我們學習技術的時候，一開始是會用，進階就是深入理解其原理，然而各路框架源碼，系統源碼又極爲龐大，我們就必須知道如何去領會其中的核心思想。今天我們就一起來理一理OkHttp的核心源碼，做到知其然知其所以然！
OKHttp的使用：
OkHttpClient okHttpClient = new OkHttpClient();
一開始我們需要初始化OkHttpClient，這裏使用的是一個無參構造，我們進去看下構造函數的實現：
public OkHttpClient() {
this(new Builder());
}
可見，在無參構造初始化OkhttpClient對象時，初始化了一個新的對象Builder，我們一起來看看這個Builder到底是什麼：
public static final class Builder {
Dispatcher dispatcher;
Proxy proxy;
List<Protocol> protocols;
List<ConnectionSpec> connectionSpecs;
final List<Interceptor> interceptors = new ArrayList<>();
final List<Interceptor> networkInterceptors = new ArrayList<>();
ProxySelector proxySelector;
CookieJar cookieJar;
Cache cache;
InternalCache internalCache;
SocketFactory socketFactory;
SSLSocketFactory sslSocketFactory;
TrustRootIndex trustRootIndex;
HostnameVerifier hostnameVerifier;
CertificatePinner certificatePinner;
Authenticator proxyAuthenticator;
Authenticator authenticator;
ConnectionPool connectionPool;
Dns dns;
boolean followSslRedirects;
boolean followRedirects;
boolean retryOnConnectionFailure;
int connectTimeout;
int readTimeout;
int writeTimeout;
public Builder() {
dispatcher = new Dispatcher();
protocols = DEFAULT_PROTOCOLS;
connectionSpecs = DEFAULT_CONNECTION_SPECS;
proxySelector = ProxySelector.getDefault();
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;
connectTimeout = 10_000;
readTimeout = 10_000;
writeTimeout = 10_000;
}
Builder(OkHttpClient okHttpClient) {
this.dispatcher = okHttpClient.dispatcher;
this.proxy = okHttpClient.proxy;
this.protocols = okHttpClient.protocols;
this.connectionSpecs = okHttpClient.connectionSpecs;
this.interceptors.addAll(okHttpClient.interceptors);
this.networkInterceptors.addAll(okHttpClient.networkInterceptors);
this.proxySelector = okHttpClient.proxySelector;
this.cookieJar = okHttpClient.cookieJar;
this.internalCache = okHttpClient.internalCache;
this.cache = okHttpClient.cache;
this.socketFactory = okHttpClient.socketFactory;
this.sslSocketFactory = okHttpClient.sslSocketFactory;
this.trustRootIndex = okHttpClient.trustRootIndex;
this.hostnameVerifier = okHttpClient.hostnameVerifier;
this.certificatePinner = okHttpClient.certificatePinner;
this.proxyAuthenticator = okHttpClient.proxyAuthenticator;
this.authenticator = okHttpClient.authenticator;
this.connectionPool = okHttpClient.connectionPool;
this.dns = okHttpClient.dns;
this.followSslRedirects = okHttpClient.followSslRedirects;
this.followRedirects = okHttpClient.followRedirects;
this.retryOnConnectionFailure = okHttpClient.retryOnConnectionFailure;
this.connectTimeout = okHttpClient.connectTimeout;
this.readTimeout = okHttpClient.readTimeout;
this.writeTimeout = okHttpClient.writeTimeout;
}
public Builder connectTimeout(long timeout, TimeUnit unit) {
if (timeout < 0) throw new IllegalArgumentException("timeout < 0");
if (unit == null) throw new IllegalArgumentException("unit == null");
long millis = unit.toMillis(timeout);
if (millis > Integer.MAX_VALUE) throw new IllegalArgumentException("Timeout too large.");
if (millis == 0 && timeout > 0) throw new IllegalArgumentException("Timeout too small.");
connectTimeout = (int) millis;
return this;
}
public Builder readTimeout(long timeout, TimeUnit unit) {
if (timeout < 0) throw new IllegalArgumentException("timeout < 0");
if (unit == null) throw new IllegalArgumentException("unit == null");
long millis = unit.toMillis(timeout);
if (millis > Integer.MAX_VALUE) throw new IllegalArgumentException("Timeout too large.");
if (millis == 0 && timeout > 0) throw new IllegalArgumentException("Timeout too small.");
readTimeout = (int) millis;
return this;
}
public Builder writeTimeout(long timeout, TimeUnit unit) {
if (timeout < 0) throw new IllegalArgumentException("timeout < 0");
if (unit == null) throw new IllegalArgumentException("unit == null");
long millis = unit.toMillis(timeout);
if (millis > Integer.MAX_VALUE) throw new IllegalArgumentException("Timeout too large.");
if (millis == 0 && timeout > 0) throw new IllegalArgumentException("Timeout too small.");
writeTimeout = (int) millis;
return this;
}
public Builder proxy(Proxy proxy) {
this.proxy = proxy;
return this;
}
public Builder proxySelector(ProxySelector proxySelector) {
this.proxySelector = proxySelector;
return this;
}
public Builder cookieJar(CookieJar cookieJar) {
if (cookieJar == null) throw new NullPointerException("cookieJar == null");
this.cookieJar = cookieJar;
return this;
}
/** Sets the response cache to be used to read and write cached responses. */
void setInternalCache(InternalCache internalCache) {
this.internalCache = internalCache;
this.cache = null;
}
public Builder cache(Cache cache) {
