OkHttp 异步网络请求流程

 直接上码:

	public void doGet(View view) {

		Request request = new Request.Builder().url(BASEURL + "login")
				.get().cacheControl(CacheControl.FORCE_NETWORK).build();
		okHttpClient.newCall(request).enqueue(new Callback() {
			@Override
			public void onFailure(Call call, IOException e) {
				Log.e(TAG, "onFailure: " + call.toString());
			}

			@Override
			public void onResponse(Call call, Response response) throws IOException {
				Log.e(TAG, "onResponse: " + response.body().string());
			}
		});
	}public void doGet(View view) {

		Request request = new Request.Builder().url(BASEURL + "login")
				.get().cacheControl(CacheControl.FORCE_NETWORK).build();
		okHttpClient.newCall(request).enqueue(new Callback() {
			@Override
			public void onFailure(Call call, IOException e) {
				Log.e(TAG, "onFailure: " + call.toString());
			}

			@Override
			public void onResponse(Call call, Response response) throws IOException {
				Log.e(TAG, "onResponse: " + response.body().string());
			}
		});
	}

跟使用同步方法是相差一个enqueque()方法:

  @Override public void enqueue(Callback responseCallback) {
    synchronized (this) {
      if (executed) throw new IllegalStateException("Already Executed");
      executed = true;
    }
    captureCallStackTrace();
    eventListener.callStart(this);
    client.dispatcher().enqueue(new AsyncCall(responseCallback)); 创建一个ASyncCall 对象交给 dispather
  }

 dispathcher.enqueque(...) :

synchronized void enqueue(AsyncCall call) {
判断网络请求进行中数量是否大于最大请求和 ip(域名)相同不超过maxRequestsPerHost 
 if (runningAsyncCalls.size() < maxRequests && runningCallsForHost(call) < maxRequestsPerHost) {
runningAsyncCalls.add(call);//符合 添加到异步运行容器中
 executorService().execute(call);// 然后线程池调度器去执行 call 
}
else 
{ 
readyAsyncCalls.add(call); //不符合添加到等待队列中
 }
 }

因为是使用executorService.execute(..) 参数是call  所以AsyncCall必然是继承Runable子类或者实现了Runable.

AsyncCall 继承的是 NamedRunable(Runable的子类) 并实现了抽象execute()方法

 @Override protected void execute() {
      boolean signalledCallback = false;
      try {
        Response response = getResponseWithInterceptorChain(); 去执行网络请求
        if (retryAndFollowUpInterceptor.isCanceled()) { 是否取消
          signalledCallback = true;
          responseCallback.onFailure(RealCall.this, new IOException("Canceled"));错误(取消)回调
        } else {
          signalledCallback = true;
          responseCallback.onResponse(RealCall.this, response);成功回调
        }
      } catch (IOException e) {
        if (signalledCallback) {
          // Do not signal the callback twice!
          Platform.get().log(INFO, "Callback failure for " + toLoggableString(), e);
        } else {
          eventListener.callFailed(RealCall.this, e);
          responseCallback.onFailure(RealCall.this, e);
        }
      } finally {
        client.dispatcher().finished(this); 这里是从异步容器中移除并判断是否有read..容器中网络请求有
添加到线程调度器中执行,没有或者大于最大请求 good bye
 }
    }
  }

Dispather: 存放AsyncCall和并使 AsyncCall 的中网络请求方法在子线程执行
流程图如下: