Request/Response
Request是发送请求封装类，内部有url，header， method，body等常见的参数，Response是请求的结果，包含code，message，header，body；这两个类的定义是完全符合Http协议所定义的请求内容和响应内容。
OkHttpClient
Call和WebSocket实例对象的一个工厂类，用于发送HTTP请求和读取响应。
OkHttpClient.Builder
内部类Builder用于构建OkHttpClient实例。其无参构造方法设置OkHttpClient的默认参数值,其方法设置OkHttpClient的特定参数值。
// Builer默认构造函数,OkHttpClient的默认参数都在这里设置
public Builder() {
dispatcher = new Dispatcher();
protocols = DEFAULT_PROTOCOLS;
connectionSpecs = DEFAULT_CONNECTION_SPECS;
eventListenerFactory = EventListener.factory(EventListener.NONE);
proxySelector = ProxySelector.getDefault();
if (proxySelector == null) {
proxySelector = new NullProxySelector();
}
cookieJar = CookieJar.NO_COOKIES;
socketFactory = SocketFactory.getDefault();
hostnameVerifier = OkHostnameVerifier.INSTANCE;
certificatePinner = CertificatePinner.DEFAULT;
proxyAuthenticator = Authenticator.NONE;
authenticator = Authenticator.NONE;
connectionPool = new ConnectionPool();
dns = Dns.SYSTEM;
followSslRedirects = true;
followRedirects = true;
retryOnConnectionFailure = true;
callTimeout = 0;
connectTimeout = 10_000;
readTimeout = 10_000;
writeTimeout = 10_000;
pingInterval = 0;
}
重要的方法
// 构造Call对象
@Override
public Call newCall(Request request) {
return RealCall.newRealCall(this, request, false /* for web socket */);
}
// 构造WebSocket对象
@Override
public WebSocket newWebSocket(Request request, WebSocketListener listener) {
RealWebSocket webSocket = new RealWebSocket(request, listener, new Random(), pingInterval);
webSocket.connect(this);
return webSocket;
}
RealCall
真正的Call的实现类。负责请求的调度（同步和异步，同步即是走当前线程发送请求，异步则使用OkHttp内部的线程池进行）；负责构造内部逻辑责任链，并执行责任链相关逻辑，知道获取结果。
重要的方法
// 真正构造RealCall对象的方法
static RealCall newRealCall(OkHttpClient client, Request originalRequest, boolean forWebSocket) {
// Safely publish the Call instance to the EventListener.
RealCall call = new RealCall(client, originalRequest, forWebSocket);
// 构造了Transimitter对象
call.transmitter = new Transmitter(client, call);
return call;
}
// 执行同步请求的方法
@Override
public Response execute() throws IOException {
synchronized (this) {
if (executed) throw new IllegalStateException("Already Executed");
executed = true;
}
transmitter.timeoutEnter();
transmitter.callStart();
try {
// 将同步的Call对象加入Dispatcher的runningSyncCalls队列中
client.dispatcher().executed(this);
// 重点在此处,OkHttpClient的责任链模式
return getResponseWithInterceptorChain();
} finally {
// 将同步的Call对象从Dispatcher的runningSyncCalls队列中删除// ,并寻找可以加入到Dispatcher的runningAsyncCalls队列中的
// AsyncCall对象,将其加入到线程池中等待执行。最后走OkHttpCl// ient的责任链模式.
client.dispatcher().finished(this);
}
}
// 执行异步请求的方法
@Override
public void enqueue(Callback responseCallback) {
synchronized (this) {
if (executed) throw new IllegalStateException("Already Executed");
executed = true;
}
transmitter.callStart();
// 构造异步的AsyncCall对象,将AsyncCall对象加入Dispatcher的
// readyAsyncCalls队列中
client.dispatcher().enqueue(new AsyncCall(responseCallback));
}
// 重点，走责任链模式
Response getResponseWithInterceptorChain() throws IOException {
// Build a full stack of interceptors.