this.cache = cache;
this.internalCache = null;
return this;
}
public Builder dns(Dns dns) {
if (dns == null) throw new NullPointerException("dns == null");
this.dns = dns;
return this;
}
public Builder socketFactory(SocketFactory socketFactory) {
if (socketFactory == null) throw new NullPointerException("socketFactory == null");
this.socketFactory = socketFactory;
return this;
}
public Builder sslSocketFactory(SSLSocketFactory sslSocketFactory) {
if (sslSocketFactory == null) throw new NullPointerException("sslSocketFactory == null");
this.sslSocketFactory = sslSocketFactory;
this.trustRootIndex = null;
return this;
}
public Builder hostnameVerifier(HostnameVerifier hostnameVerifier) {
if (hostnameVerifier == null) throw new NullPointerException("hostnameVerifier == null");
this.hostnameVerifier = hostnameVerifier;
return this;
}
public Builder certificatePinner(CertificatePinner certificatePinner) {
if (certificatePinner == null) throw new NullPointerException("certificatePinner == null");
this.certificatePinner = certificatePinner;
return this;
}
public Builder authenticator(Authenticator authenticator) {
if (authenticator == null) throw new NullPointerException("authenticator == null");
this.authenticator = authenticator;
return this;
}
public Builder proxyAuthenticator(Authenticator proxyAuthenticator) {
if (proxyAuthenticator == null) throw new NullPointerException("proxyAuthenticator == null");
this.proxyAuthenticator = proxyAuthenticator;
return this;
}
public Builder connectionPool(ConnectionPool connectionPool) {
if (connectionPool == null) throw new NullPointerException("connectionPool == null");
this.connectionPool = connectionPool;
return this;
}
public Builder followRedirects(boolean followRedirects) {
this.followRedirects = followRedirects;
return this;
}
public Builder retryOnConnectionFailure(boolean retryOnConnectionFailure) {
this.retryOnConnectionFailure = retryOnConnectionFailure;
return this;
}
public Builder dispatcher(Dispatcher dispatcher) {
if (dispatcher == null) throw new IllegalArgumentException("dispatcher == null");
this.dispatcher = dispatcher;
return this;
}
public Builder protocols(List<Protocol> protocols) {
protocols = Util.immutableList(protocols);
if (!protocols.contains(Protocol.HTTP_1_1)) {
throw new IllegalArgumentException("protocols doesn't contain http/1.1: " + protocols);
}
if (protocols.contains(Protocol.HTTP_1_0)) {
throw new IllegalArgumentException("protocols must not contain http/1.0: " + protocols);
}
if (protocols.contains(null)) {
throw new IllegalArgumentException("protocols must not contain null");
}
this.protocols = Util.immutableList(protocols);
return this;
}
public Builder connectionSpecs(List<ConnectionSpec> connectionSpecs) {
this.connectionSpecs = Util.immutableList(connectionSpecs);
return this;
}
public List<Interceptor> interceptors() {
return interceptors;
}
public Builder addInterceptor(Interceptor interceptor) {
interceptors.add(interceptor);
return this;
}
public List<Interceptor> networkInterceptors() {
return networkInterceptors;
}
public Builder addNetworkInterceptor(Interceptor interceptor) {
networkInterceptors.add(interceptor);
return this;
}
public OkHttpClient build() {
return new OkHttpClient(this);
}
}
Builder是OkHttpClient的一個靜態內部類，通過new Builder()完成Builder對象的一些成員變量的初始化：
public Builder() {
dispatcher = new Dispatcher();
protocols = DEFAULT_PROTOCOLS;
connectionSpecs = DEFAULT_CONNECTION_SPECS;
proxySelector = ProxySelector.getDefault();
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;
connectTimeout = 10_000;
readTimeout = 10_000;
writeTimeout = 10_000;
}
我們再來看this(new Builder()):
private OkHttpClient(Builder builder) {
this.dispatcher = builder.dispatcher;
this.proxy = builder.proxy;
this.protocols = builder.protocols;
this.connectionSpecs = builder.connectionSpecs;
this.interceptors = Util.immutableList(builder.interceptors);
this.networkInterceptors = Util.immutableList(builder.networkInterceptors);
this.proxySelector = builder.proxySelector;
this.cookieJar = builder.cookieJar;
this.cache = builder.cache;
this.internalCache = builder.internalCache;
this.socketFactory = builder.socketFactory;
boolean isTLS = false;
for (ConnectionSpec spec : connectionSpecs) {
isTLS = isTLS || spec.isTls();
}
if (builder.sslSocketFactory != null || !isTLS) {
this.sslSocketFactory = builder.sslSocketFactory;
} else {
try {
SSLContext sslContext = SSLContext.getInstance("TLS");
sslContext.init(null, null, null);
this.sslSocketFactory = sslContext.getSocketFactory();
} catch (GeneralSecurityException e) {
throw new AssertionError(); // The system has no TLS. Just give up.
