OkHttp学习(六) 3.10.0版本源码中的拦截器
系列文章
OkHttp学习(一) OSI七层模型和TCP四层模型
OkHttp学习(二) 3.10.0版本的简单使用及其流程梳理
OkHttp学习(三) 3.10.0版本源码阅读之线程池
OkHttp学习(四) 3.10.0版本源码阅读之构建者设计模式
OkHttp学习(五) 3.10.0版本源码阅读之责任链设计模式
OkHttp学习(六) 3.10.0版本源码中的拦截器
OkHttp学习(七) 手写OkHttp之框架搭建
OkHttp学习(八) 手写OkHttp之网络请求实现
OkHttp学习(九) OkHttp的连接池手写实现
整体架构
上篇文章我们已经分析了各个拦截器是如何串成一条链的，下面就分析链的每个节点都做了什么事情。
RetryAndFollowUpInterceptor
重试与重定向拦截器
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
RealInterceptorChain realChain = (RealInterceptorChain) chain;
Call call = realChain.call();
EventListener eventListener = realChain.eventListener();
// 创建资源分配器
StreamAllocation streamAllocation = new StreamAllocation(client.connectionPool(),
createAddress(request.url()), call, eventListener, callStackTrace);
this.streamAllocation = streamAllocation;
int followUpCount = 0;
Response priorResponse = null;
// 循环重试，如果成功直接跳出循环，如果失败，要么重试要么抛出异常，重试最大次数为20
while (true) {
if (canceled) {
streamAllocation.release();
throw new IOException("Canceled");
}
Response response;
boolean releaseConnection = true;
try {
// 从下个责任链节点中取的响应，传入了资源分配器
response = realChain.proceed(request, streamAllocation, null, null);
releaseConnection = false;
} catch (RouteException e) {
// The attempt to connect via a route failed. The request will not have been sent.
if (!recover(e.getLastConnectException(), streamAllocation, false, request)) {
throw e.getLastConnectException();
}
// 重试
releaseConnection = false;
continue;
} catch (IOException e) {
// An attempt to communicate with a server failed. The request may have been sent.
boolean requestSendStarted = !(e instanceof ConnectionShutdownException);
if (!recover(e, streamAllocation, requestSendStarted, request)) throw e;
releaseConnection = false;
// 重试
continue;
} finally {
// We're throwing an unchecked exception. Release any resources.
if (releaseConnection) {
streamAllocation.streamFailed(null);
streamAllocation.release();
}
}
// Attach the prior response if it exists. Such responses never have a body.
// 之前执行得到的priorResponse ，如果不为空，则会根据之前的priorResponse 重新创建response
if (priorResponse != null) {
response = response.newBuilder()
.priorResponse(priorResponse.newBuilder()
.body(null)
.build())
.build();
}
// 根据response判断是否需要重定向，重定向的reques不为空t会放到下次重试中
Request followUp = followUpRequest(response, streamAllocation.route());
// 重定向request为空，直接返回response
if (followUp == null) {
if (!forWebSocket) {
streamAllocation.release();
}
return response;
}
closeQuietly(response.body());
if (++followUpCount > MAX_FOLLOW_UPS) {
streamAllocation.release();
throw new ProtocolException("Too many follow-up requests: " + followUpCount);
}
if (followUp.body() instanceof UnrepeatableRequestBody) {
streamAllocation.release();
throw new HttpRetryException("Cannot retry streamed HTTP body", response.code());
}
if (!sameConnection(response, followUp.url())) {
streamAllocation.release();
streamAllocation = new StreamAllocation(client.connectionPool(),
createAddress(followUp.url()), call, eventListener, callStackTrace);
this.streamAllocation = streamAllocation;
} else if (streamAllocation.codec() != null) {
throw new IllegalStateException("Closing the body of " + response
+ " didn't close its backing stream. Bad interceptor?");
}
request = followUp;
priorResponse = response;
}
}
1.创建了StreamAllocation对象，该对象用于分配资源，后面会用到
2.调用下一个拦截器，得到response
3.根据异常结果或者响应结果判断是否要进行重试。
4.重定向的次数根据++followUpCount > MAX_FOLLOW_UPS判断不超过20次
4.对response进行处理，返回给上一个拦截器。
-
核心功能就是 连接失败重试(Retry)
- 在发生 RouteException 或者 IOException后，会捕获建联或者读取的一些异常，根据一定的策略判断是否是可恢复的，如果可恢复会重新创建 StreamAllocation开始新的一轮请求
-
