OkHttp的性能指標攔截（首包，剩餘包時間，resultCode）

最近，部門接到新的任務就是作httpClient,URLConnection,OKhttpClient，webview的網絡性能指標進行監控，固然這些指標最準確的方法仍是使用jni在底層建鏈與dns解析，發包等函數進行hook，再進行指標採集。但領導要求咱們在java層嘗試一下，今天主要記錄下，我對OkHttp網絡指標採集的調研結果和嘗試。

1   OkHttpClient client = new OkHttpClient();
2   Request request = new Request.Builder().url(url).get().build();
3   Response response = client.newCall(request).execute();

 對於httpClient咱們通嘗都是替換execute（）方法，而後對httpClient的對像進行更改配置本身的攔截功能，查看源碼，發現OkHttpClient相對不一樣的是execute方法並不在OkHttpClient，而是newCall方法中new 了一個call實例。

1 public Call newCall(Request request) {
2     return new Call(this, request);
3   }

//Call構造器中，對OkHttpClient進行了深拷備，因此對newCall以後的OkHttpClient配置都將沒法生效，因此咱們必須在newCall以前將攔截代碼進行塞入
 Call(OkHttpClient client, Request originalRequest) {
  // Copy the client. Otherwise changes (socket factory, redirect policy,
  // etc.) may incorrectly be reflected in the request when it is
  // executed.
  this.client = client.copyWithDefaults();
  this.originalRequest = originalRequest;
 }

發現Call類並非final的，因此決定對其繼承，由於 Call的構造器是protected的，因此子類須要在相同的包名下，而上層的攔截因而這樣實現的

1   public static Call newCall(OkHttpClient okHttpClient, Request paramRequest)
2     {
3       return new MyCall(okHttpClient, paramRequest, okHttpClient.newCall(paramRequest));
4     }

MyCall類的中的public,protected方法進行重寫（execute()，enqueue(Callback paramCallback)，cancel()，isCanceled()），實現使用傳入的call進行調用，重寫getResponse方法

 1  @Override
 2         Response getResponse(Request request, boolean forWebSocket) throws IOException {
 3             RequestBody body = request.body();
 4             if (body != null) {
 5                 Request.Builder requestBuilder = request.newBuilder();
 6 
 7                 MediaType contentType = body.contentType();
 8                 if (contentType != null) {
 9                     requestBuilder.header("Content-Type", contentType.toString());
10                 }
11 
12                 long contentLength = body.contentLength();
13                 if (contentLength != -1) {
14                     requestBuilder.header("Content-Length", Long.toString(contentLength));
15                     requestBuilder.removeHeader("Transfer-Encoding");
16                 } else {
17                     requestBuilder.header("Transfer-Encoding", "chunked");
18                     requestBuilder.removeHeader("Content-Length");
19                 }
20 
21                 request = requestBuilder.build();
22             }
23 
24             // Create the initial HTTP engine. Retries and redirects need new engine
25             // for each attempt.
26             engine = new HttpEngine(client, request, false, false, forWebSocket, null, null, null, null);
27 
28             int followUpCount = 0;
29             while (true) {
30                 if (canceled) {
31                     engine.releaseConnection();
32                     throw new IOException("Canceled");
33                 }
34 
35                 try {
36                     Timer requestTime = ThreadLocalMetricsRecorder.getInstance().getRequestTimer();
37                     Timer responseTime = ThreadLocalMetricsRecorder.getInstance().getResponseTimer();
38                     requestTime.start();
39                     engine.sendRequest();
40                     requestTime.stop();
41                     responseTime.start();
42                     engine.readResponse();
43                     responseTime.stop();
44                 } catch (RequestException e) {
45                     // The attempt to interpret the request failed. Give up.
46                     throw e.getCause();
47                 } catch (RouteException e) {
48                     // The attempt to connect via a route failed. The request will
49                     // not have been sent.
50                     HttpEngine retryEngine = engine.recover(e);
51                     if (retryEngine != null) {
52                         engine = retryEngine;
53                         continue;
54                     }
55                     // Give up; recovery is not possible.
56                     throw e.getLastConnectException();
57                 } catch (IOException e) {
58                     // An attempt to communicate with a server failed. The request
59                     // may have been sent.
60                     HttpEngine retryEngine = engine.recover(e, null);
61                     if (retryEngine != null) {
62                         engine = retryEngine;
63                         continue;
64                     }
65 
66                     // Give up; recovery is not possible.
67                     throw e;
68                 }
69 
70                 Response response = engine.getResponse();
71                 Request followUp = engine.followUpRequest();
72 
73                 if (followUp == null) {
74                     if (!forWebSocket) {
75                         engine.releaseConnection();
76                     }
77                     return response;
78                 }
79 
80                 if (++followUpCount > MAX_FOLLOW_UPS) {
81                     throw new ProtocolException("Too many follow-up requests: " + followUpCount);
82                 }
83 
84                 if (!engine.sameConnection(followUp.url())) {
85                     engine.releaseConnection();
86                 }
87 
88                 Connection connection = engine.close();
89                 request = followUp;
90                 engine = new HttpEngine(client, request, false, false, forWebSocket, connection, null, null, response);
91             }
92         }

算出首包,剩餘包時間和攔截重定向，經過重寫enqueue方法，獲取清求的錯誤與response

 1         @Override
 2         public void enqueue(Callback paramCallback)
 3         {
 4 //          a();
 5           this.e.enqueue(new Callback() {
 6             
 7             @Override
 8             public void onResponse(Response response) throws IOException {
 9                 
10             }
11             
12             @Override
13             public void onFailure(Request request, IOException e) {
14                 
15             }
16         });
17         }