OkHttp源码解析(二)——整体流程（下）

1.前言

这一篇将说一下请求体的写入以及相应的读取过程。

2.请求体写入过程

HttpEngine#readResponse

这个方法下有下面的一块代码片段。

<code class="hljs bash has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (!<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">caller</span>WritesRequestBody) {      networkResponse = new NetworkInterceptorChain(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>, networkRequest,          streamAllocation.connection()).proceed(networkRequest);    } </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>

callerWritesRequestBody在初始化的时候为false,我们接着看NetworkInterceptorChain的proceed方法，会发现下面一段代码。

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">      if (permitsRequestBody(request) && request<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.body</span>() != null) {        Sink requestBodyOut = httpStream<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.createRequestBody</span>(request, request<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.body</span>()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.contentLength</span>())<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>        BufferedSink bufferedRequestBody = Okio<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.buffer</span>(requestBodyOut)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>        request<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.body</span>()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.writeTo</span>(bufferedRequestBody)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>        bufferedRequestBody<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.close</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>      }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>

• permitsRequestBody 判断是否允许body

• 判断body是否为空

这里返回的requestBodyOut对象是对我们创建socket的时候的那个sike对象的包装。这里我偷个懒，具体的代码就不贴了。感兴趣的去http1xstream下追踪看看。这样，我们就把请求体也写入进去了。

3.读取响应的过程

HttpEngine#readNetworkResponse 
在该方法中，有下面代码片段。

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">    Response networkResponse = httpStream<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.readResponseHeaders</span>()        <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.request</span>(networkRequest)        <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.handshake</span>(streamAllocation<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.connection</span>()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.handshake</span>())        <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.sentRequestAtMillis</span>(sentRequestMillis)        <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.receivedResponseAtMillis</span>(System<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.currentTimeMillis</span>())        <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.build</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>    if (!forWebSocket) {      networkResponse = networkResponse<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.newBuilder</span>()          <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.body</span>(httpStream<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.openResponseBody</span>(networkResponse))          <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.build</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>    }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>

我们重点关注httpStream.openResponseBody方法。

4.Http1xStream

Http1xStream#openResponseBody，该方法如下。

<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">  <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> ResponseBody <span class="hljs-title" style="box-sizing: border-box;">openResponseBody</span>(Response response) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">throws</span> IOException {    Source source = getTransferStream(response);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> RealResponseBody(response.headers(), Okio.buffer(source));  }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>

在getTransferStream方法中，通过层层的调用，构造出一个Source对象，并将其和response.headers组装成真正的响应体。

5.Http2XStream

Http2xStream#openResponseBody

<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">  <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> ResponseBody <span class="hljs-title" style="box-sizing: border-box;">openResponseBody</span>(Response response) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">throws</span> IOException {    Source source = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> StreamFinishingSource(stream.getSource());    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> RealResponseBody(response.headers(), Okio.buffer(source));  }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>

看到，关键点在于stream.getSource，而这个stream是什么呢？这是一个FramedStrem对象，并且是在writeRequestHeaders方法中初始化的。相应代码如下

<code class="hljs fix has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-attribute" style="box-sizing: border-box;">stream </span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;"> framedConnection.newStream(requestHeaders, permitsRequestBody, hasResponseBody);</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

而framedConnection是在HttpStrem#newStream方法中初始化并传入的

<code class="hljs cs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">resultStream = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Http2xStream(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>, resultConnection.framedConnection);</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

而resultConnection.framedConnection则是RealConnection的framedConnection了，这个对象是在什么时候初始化的呢？是在建立连接的时候，在establishProtocol方法中。

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">    if (protocol == Protocol<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.SPDY</span>_3 || protocol == Protocol<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.HTTP</span>_2) {      socket<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setSoTimeout</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">; // Framed connection timeouts are set per-stream.</span>      FramedConnection framedConnection = new FramedConnection<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.Builder</span>(true)          <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.socket</span>(socket, route<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.address</span>()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.url</span>()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.host</span>(), source, sink)          <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.protocol</span>(protocol)          <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.listener</span>(this)          <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.build</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>      framedConnection<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.start</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>      // Only assign the framed connection once the preface has been sent successfully.      this<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.allocationLimit</span> = framedConnection<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.maxConcurrentStreams</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>      this<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.framedConnection</span> = framedConnection<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>    } else {      this<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.allocationLimit</span> = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>    }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li></ul>

注意，上面讲socket，source，sink都传了进去。 
现实new了一个对象，病start，并且把这个对象传给RealConnection的framedConnection。因此，我们看下start方法干了什么，

<code class="hljs sql has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"> new Thread(readerRunnable).<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">start</span>();</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

<code class="hljs axapta has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">readerRunnable = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Reader(variant.newReader(builder.source, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">client</span>));</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

这里的Reader是一个Runnable是一个实现NamedRunnable的对象没我们需要看下他的execute方法。

<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">    <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">execute</span>() {      ErrorCode connectionErrorCode = ErrorCode.INTERNAL_ERROR;      ErrorCode streamErrorCode = ErrorCode.INTERNAL_ERROR;      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (!client) {          frameReader.readConnectionPreface();        }        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">while</span> (frameReader.nextFrame(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>)) {        }        connectionErrorCode = ErrorCode.NO_ERROR;        streamErrorCode = ErrorCode.CANCEL;      } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (IOException e) {        connectionErrorCode = ErrorCode.PROTOCOL_ERROR;        streamErrorCode = ErrorCode.PROTOCOL_ERROR;      } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">finally</span> {        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {          close(connectionErrorCode, streamErrorCode);        } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (IOException ignored) {        }        Util.closeQuietly(frameReader);      }    }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li></ul>

可以在while里看到frameReader.nextFrame(this)，而这个framewReader是Http2的Reader对象，我们看下他的方法。

<code class="hljs fix has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-attribute" style="box-sizing: border-box;">variant </span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;"> new Http2();</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

<code class="hljs axapta has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">    Reader(BufferedSource source, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> headerTableSize, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">client</span>) {      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.source = source;      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">client</span> = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">client</span>;      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.continuation = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ContinuationSource(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.source);      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.hpackReader = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Hpack.Reader(headerTableSize, continuation);    }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li></ul>

而在在nextFrame方法里，我们就能看到读取的过程了。代码片段如下。

<code class="hljs markdown has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">最后来张截图压压惊。![<span class="hljs-link_label" style="box-sizing: border-box;">这里写图片描述</span>](<span class="hljs-link_url" style="box-sizing: border-box;">http://img.blog.csdn.net/20160728000306967</span>)</code>