继续发起请求(Follow up)
- 主要有这几种类型
- 3xx 重定向
- 401，407 未授权，调用 Authenticator进行授权后继续发起新的请求
- 408 客户端请求超时，如果 Request 的请求体没有被UnrepeatableRequestBody 标记，会继续发起新的请求
- 主要有这几种类型
BridgeInterceptor
public Response intercept(Chain chain) throws IOException {
Request userRequest = chain.request();
Request.Builder requestBuilder = userRequest.newBuilder();
RequestBody body = userRequest.body();
// 设置Content-Type
if (body != null) {
MediaType contentType = body.contentType();
if (contentType != null) {
requestBuilder.header("Content-Type", contentType.toString());
}
// Content-Length和Transfer-Encoding互斥
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");
}
}
// 设置Host
if (userRequest.header("Host") == null) {
requestBuilder.header("Host", hostHeader(userRequest.url(), false));
}
// 设置Connection头
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");
}
// 创建Okhpptclitent时候配置的cookieJar，
List cookies = cookieJar.loadForRequest(userRequest.url());
if (!cookies.isEmpty()) {
// 解析成http协议的cookie格式
requestBuilder.header("Cookie", cookieHeader(cookies));
}
if (userRequest.header("User-Agent") == null) {
requestBuilder.header("User-Agent", Version.userAgent());
}
// 从下个链节点中取的response
Response networkResponse = chain.proceed(requestBuilder.build());
// 响应header， 如果没有自定义配置cookieJar==null，则什么都不做
HttpHeaders.receiveHeaders(cookieJar, userRequest.url(), networkResponse.headers());
// copy一份从下个节点取的的response
Response.Builder responseBuilder = networkResponse.newBuilder()
.request(userRequest);
// 判断服务器是否支持gzip压缩格式,如果支持则交给okio压缩
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");
// 处理完成后，重新生成一个response
responseBuilder.body(new RealResponseBody(contentType, -1L, Okio.buffer(responseBody)));
}
// 将响应的response返回给上个拦截器
return responseBuilder.build();
}
BridgeInterceptor负责在request阶段对请求头添加一些字段，在response阶段对响应进行一些gzip解压操作。
1.负责将用户构建的Request请求转化为能够进行网络访问的请求
2.将这个符合网络请求的Request进行网络请求
3.将网络请求回来的Response转化为用户可用的Response，包括gzip压缩和gzip解压
CacheInterceptor
缓存拦截器
public Response intercept(Chain chain) throws IOException {
//1. 读取候选缓存；
Response cacheCandidate = cache != null
? cache.get(chain.request())
: null;
// 计时开始时间
long now = System.currentTimeMillis();
//2. 创建缓存策略（强制缓存，对比缓存等策略)；
CacheStrategy strategy = new CacheStrategy.Factory(now, chain.request(), cacheCandidate).get();
Request networkRequest = strategy.networkRequest;
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.
}
//根据策略，不使用网络，缓存又没有直接报错；
// If we're forbidden from using the network and the cache is insufficient, fail.
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();
}
// 4. 根据策略，不使用网络，有缓存就直接返回；
// If we don't need the network, we're done.
if (networkRequest == null) {
return cacheResponse.newBuilder()
.cacheResponse(stripBody(cacheResponse))
.build();
}
Response networkResponse = null;
try {
// 执行下个拦截器,获得网络response
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());
}
}
// 判断是否有缓存,如果有缓存,而且下个拦截器返回的response的code为304未修改,则使用缓存
// If we have a cache response too, then we're doing a conditional get.
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();
cache.update(cacheResponse, response);
return response;
} else {
closeQuietly(cacheResponse.body());
}
}
// 从下个拦截器中获取到的response中读取信息
Response response = networkResponse.newBuilder()
.cacheResponse(stripBody(cacheResponse))
.networkResponse(stripBody(networkResponse))
.build();
// 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);
}
// 删除无效缓存
if (HttpMethod.invalidatesCache(networkRequest.method())) {
try {
cache.remove(networkRequest);
} catch (IOException ignored) {
// The cache cannot be written.