// 构造Interceptor的集合
List<Interceptor> interceptors = new ArrayList<>();
// 自定义的interceptors,被称为application interceptors
interceptors.addAll(client.interceptors());
interceptors.add(new RetryAndFollowUpInterceptor(client));
interceptors.add(new BridgeInterceptor(client.cookieJar()));
interceptors.add(new CacheInterceptor(client.internalCache()));
interceptors.add(new ConnectInterceptor(client));
if (!forWebSocket) {
// 自定义的interceptors,被称为network interceptors
interceptors.addAll(client.networkInterceptors());
}
interceptors.add(new CallServerInterceptor(forWebSocket));
// 用上面的集合构造责任链对象,并传递index进去,index决定了责任链的哪一个interceptors
Interceptor.Chain chain = new RealInterceptorChain(interceptors, transmitter, null, 0,
originalRequest, this, client.connectTimeoutMillis(),
client.readTimeoutMillis(), client.writeTimeoutMillis());
boolean calledNoMoreExchanges = false;
try {
// 责任链的proceed方法,开始责任链
Response response = chain.proceed(originalRequest);
if (transmitter.isCanceled()) {
closeQuietly(response);
throw new IOException("Canceled");
}
return response;
} catch (IOException e) {
calledNoMoreExchanges = true;
throw transmitter.noMoreExchanges(e);
} finally {
if (!calledNoMoreExchanges) {
transmitter.noMoreExchanges(null);
}
}
}
Interceptor（OkHttp的核心）
RetryAndFollowUpInterceptor（失败和重定向拦截器）
重要的方法
@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
RealInterceptorChain realChain = (RealInterceptorChain) chain;
Transmitter transmitter = realChain.transmitter();
int followUpCount = 0;
Response priorResponse = null;
while (true) {
// 为发送数据做准备,会创建ExchangeFinder对象,为后面获取exchange对象做准备
transmitter.prepareToConnect(request);
if (transmitter.isCanceled()) {
throw new IOException("Canceled");
}
Response response;
boolean success = false;
try {
// 下一责任链
response = realChain.proceed(request, transmitter, null);
success = true;
} catch (RouteException e) {
// The attempt to connect via a route failed. The request will not have been sent.
// 是否发生Route类型的异常,如果有,判断是否满足重试条件,满足则continue重试,重试的逻辑在recover方法中
if (!recover(e.getLastConnectException(), transmitter, false, request)) {
throw e.getFirstConnectException();
}
continue;
} catch (IOException e) {
// An attempt to communicate with a server failed. The request may have been sent.
// 是否发生IO类型的异常,如果有,判断是否满足重试条件,满足则continue重试
boolean requestSendStarted = !(e instanceof ConnectionShutdownException);
if (!recover(e, transmitter, requestSendStarted, request)) throw e;
continue;
} finally {
// The network call threw an exception. Release any resources.
if (!success) {
transmitter.exchangeDoneDueToException();
}
}
// Attach the prior response if it exists. Such responses never have a body.
if (priorResponse != null) {
response = response.newBuilder()
.priorResponse(priorResponse.newBuilder()
.body(null)
.build())
.build();
}
Exchange exchange = Internal.instance.exchange(response);
Route route = exchange != null ? exchange.connection().route() : null;
// 这里处理是否重定向的逻辑并开始构造重定向请求,具体情况看源码分析
Request followUp = followUpRequest(response, route);
if (followUp == null) {
if (exchange != null && exchange.isDuplex()) {
transmitter.timeoutEarlyExit();
}
return response;
}
RequestBody followUpBody = followUp.body();
if (followUpBody != null && followUpBody.isOneShot()) {
return response;
}
closeQuietly(response.body());
if (transmitter.hasExchange()) {
exchange.detachWithViolence();
}
if (++followUpCount > MAX_FOLLOW_UPS) {
throw new ProtocolException("Too many follow-up requests: " + followUpCount);
}
request = followUp;
priorResponse = response;
}
}
Interceptors和NetworkInterceptors的区别
在 OkHttpClient.Builder 中，使用者可以通过 addInterceptor 和 addNetworkdInterceptor 添加自定义的拦截器，分析完 RetryAndFollowUpInterceptor 就可以知道这两种自动拦截器的区别了。
