Android Okhttp3的使用与运行流程

基本使用

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fun okhttp3Demo() {         val client: OkHttpClient = OkHttpClient.Builder().build()//创建OkHttpClient         val r: Request = Request.Builder().url("").build()//创建Request请求         val call:okhttp3.Call = client.newCall(r)//创建一个Call         //添加回调并且添加到等待缓存         call.enqueue(object : okhttp3.Callback {             override fun onFailure(call: okhttp3.Call, e: IOException) {               }               override fun onResponse(call: okhttp3.Call, response: okhttp3.Response) {               }         })         //call.execute()//直接加入运行缓存     }

 

运行过程图

 

 

 

Call接口的实现类RealCall 

　　HttpClient调用newCall(r:Request)方法 创建Call的实现类RealCall

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@Override public Call newCall(Request request) {   return RealCall.newRealCall(this, request, false /* for web socket */); }

　　跳转到RealCall的newRealCall方法

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static RealCall newRealCall(OkHttpClient client, Request originalRequest, boolean forWebSocket) {     // Safely publish the Call instance to the EventListener.     RealCall call = new RealCall(client, originalRequest, forWebSocket);     call.eventListener = client.eventListenerFactory().create(call);     return call;   }

　　找到RealCall的enqueue()方法

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@Override public void enqueue(Callback responseCallback) {     synchronized (this) {         if (executed) throw new IllegalStateException("Already Executed");         executed = true;     }     captureCallStackTrace();     eventListener.callStart(this);     //调用了HttpClient的Dispatcher的enqueue方法  此时创建了一个Runable的实现类 AsyncCall     client.dispatcher().enqueue(new RealCall.AsyncCall(responseCallback)); }

　　先看AsyncCall  实现了NamedRunnable接口  NamedRunnable实现了Runnable  其run方法调用了AsyncCall的execute()方法

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public abstract class NamedRunnable implements Runnable {   protected final String name;     public NamedRunnable(String format, Object... args) {     this.name = Util.format(format, args);   }     @Override public final void run() {     String oldName = Thread.currentThread().getName();     Thread.currentThread().setName(name);     try {       execute();     } finally {       Thread.currentThread().setName(oldName);     }   }     protected abstract void execute(); }

　　进入AsyncCall方法的execute()

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@Override protected void execute() {         try{             //...other             //添加interceptors拦截器  责任链             Response response = getResponseWithInterceptorChain();             //...other         } finally {             client.dispatcher().finished(this);         }     }       Response getResponseWithInterceptorChain() throws IOException {         // Build a full stack of interceptors.         List<Interceptor> interceptors = new ArrayList<>();         interceptors.addAll(client.interceptors());         interceptors.add(retryAndFollowUpInterceptor);         interceptors.add(new BridgeInterceptor(client.cookieJar()));         interceptors.add(new CacheInterceptor(client.internalCache()));         interceptors.add(new ConnectInterceptor(client));         if (!forWebSocket) {             interceptors.addAll(client.networkInterceptors());         }         interceptors.add(new CallServerInterceptor(forWebSocket));           Interceptor.Chain chain = new RealInterceptorChain(interceptors, null, null, null, 0,                 originalRequest, this, eventListener, client.connectTimeoutMillis(),                 client.readTimeoutMillis(), client.writeTimeoutMillis());           return chain.proceed(originalRequest);     }

　　RealInterceptorChain实现拦截器功能  分别调用拦截器的proceed()方法执行网络请求返回Response

 

Dispatcher

　　Call看完接着进入HttpClient的Dispatcher的enqueue方法

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//准备中的异步队列     private final Deque<RealCall.AsyncCall> readyAsyncCalls = new ArrayDeque<>();     //执行中的异步队列     private final Deque<RealCall.AsyncCall> runningAsyncCalls = new ArrayDeque<>();     //执行中的同步队列     private final Deque<RealCall> runningSyncCalls = new ArrayDeque<>();           void enqueue(RealCall.AsyncCall call) {         synchronized (this) {             readyAsyncCalls.add(call);         }         //处理和执行线程         promoteAndExecute();     }           private boolean promoteAndExecute() {         assert (!Thread.holdsLock(this));         List<RealCall.AsyncCall> executableCalls = new ArrayList<>();         boolean isRunning;         synchronized (this) {//将线程进行缓存处理             for (Iterator<RealCall.AsyncCall> i = readyAsyncCalls.iterator(); i.hasNext(); ) {                 //从readyAsyncCalls中取出可执行线程并添加到runningAsyncCalls中 并执行线程                 RealCall.AsyncCall asyncCall = i.next();                 if (runningAsyncCalls.size() >= maxRequests) break; // Max capacity.                 if (runningCallsForHost(asyncCall) >= maxRequestsPerHost) continue; // Host max capacity.                 i.remove();                 executableCalls.add(asyncCall);                 runningAsyncCalls.add(asyncCall);             }             isRunning = runningCallsCount() > 0;         }           for (int i = 0, size = executableCalls.size(); i < size; i++) {             RealCall.AsyncCall asyncCall = executableCalls.get(i);             //调用RealCall的executeOn方法  其内部执行 executorService.execute(this);线程池启动线程             asyncCall.executeOn(executorService());         }           return isRunning;     }

　　关于Dispatcher内部的线程池--线程池另外写一个随笔

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public synchronized ExecutorService executorService() {        if (executorService == null) {            //创建一个线程池            executorService = new ThreadPoolExecutor(0, Integer.MAX_VALUE, 60, TimeUnit.SECONDS,                    new SynchronousQueue<Runnable>(), Util.threadFactory("OkHttp Dispatcher", false));        }        return executorService;    }

　　

 

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复制

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fun okhttp3Demo() {         val client: OkHttpClient = OkHttpClient.Builder().build()//创建OkHttpClient         val r: Request = Request.Builder().url("").build()//创建Request请求         val call:okhttp3.Call = client.newCall(r)//创建一个Call         //添加回调并且添加到等待缓存         call.enqueue(object : okhttp3.Callback {             override fun onFailure(call: okhttp3.Call, e: IOException) {               }               override fun onResponse(call: okhttp3.Call, response: okhttp3.Response) {               }         })         //call.execute()//直接加入运行缓存     }

　　

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fun okhttp3Demo() {         val client: OkHttpClient = OkHttpClient.Builder().build()//创建OkHttpClient         val r: Request = Request.Builder().url("").build()//创建Request请求         val call:okhttp3.Call = client.newCall(r)//创建一个Call         //添加回调并且添加到等待缓存         call.enqueue(object : okhttp3.Callback {             override fun onFailure(call: okhttp3.Call, e: IOException) {               }               override fun onResponse(call: okhttp3.Call, response: okhttp3.Response) {               }         })         //call.execute()//直接加入运行缓存     }