}
}
}
// 返回到上个拦截器
return response;
}
- 读取候选缓存；
- 创建缓存策略（根据头信息，判断强制缓存，对比缓存等策略)；
- 根据策略，不使用网络，缓存又没有直接报错；
- 根据策略，不使用网络，有缓存就直接返回；
- 前面个都没有返回，读取网络结果（跑下一个拦截器）；
- 接收到的网络结果，如果是code 304, 使用缓存，返回缓存结果（对比缓存）
- 读取网络结果；
- 对数据进行缓存；删除无效缓存；
- 返回网络读取的结果。
ConnectInterceptor
ConnectInterceptor负责网络连接，其本质是复用连接池中socket连接。
public Response intercept(Chain chain) throws IOException {
RealInterceptorChain realChain = (RealInterceptorChain) chain;
Request request = realChain.request();
//从拦截器链里得到StreamAllocation对象
StreamAllocation streamAllocation = realChain.streamAllocation();
// We need the network to satisfy this request. Possibly for validating a conditional GET.
boolean doExtensiveHealthChecks = !request.method().equals("GET");
//创建连接等一系列的操作
HttpCodec httpCodec = streamAllocation.newStream(client, chain, doExtensiveHealthChecks);
//这里是获取前一步的connection.
RealConnection connection = streamAllocation.connection();
//把前面创建的连接，传递到下一个拦截器
return realChain.proceed(request, streamAllocation, httpCodec, connection);
}
1.StreamAllocation 这里的是在RetryAndFollowUpInterceptor拦截器中构造的包含网络请求所有组件的StreamAllocation流分配对象，一步一步传递过来的。
2.HttpCodec对象用来编码request，解码response的 。
3.RealConnection 用来进行实际的io网络传输。
4.会将HttpCodec和RealConnection 传递给后面的拦截器使用。
StreamAllocation
首先，StreamAllocation的初始化在第一个拦截器RetryAndFollowUpInterceptor里面，
streamAllocation = new StreamAllocation(
client.connectionPool(), createAddress(request.url()), callStackTrace);
传入了三个参数，一个连接池，一个地址类，一个调用堆栈跟踪相关的。
在StreamAllocation构造函数中，主要是把这个三个参数保存为内部变量，供后面使用。
该构造器里面有两个重要的参数：
1.使用了Okhttp的连接池ConnectionPool
2.通过url创建了一个Address对象。
Okhttp连接池简单说明： 本篇只是对连接池做最简单的说明，内部的实现原理暂时不细讲。在Okhttp内部的连接池实现类为ConnectionPool，该类持有一个ArrayDeque队列作为缓存池，该队列里的元素为RealConnection(通过这个名字应该不难猜出RealConnection是来干嘛的）。该链接池在初始化OkhttpClient对象的时候由OkhttpClient的Builder类创建，并且ConnectionPool提供了put、get、evictAll等操作。但是Okhttp并没有直接对连接池进行获取，插入等操作；而是专门提供了一个叫Internal的抽象类来操作缓冲池：比如向缓冲池里面put一个RealConnection，从缓冲池get一个RealConnection对象，该类里面有一个public且为static的Internal类型的引用：
//抽象类
public abstract class Internal {
public static Internal instance;
}1234
instance的初始化是在OkhttpClient的static语句块完成的：
static {
Internal.instance = new Internal() {
//省略部分代码
};
}
newStream()方法
主要做了如下工作：
1）从缓冲池ConnectionPool获取一个RealConnection对象，如果缓冲池里面没有就创建一个RealConnection对象并且放入缓冲池中，具体的说是放入ConnectionPool的ArrayDeque队列中。
2）获取RealConnection对象后并调用其connect（打开Socket链接）。下面具体分析：
public HttpCodec newStream(OkHttpClient client, boolean doExtensiveHealthChecks) {
//1. 获取设置的连接超时时间，读写超时的时间，以及是否进行重连。
int connectTimeout = client.connectTimeoutMillis();
int readTimeout = client.readTimeoutMillis();
int writeTimeout = client.writeTimeoutMillis();
boolean connectionRetryEnabled = client.retryOnConnectionFailure();
try {
// 2. 获取健康可用的连接
RealConnection resultConnection = findHealthyConnection(connectTimeout, readTimeout,
writeTimeout, connectionRetryEnabled, doExtensiveHealthChecks);
//3. 通过resultConnection初始化，对请求以及结果 编解码的类（分http 1.1 和http 2.0）。
// 这里主要是初始化，在后面一个拦截器才用到这相关的东西。
HttpCodec resultCodec = resultConnection.newCodec(client, this);
synchronized (connectionPool) {
codec = resultCodec;
return resultCodec;
}
} catch (IOException e) {
throw new RouteException(e);
}
}
获取连接
findHealthyConnection()
private RealConnection findHealthyConnection(int connectTimeout, int readTimeout,
int writeTimeout, boolean connectionRetryEnabled, boolean doExtensiveHealthChecks)
throws IOException {
// 1. 加了个死循环，一直找可用的连接
while (true) {
// 2. 这里继续去挖掘，寻找连接
RealConnection candidate = findConnection(connectTimeout, readTimeout, writeTimeout,
connectionRetryEnabled);
// 3. 连接池同步获取，上面找到的连接是否是一个新的连接，如果是的话，就直接返回了，就是我们需要找
// 的连接了
// If this is a brand new connection, we can skip the extensive health checks.