从添加拦截器的顺序可以知道 Interceptors 和 networkInterceptors 刚好一个在 RetryAndFollowUpInterceptor 的前面，一个在后面。
可以分析出来，假如一个请求在 RetryAndFollowUpInterceptor 这个拦截器内部重试或者重定向了 N 次，那么其内部嵌套的所有拦截器也会被调用N次，同样 networkInterceptors 自定义的拦截器也会被调用 N 次。而相对的 Interceptors 则一个请求只会调用一次，所以在OkHttp的内部也将其称之为 Application Interceptor。
BridgeInterceptor（封装request和response拦截器）
重要的方法
@Override
public Response intercept(Chain chain) throws IOException {
Request userRequest = chain.request();
Request.Builder requestBuilder = userRequest.newBuilder();
RequestBody body = userRequest.body();
if (body != null) {
MediaType contentType = body.contentType();
if (contentType != null) {
requestBuilder.header("Content-Type", contentType.toString());
}
long contentLength = body.contentLength();
if (contentLength != -1) {
requestBuilder.header("Content-Length", Long.toString(contentLength));
requestBuilder.removeHeader("Transfer-Encoding");
} else {
requestBuilder.header("Transfer-Encoding", "chunked");
requestBuilder.removeHeader("Content-Length");
}
}
if (userRequest.header("Host") == null) {
requestBuilder.header("Host", hostHeader(userRequest.url(), false));
}
if (userRequest.header("Connection") == null) {
requestBuilder.header("Connection", "Keep-Alive");
}
// If we add an "Accept-Encoding: gzip" header field we're responsible for also decompressing
// the transfer stream.
boolean transparentGzip = false;
if (userRequest.header("Accept-Encoding") == null && userRequest.header("Range") == null) {
transparentGzip = true;
requestBuilder.header("Accept-Encoding", "gzip");
}
List<Cookie> cookies = cookieJar.loadForRequest(userRequest.url());
if (!cookies.isEmpty()) {
requestBuilder.header("Cookie", cookieHeader(cookies));
}
if (userRequest.header("User-Agent") == null) {
requestBuilder.header("User-Agent", Version.userAgent());
}
Response networkResponse = chain.proceed(requestBuilder.build());
HttpHeaders.receiveHeaders(cookieJar, userRequest.url(), networkResponse.headers());
Response.Builder responseBuilder = networkResponse.newBuilder()
.request(userRequest);
if (transparentGzip
&& "gzip".equalsIgnoreCase(networkResponse.header("Content-Encoding"))
&& HttpHeaders.hasBody(networkResponse)) {
GzipSource responseBody = new GzipSource(networkResponse.body().source());
Headers strippedHeaders = networkResponse.headers().newBuilder()
.removeAll("Content-Encoding")
.removeAll("Content-Length")
.build();
responseBuilder.headers(strippedHeaders);
String contentType = networkResponse.header("Content-Type");
responseBuilder.body(new RealResponseBody(contentType, -1L, Okio.buffer(responseBody)));
}
return responseBuilder.build();
}
这个拦截器比较简单,功能如下:
- 负责把用户构造的请求转换为发送到服务器的请求 、把服务器返回的响应转换为用户友好的响应，是从应用程序代码到网络代码的桥梁
- 设置内容长度，内容编码
- 设置gzip压缩，并在接收到内容后进行解压。省去了应用层处理数据解压的麻烦
- 添加cookie
- 设置其他报头，如User-Agent,Host,Keep-alive等。其中Keep-Alive是实现连接复用的必要步骤
CacheInterceptor（缓存拦截器）
重要的方法
@Override
public Response intercept(Chain chain) throws IOException {
// 通过Request在Cache中拿缓存,前提是OkHttpClient中配置了缓存,默认不支持
Response cacheCandidate = cache != null
? cache.get(chain.request())
: null;
long now = System.currentTimeMillis();
// 根据response,time,request构造一个缓存策略，用于判断怎样使用缓存。
CacheStrategy strategy = new CacheStrategy.Factory(now, chain.request(), cacheCandidate).get();
// 如果该请求没有使用网络就为null
Request networkRequest = strategy.networkRequest;
// 如果该请求没有使用缓存则为空
Response cacheResponse = strategy.cacheResponse;
if (cache != null) {
cache.trackResponse(strategy);
}
if (cacheCandidate != null && cacheResponse == null) {
closeQuietly(cacheCandidate.body()); // The cache candidate wasn't applicable. Close it.
