.out.println("拦截器2响应返回 BridgeInterceptor");
return response;
}
}
缓存拦截器
public class CacheInterceptorimplements Interceptor {
@Override
public Responseintercept(Chain chain)throws IOException {
System.out.println("我是拦截器3 CacheInterceptor");
Request request = chain.request();
Response response = chain.proceed(request);
System.out.println("拦截器3响应返回 CacheInterceptor");////这里会分出去
return response;
}
}
服务器请求拦截器。最特殊，
public class ConnectInterceptorimplements Interceptor {
@Override
public Responseintercept(Chain chain)throws IOException {
System.out.println("我是最后一个拦截器 ：在这里不进行向下传递，进行消耗 ConnectInterceptor");
return new Response();//最后一个得到相应
}
}
1.为什么请求是依次的？
上一个的request引用，传递到了下一个request
public Responseproceed(Request request)throws IOException {
2.为什么后面的response先执行？
因为责任链模式
2021-06-16 23:19:34.498 25691-25691/com.glide.myapplication.myapplication I/System.out: 我是拦截器一 RetryAndFollowUpInterceptor1
2021-06-16 23:19:34.498 25691-25691/com.glide.myapplication.myapplication I/System.out: 我是拦截器2 BridgeInterceptor
2021-06-16 23:19:34.498 25691-25691/com.glide.myapplication.myapplication I/System.out: 我是拦截器3 CacheInterceptor
2021-06-16 23:19:34.498 25691-25691/com.glide.myapplication.myapplication I/System.out: 我是最后一个拦截器 ：在这里不进行向下传递，进行消耗 ConnectInterceptor
2021-06-16 23:19:34.498 25691-25691/com.glide.myapplication.myapplication I/System.out: 拦截器3响应返回 CacheInterceptor
2021-06-16 23:19:34.498 25691-25691/com.glide.myapplication.myapplication I/System.out: 拦截器2响应返回 BridgeInterceptor
2021-06-16 23:19:34.498 25691-25691/com.glide.myapplication.myapplication I/System.out: 拦截器一 RetryAndFollowUpInterceptor 响应返回
