okhttp是支持http1.0，http1.1，http2.0，spdy协议
okhttp发起请求
反编译okhttp-3.4.1.jar版本代码看到http2和http1
public HttpStream newStream(OkHttpClient client, boolean doExtensiveHealthChecks) {
int connectTimeout = client.connectTimeoutMillis();
int readTimeout = client.readTimeoutMillis();
int writeTimeout = client.writeTimeoutMillis();
boolean connectionRetryEnabled = client.retryOnConnectionFailure();
try {
RealConnection resultConnection = this.findHealthyConnection(connectTimeout, readTimeout, writeTimeout, connectionRetryEnabled, doExtensiveHealthChecks);
Object resultStream;
if(resultConnection.framedConnection != null) {
resultStream = new Http2xStream(client, this, resultConnection.framedConnection);
} else {
resultConnection.socket().setSoTimeout(readTimeout);
resultConnection.source.timeout().timeout((long)readTimeout, TimeUnit.MILLISECONDS);
resultConnection.sink.timeout().timeout((long)writeTimeout, TimeUnit.MILLISECONDS);
resultStream = new Http1xStream(client, this, resultConnection.source, resultConnection.sink);
}
ConnectionPool var9 = this.connectionPool;
synchronized(this.connectionPool) {
this.stream = (HttpStream)resultStream;
return (HttpStream)resultStream;
}
} catch (IOException var12) {
throw new RouteException(var12);
}
}