}
// If we're forbidden from using the network and the cache is insufficient, fail.
// 如果缓存策略中设置禁止使用网络，并且缓存也为空，则构建一个Response直接返回，注意返回码=504
if (networkRequest == null && cacheResponse == null) {
return new Response.Builder()
.request(chain.request())
.protocol(Protocol.HTTP_1_1)
.code(504)
.message("Unsatisfiable Request (only-if-cached)")
.body(Util.EMPTY_RESPONSE)
.sentRequestAtMillis(-1L)
.receivedResponseAtMillis(System.currentTimeMillis())
.build();
}
// If we don't need the network, we're done.
// 如果不使用网络但有缓存,则返回缓存
if (networkRequest == null) {
return cacheResponse.newBuilder()
.cacheResponse(stripBody(cacheResponse))
.build();
}
Response networkResponse = null;
try {
// 走后续拦截器流程
networkResponse = chain.proceed(networkRequest);
} finally {
// If we're crashing on I/O or otherwise, don't leak the cache body.
if (networkResponse == null && cacheCandidate != null) {
closeQuietly(cacheCandidate.body());
}
}
// If we have a cache response too, then we're doing a conditional get.
// 缓存存在且网络返回的Response为304,则使用缓存的Response
if (cacheResponse != null) {
if (networkResponse.code() == HTTP_NOT_MODIFIED) {
Response response = cacheResponse.newBuilder()
.headers(combine(cacheResponse.headers(), networkResponse.headers()))
.sentRequestAtMillis(networkResponse.sentRequestAtMillis())
.receivedResponseAtMillis(networkResponse.receivedResponseAtMillis())
.cacheResponse(stripBody(cacheResponse))
.networkResponse(stripBody(networkResponse))
.build();
networkResponse.body().close();
// Update the cache after combining headers but before stripping the
// Content-Encoding header (as performed by initContentStream()).
cache.trackConditionalCacheHit();
// 更新缓存
cache.update(cacheResponse, response);
return response;
} else {
closeQuietly(cacheResponse.body());
}
}
// 构建网络请求的Resposne
Response response = networkResponse.newBuilder()
.cacheResponse(stripBody(cacheResponse))
.networkResponse(stripBody(networkResponse))
.build();
// OkHttpClient中配置了Cache的话,缓存Response
if (cache != null) {
if (HttpHeaders.hasBody(response) && CacheStrategy.isCacheable(response, networkRequest)) {
// Offer this request to the cache.
CacheRequest cacheRequest = cache.put(response);
return cacheWritingResponse(cacheRequest, response);
}
if (HttpMethod.invalidatesCache(networkRequest.method())) {
try {
cache.remove(networkRequest);
} catch (IOException ignored) {
// The cache cannot be written.
}
}
}
return response;
}
ConnectInterceptor（网络连接拦截器,负责和服务器建立连接,重点，未完成）
重要的方法
@Override
public Response intercept(Chain chain) throws IOException {
RealInterceptorChain realChain = (RealInterceptorChain) chain;
Request request = realChain.request();
Transmitter transmitter = realChain.transmitter();
// We need the network to satisfy this request. Possibly for validating a conditional GET.