synchronized (connectionPool) {
if (candidate.successCount == 0) {
return candidate;
}
}
//4. 如果不是一个新的连接，那么通过判断，是否一个可用的连接。
// 里面是通过Socket的一些方法进行判断的，有兴趣的，可以继续研究一下
// 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)) {
noNewStreams();
continue;
}
return candidate;
}
}
findConnection
/**
* 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,
boolean connectionRetryEnabled) throws IOException {
Route selectedRoute;
// 1. 同步线程池，来获取里面的连接
synchronized (connectionPool) {
// 2. 异常的处理。做些判断，是否已经释放，是否编解码类为空，是否用户已经取消 if (released) throw new IllegalStateException("released");
if (codec != null) throw new IllegalStateException("codec != null");
if (canceled) throw new IOException("Canceled");
// 3. 尝试用一下现在的连接，判断一下，是否有可用的连接。（使用已存在的连接）
// Attempt to use an already-allocated connection.
RealConnection allocatedConnection = this.connection;
if (allocatedConnection != null && !allocatedConnection.noNewStreams) {
return allocatedConnection;
}
// 4. 尝试在连接池中获取一个连接，get方法中会直接调用，注意最后一个参数为空
// 里面是一个for循环，在连接池里面，寻找合格的连接
// 而合格的连接会通过，StreamAllocation中的acquire方法，更新connection的值。（从缓存中获取）
// Attempt to get a connection from the pool.
Internal.instance.get(connectionPool, address, this, null);
if (connection != null) {
return connection;
}
selectedRoute = route;
}
//5. 判断上面得到的线路，是否空，如果为空的，寻找一个可用的线路
// 对于线路的选，可以深究一下这个RouteSeletor
// 线路的选择，多ip的支持 if (selectedRoute == null) {
selectedRoute = routeSelector.next();// 里面又个神奇的递归
}
RealConnection result;
//6. 以上都不符合，创建一个连接
synchronized (connectionPool) {
if (canceled) throw new IOException("Canceled");
// 7. 由于上面我们获取了一个线路，无论是新建的，或者已有的。
// 我们通过这个线路，继续在连接池中寻找是否有可用的连接。
// Now that we have an IP address, make another attempt at getting a connection from the pool.
// This could match due to connection coalescing.
Internal.instance.get(connectionPool, address, this, selectedRoute);
if (connection != null) return connection;
// 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.
route = selectedRoute;
refusedStreamCount = 0;
// 8. 如果前面这么寻找，都没在连接池中找打可用的连接，那么就新建一个
result = new RealConnection(connectionPool, selectedRoute);
acquire(result);
}
// 9. 这里就是就是连接的操作了，终于找到连接的正主了，这里会调用RealConnection的连接方法，进行连接操作。
// 如果是普通的http请求，会使用Socket进行连接
// 如果是https，会进行相应的握手，建立通道的操作。
// 这里就不对里面的操作进行详细分析了，有兴趣可以在进去看看
// Do TCP + TLS handshakes. This is a blocking operation.
result.connect(connectTimeout, readTimeout, writeTimeout, connectionRetryEnabled);
routeDatabase().connected(result.route());
Socket socket = null;
// 10. 最后就是同步加到 连接池里面了
synchronized (connectionPool) {
// Pool the connection.