boolean doExtensiveHealthChecks = !request.method().equals("GET");
// 注释1 从Transmitter中获取新的Exchange对象
Exchange exchange = transmitter.newExchange(chain, doExtensiveHealthChecks);
return realChain.proceed(request, transmitter, exchange);
}
源码逻辑跳转:
// 源码位置: Transmitter.java
/** Returns a new exchange to carry a new request and response. */
Exchange newExchange(Interceptor.Chain chain, boolean doExtensiveHealthChecks) {
synchronized (connectionPool) {
if (noMoreExchanges) {
throw new IllegalStateException("released");
}
if (exchange != null) {
throw new IllegalStateException("cannot make a new request because the previous response "
+ "is still open: please call response.close()");
}
}
// 调用ExchangeFinder的find()获取ExchangeCodec
ExchangeCodec codec = exchangeFinder.find(client, chain, doExtensiveHealthChecks);
// 用上面获取的codec对象构建新的Exchange对象
Exchange result = new Exchange(this, call, eventListener, exchangeFinder, codec);
synchronized (connectionPool) {
this.exchange = result;
this.exchangeRequestDone = false;
this.exchangeResponseDone = false;
return result;
}
}
// 源码位置: ExchangFinder.java
public ExchangeCodec find(
OkHttpClient client, Interceptor.Chain chain, boolean doExtensiveHealthChecks) {
int connectTimeout = chain.connectTimeoutMillis();
int readTimeout = chain.readTimeoutMillis();
int writeTimeout = chain.writeTimeoutMillis();
int pingIntervalMillis = client.pingIntervalMillis();
boolean connectionRetryEnabled = client.retryOnConnectionFailure();
try {
// 调用自身findHealthyConnection方法获取RealConnection
RealConnection resultConnection = findHealthyConnection(connectTimeout, readTimeout,
writeTimeout, pingIntervalMillis, connectionRetryEnabled, doExtensiveHealthChecks);
return resultConnection.newCodec(client, chain);
} catch (RouteException e) {
trackFailure();
throw e;
} catch (IOException e) {
trackFailure();
throw new RouteException(e);
}
}
// 源码位置: ExchangeFinder.java
/**
* Finds a connection and returns it if it is healthy. If it is unhealthy the process is repeated
* until a healthy connection is found.
*/
private RealConnection findHealthyConnection(int connectTimeout, int readTimeout,
int writeTimeout, int pingIntervalMillis, boolean connectionRetryEnabled,
boolean doExtensiveHealthChecks) throws IOException {
while (true) {
// 在ExchangeFinder的findConnection方法循环获取可用的RealConnection
RealConnection candidate = findConnection(connectTimeout, readTimeout, writeTimeout,
pingIntervalMillis, connectionRetryEnabled);
// If this is a brand new connection, we can skip the extensive health checks.
synchronized (connectionPool) {
// 判断获取的RealConnection是否可用,若可用返回,不可用继续寻找
if (candidate.successCount == 0 && !candidate.isMultiplexed()) {
return candidate;
}
}
// Do a (potentially slow) check to confirm that the pooled connection is still good. If it
// isn't, take it out of the pool and start again.
if (!candidate.isHealthy(doExtensiveHealthChecks)) {
candidate.noNewExchanges();
continue;
}
return candidate;
}
}
// 源码位置: ExchangeFinder.java
/**
* Returns a connection to host a new stream. This prefers the existing connection if it exists,
* then the pool, finally building a new connection.
*/
private RealConnection findConnection(int connectTimeout, int readTimeout, int writeTimeout,
int pingIntervalMillis, boolean connectionRetryEnabled) throws IOException {
boolean foundPooledConnection = false;
RealConnection result = null;
Route selectedRoute = null;
RealConnection releasedConnection;
Socket toClose;
synchronized (connectionPool) {
if (transmitter.isCanceled()) throw new IOException("Canceled");
hasStreamFailure = false; // This is a fresh attempt.
// Attempt to use an already-allocated connection. We need to be careful here because our
// already-allocated connection may have been restricted from creating new exchanges.
// 尝试使用已分配的连接,已经分配的连接可能已经被限制创建新的流
releasedConnection = transmitter.connection;
toClose = transmitter.connection != null && transmitter.connection.noNewExchanges
? transmitter.releaseConnectionNoEvents()
: null;
if (transmitter.connection != null) {
// We had an already-allocated connection and it's good.
// 已分配连接,并且该连接可用
result = transmitter.connection;
releasedConnection = null;
}
if (result == null) {
// Attempt to get a connection from the pool.
// 尝试从连接池中获取一个连接
if (connectionPool.transmitterAcquirePooledConnection(address, transmitter, null, false)) {
foundPooledConnection = true;
result = transmitter.connection;
} else if (nextRouteToTry != null) {
selectedRoute = nextRouteToTry;
nextRouteToTry = null;
} else if (retryCurrentRoute()) {
selectedRoute = transmitter.connection.route();
}
}
}
// 关闭连接
closeQuietly(toClose);
if (releasedConnection != null) {
eventListener.connectionReleased(call, releasedConnection);
}
if (foundPooledConnection) {
eventListener.connectionAcquired(call, result);
}
if (result != null) {
// If we found an already-allocated or pooled connection, we're done.
// 如果已经从连接池中获取到了一个连接，就将其返回
return result;
}
// If we need a route selection, make one. This is a blocking operation.
boolean newRouteSelection = false;
if (selectedRoute == null && (routeSelection == null || !routeSelection.hasNext())) {
newRouteSelection = true;
routeSelection = routeSelector.next();
}
List<Route> routes = null;
synchronized (connectionPool) {
if (transmitter.isCanceled()) throw new IOException("Canceled");
if (newRouteSelection) {
// Now that we have a set of IP addresses, make another attempt at getting a connection from
// the pool. This could match due to connection coalescing.
// 根据一系列的 IP 地址从连接池中获取一个链接
routes = routeSelection.getAll();
if (connectionPool.transmitterAcquirePooledConnection(
address, transmitter, routes, false)) {
foundPooledConnection = true;
result = transmitter.connection;
}
}
if (!foundPooledConnection) {
if (selectedRoute == null) {
selectedRoute = routeSelection.next();
}
// Create a connection and assign it to this allocation immediately. This makes it possible
// for an asynchronous cancel() to interrupt the handshake we're about to do.
// 创建一个新的连接，并将其分配，这样我们就可以在握手之前进行终端
result = new RealConnection(connectionPool, selectedRoute);
connectingConnection = result;
}
}
// If we found a pooled connection on the 2nd time around, we're done.
// 如果我们在第二次的时候发现了一个池连接，那么我们就将其返回
if (foundPooledConnection) {
eventListener.connectionAcquired(call, result);
return result;
}
// Do TCP + TLS handshakes. This is a blocking operation.
// 进行 TCP 和 TLS 握手
result.connect(connectTimeout, readTimeout, writeTimeout, pingIntervalMillis,
connectionRetryEnabled, call, eventListener);
connectionPool.routeDatabase.connected(result.route());
Socket socket = null;
synchronized (connectionPool) {
connectingConnection = null;
// Last attempt at connection coalescing, which only occurs if we attempted multiple
// concurrent connections to the same host.
if (connectionPool.transmitterAcquirePooledConnection(address, transmitter, routes, true)) {
// We lost the race! Close the connection we created and return the pooled connection.
result.noNewExchanges = true;
socket = result.socket();
result = transmitter.connection;
// It's possible for us to obtain a coalesced connection that is immediately unhealthy. In
// that case we will retry the route we just successfully connected with.
nextRouteToTry = selectedRoute;
} else {
connectionPool.put(result);
transmitter.acquireConnectionNoEvents(result);
}
}
closeQuietly(socket);
eventListener.connectionAcquired(call, result);
return result;
}
注释1处(跟源码)内部逻辑如下:
- ConnectInterceptor调用transmitter.newExchange
- Transmitter先调用ExchangeFinder的find()获得ExchangeCodec
- ExchangeFinder调用自身的findHealthyConnection获得RealConnection
- ExchangeFinder的findHealthyConnection方法调用自身的findConnection获得RealConnection
- ExchangeFinder通过刚才获取的RealConnection的codec()方法获得ExchangeCodec
- Transmitter获取到了ExchangeCodec，然后new了一个ExChange，将刚才的ExchangeCodec包含在内。
通过上面的逻辑,ConnectInterceptor可以获得一个Exchange类,这个类有两个实现,一个是Http1ExchangeCodec,一个是Http2ExchangeCodec,分别对应Http1和Http2协议。
Exchange类里面包含了ExchangeCodec对象，而这个对象里面又包含了一个RealConnection对象，RealConnection的属性成员有socket、handlShake、protocol等，可见它应该是一个Socket连接的包装类，而ExchangeCode对象是对RealConnection操作（writeRequestHeader、readResposneHeader）的封装。
CallServerInterceptor（执行流操作拦截器,负责向服务器发送请求数据、从服务器读取响应数据 进行http请求报文的封装与请求报文的解析）
重要的方法
@Override
public Response intercept(Chain chain) throws IOException {
RealInterceptorChain realChain = (RealInterceptorChain) chain;
Exchange exchange = realChain.exchange();
Request request = realChain.request();
long sentRequestMillis = System.currentTimeMillis();
// 写入请求头
exchange.writeRequestHeaders(request);
boolean responseHeadersStarted = false;
Response.Builder responseBuilder = null;
if (HttpMethod.permitsRequestBody(request.method()) && request.body() != null) {
// If there's a "Expect: 100-continue" header on the request, wait for a "HTTP/1.1 100
// Continue" response before transmitting the request body. If we don't get that, return
// what we did get (such as a 4xx response) without ever transmitting the request body.