Internal.instance.put(connectionPool, result);
// 最后加了一个多路复用的判断，这个是http2才有的
// If another multiplexed connection to the same address was created concurrently, then
// release this connection and acquire that one.
if (result.isMultiplexed()) {
socket = Internal.instance.deduplicate(connectionPool, address, this);
result = connection;
}
}
closeQuietly(socket);
return result;
}
建立连接
建立连接是比较重要的一步了。如果是Https还有证书步骤
public void connect(
int connectTimeout, int readTimeout, int writeTimeout, boolean connectionRetryEnabled) {
if (protocol != null) throw new IllegalStateException("already connected");
// 线路的选择
RouteException routeException = null;
List connectionSpecs = route.address().connectionSpecs();
ConnectionSpecSelector connectionSpecSelector = new ConnectionSpecSelector(connectionSpecs);
if (route.address().sslSocketFactory() == null) {
if (!connectionSpecs.contains(ConnectionSpec.CLEARTEXT)) {
throw new RouteException(new UnknownServiceException(
"CLEARTEXT communication not enabled for client"));
}
String host = route.address().url().host();
if (!Platform.get().isCleartextTrafficPermitted(host)) {
throw new RouteException(new UnknownServiceException(
"CLEARTEXT communication to " + host + " not permitted by network security policy"));
}
}
// 连接开始
while (true) {
try {
// 如果要求通道模式，建立通道连接，通常不是这种
if (route.requiresTunnel()) {
connectTunnel(connectTimeout, readTimeout, writeTimeout);
} else {
// 一般都走这条逻辑了，实际上很简单就是socket的连接
connectSocket(connectTimeout, readTimeout);
}
// https的建立
establishProtocol(connectionSpecSelector);
break;
} catch (IOException e) {
closeQuietly(socket);
closeQuietly(rawSocket);
socket = null;
rawSocket = null;
source = null;
sink = null;
handshake = null;
protocol = null;
http2Connection = null;
if (routeException == null) {
routeException = new RouteException(e);
} else {
routeException.addConnectException(e);
}
if (!connectionRetryEnabled || !connectionSpecSelector.connectionFailed(e)) {
throw routeException;
}
}
}
if (http2Connection != null) {
synchronized (connectionPool) {
allocationLimit = http2Connection.maxConcurrentStreams();
}
}
}
connectSocket
private void connectSocket(int connectTimeout, int readTimeout) throws IOException {
Proxy proxy = route.proxy();
Address address = route.address();
// 根据代理类型处理socket，为true
rawSocket = proxy.type() == Proxy.Type.DIRECT || proxy.type() == Proxy.Type.HTTP
? address.socketFactory().createSocket()
: new Socket(proxy);
rawSocket.setSoTimeout(readTimeout);
try {
// 连接socket，之所以这样写是因为支持不同的平台
/**
* 里面实际上是 socket.connect(address, connectTimeout);
*
*/
Platform.get().connectSocket(rawSocket, route.socketAddress(), connectTimeout);
} catch (ConnectException e) {
ConnectException ce = new ConnectException("Failed to connect to " + route.socketAddress());
ce.initCause(e);
throw ce;
}
// 得到输入／输出流
source = Okio.buffer(Okio.source(rawSocket));
sink = Okio.buffer(Okio.sink(rawSocket));
}
如果使用的是https协议，并且配置有真实将会协议升级。
Https协议的建立 connectTls
如果使用的是https协议socket连接完成后还有一步，就是Tls的处理
private void connectTls(ConnectionSpecSelector connectionSpecSelector) throws IOException {
Address address = route.address();
SSLSocketFactory sslSocketFactory = address.sslSocketFactory();
boolean success = false;
SSLSocket sslSocket = null;
try {
// 在原来socket上加一层ssl
// Create the wrapper over the connected socket.
sslSocket = (SSLSocket) sslSocketFactory.createSocket(
rawSocket, address.url().host(), address.url().port(), true /* autoClose */);
// Configure the socket's ciphers, TLS versions, and extensions.
ConnectionSpec connectionSpec = connectionSpecSelector.configureSecureSocket(sslSocket);
if (connectionSpec.supportsTlsExtensions()) {
Platform.get().configureTlsExtensions(
sslSocket, address.url().host(), address.protocols());
}
// Force handshake. This can throw!
sslSocket.startHandshake();
Handshake unverifiedHandshake = Handshake.get(sslSocket.getSession());
// Verify that the socket's certificates are acceptable for the target host.
if (!address.hostnameVerifier().verify(address.url().host(), sslSocket.getSession())) {
X509Certificate cert = (X509Certificate) unverifiedHandshake.peerCertificates().get(0);
throw new SSLPeerUnverifiedException("Hostname " + address.url().host() + " not verified:"
+ "\n certificate: " + CertificatePinner.pin(cert)
+ "\n DN: " + cert.getSubjectDN().getName()
+ "\n subjectAltNames: " + OkHostnameVerifier.allSubjectAltNames(cert));
}
// Check that the certificate pinner is satisfied by the certificates presented.
address.certificatePinner().check(address.url().host(),
unverifiedHandshake.peerCertificates());
// Success! Save the handshake and the ALPN protocol.
String maybeProtocol = connectionSpec.supportsTlsExtensions()
? Platform.get().getSelectedProtocol(sslSocket)
: null;
socket = sslSocket;
source = Okio.buffer(Okio.source(socket));
sink = Okio.buffer(Okio.sink(socket));
handshake = unverifiedHandshake;
protocol = maybeProtocol != null
? Protocol.get(maybeProtocol)
: Protocol.HTTP_1_1;
success = true;
} catch (AssertionError e) {
if (Util.isAndroidGetsocknameError(e)) throw new IOException(e);
throw e;
} finally {
if (sslSocket != null) {
Platform.get().afterHandshake(sslSocket);
}
if (!success) {
closeQuietly(sslSocket);
}
}
}
CallServerInterceptor
public Response intercept(Chain chain) throws IOException {
// 省略部分代码
// 获取HttpCodec
HttpCodec httpCodec = realChain.httpStream();
// 省略部分代码
Request request = realChain.request();
//向服务器发送请求
httpCodec.writeRequestHeaders(request);
Response.Builder responseBuilder = null;
// 检测是否有请求body
if (HttpMethod.permitsRequestBody(request.method()) && request.body() != null) {
if ("100-continue".equalsIgnoreCase(request.header("Expect"))) {
httpCodec.flushRequest();
//构建responseBuilder对象
responseBuilder = httpCodec.readResponseHeaders(true);
}
//如果服务器允许发送请求body发送
if (responseBuilder == null) {
Sink requestBodyOut = httpCodec.createRequestBody(request, request.body().contentLength());
BufferedSink bufferedRequestBody = Okio.buffer(requestBodyOut);
request.body().writeTo(bufferedRequestBody);
bufferedRequestBody.close();
} else if (!connection.isMultiplexed()) {
//省略部分代码
}
}
//结束请求
httpCodec.finishRequest();
//构建请求buidder对象
if (responseBuilder == null) {
responseBuilder = httpCodec.readResponseHeaders(false);
}
Response response = responseBuilder
.request(request)
.handshake(streamAllocation.connection().handshake())
.sentRequestAtMillis(sentRequestMillis)
.receivedResponseAtMillis(System.currentTimeMillis())
.build();
int code = response.code();
if (forWebSocket && code == 101) {
//省略部分代码
} else {
response = response.newBuilder()
.body(httpCodec.openResponseBody(response))
.build();
}
//省略部分代码
return response;
}
CallServerInterceptor的主要功能就是—向服务器发送请求，并最终返回Response对象供客户端使用。
总结
RetryAndFollowUpInterceptor：这个拦截器它的作用主要是负责请求的重定向操作，用于处理网络请求中，请求失败后的重试机制。
BridgeInterceptor：BridgeInterceptor负责在request阶段对请求头添加一些字段，在response阶段对响应进行一些gzip解压操作。
CacheInterceptor：用来实现响应缓存。比如获取到的 Response 带有 Date，Expires，Last-Modified，Etag 等 header，表示该 Response 可以缓存一定的时间，下次请求就可以不需要发往服务端，直接拿缓存的
ConnectInterceptor：ConnectInterceptor负责网络连接，其本质是复用连接池中socket连接。
CallServerInterceptor：CallServerInterceptor的主要功能就是—向服务器发送请求，并最终返回Response对象供客户端使用。