if ("100-continue".equalsIgnoreCase(request.header("Expect"))) {
exchange.flushRequest();
responseHeadersStarted = true;
exchange.responseHeadersStart();
responseBuilder = exchange.readResponseHeaders(true);
}
// 写入请求体
if (responseBuilder == null) {
if (request.body().isDuplex()) {
// Prepare a duplex body so that the application can send a request body later.
exchange.flushRequest();
BufferedSink bufferedRequestBody = Okio.buffer(
exchange.createRequestBody(request, true));
request.body().writeTo(bufferedRequestBody);
} else {
// Write the request body if the "Expect: 100-continue" expectation was met.
BufferedSink bufferedRequestBody = Okio.buffer(
exchange.createRequestBody(request, false));
request.body().writeTo(bufferedRequestBody);
bufferedRequestBody.close();
}
} else {
exchange.noRequestBody();
if (!exchange.connection().isMultiplexed()) {
// If the "Expect: 100-continue" expectation wasn't met, prevent the HTTP/1 connection
// from being reused. Otherwise we're still obligated to transmit the request body to
// leave the connection in a consistent state.
exchange.noNewExchangesOnConnection();
}
}
} else {
exchange.noRequestBody();
}
if (request.body() == null || !request.body().isDuplex()) {
exchange.finishRequest();
}
if (!responseHeadersStarted) {
exchange.responseHeadersStart();
}
if (responseBuilder == null) {
// 读取响应头
responseBuilder = exchange.readResponseHeaders(false);
}
Response response = responseBuilder
.request(request)
.handshake(exchange.connection().handshake())
.sentRequestAtMillis(sentRequestMillis)
.receivedResponseAtMillis(System.currentTimeMillis())
.build();
int code = response.code();
if (code == 100) {
// server sent a 100-continue even though we did not request one.
// try again to read the actual response
response = exchange.readResponseHeaders(false)
.request(request)
.handshake(exchange.connection().handshake())
.sentRequestAtMillis(sentRequestMillis)
.receivedResponseAtMillis(System.currentTimeMillis())
.build();
code = response.code();
}
exchange.responseHeadersEnd(response);
if (forWebSocket && code == 101) {
// Connection is upgrading, but we need to ensure interceptors see a non-null response body.
response = response.newBuilder()
.body(Util.EMPTY_RESPONSE)
.build();
} else {
// 读取响应体
response = response.newBuilder()
.body(exchange.openResponseBody(response))
.build();
}
if ("close".equalsIgnoreCase(response.request().header("Connection"))
|| "close".equalsIgnoreCase(response.header("Connection"))) {
exchange.noNewExchangesOnConnection();
}
if ((code == 204 || code == 205) && response.body().contentLength() > 0) {
throw new ProtocolException(
"HTTP " + code + " had non-zero Content-Length: " + response.body().contentLength());
}
return response;
}
CallServerInterceptor由以下步骤组成:
- 向服务器发送 request header
- 如果有 request body，就向服务器发送
- 读取 response header，先构造一个 Response 对象
- 如果有 response body，就在 3 的基础上加上 body 构造一个新的 Response 对象