}
}
if (sslSocketFactory != null && builder.trustRootIndex == null) {
X509TrustManager trustManager = Platform.get().trustManager(sslSocketFactory);
if (trustManager == null) {
throw new IllegalStateException("Unable to extract the trust manager on " + Platform.get()
+ ", sslSocketFactory is " + sslSocketFactory.getClass());
}
this.trustRootIndex = Platform.get().trustRootIndex(trustManager);
this.certificatePinner = builder.certificatePinner.newBuilder()
.trustRootIndex(trustRootIndex)
.build();
} else {
this.trustRootIndex = builder.trustRootIndex;
this.certificatePinner = builder.certificatePinner;
}
this.hostnameVerifier = builder.hostnameVerifier;
this.proxyAuthenticator = builder.proxyAuthenticator;
this.authenticator = builder.authenticator;
this.connectionPool = builder.connectionPool;
this.dns = builder.dns;
this.followSslRedirects = builder.followSslRedirects;
this.followRedirects = builder.followRedirects;
this.retryOnConnectionFailure = builder.retryOnConnectionFailure;
this.connectTimeout = builder.connectTimeout;
this.readTimeout = builder.readTimeout;
this.writeTimeout = builder.writeTimeout;
}
可見，通過初始化好的Builder對象屬性給OkHttpClient對象屬性賦值。
有時候我們也可以這樣調用：
OkHttpClient okHttpClient = new OkHttpClient.Builder()
.connectTimeout(3,TimeUnit.SECONDS)
.writeTimeout(3,TimeUnit.SECONDS)
.readTimeout(3,TimeUnit.SECONDS)
.build();
開始初始化一個Builder對象，然後調用Builder對象裏面的方法重新設置一些屬性，最後在通過build方法初始化OKHttpClient對象。
public OkHttpClient build() {
return new OkHttpClient(this);
}
最後還是調用了OkHttpClient的有參構造，本質同上面一樣。
創建一個request請求：
Request request = new Request.Builder()
.url(Constants.GET_CURRENT_ANDROID_APP_VERSION_URL + url)
.build();
我們進Request源碼去看一看：
public final class Request {
private final HttpUrl url;
private final String method;
private final Headers headers;
private final RequestBody body;
private final Object tag;
private volatile URI javaNetUri; // Lazily initialized.
private volatile CacheControl cacheControl; // Lazily initialized.
private Request(Builder builder) {
this.url = builder.url;
this.method = builder.method;
this.headers = builder.headers.build();
this.body = builder.body;
this.tag = builder.tag != null ? builder.tag : this;
}
public HttpUrl url() {
return url;
}
public String method() {
return method;
}
public Headers headers() {
return headers;
}
public String header(String name) {
return headers.get(name);
}
public List<String> headers(String name) {
return headers.values(name);
}
public RequestBody body() {
return body;
}
public Object tag() {
return tag;
}
public Builder newBuilder() {
return new Builder(this);
}
/**
* Returns the cache control directives for this response. This is never null, even if this
* response contains no {@code Cache-Control} header.
*/
public CacheControl cacheControl() {
CacheControl result = cacheControl;
return result != null ? result : (cacheControl = CacheControl.parse(headers));
}
public boolean isHttps() {
return url.isHttps();
}
@Override public String toString() {
return "Request{method="
+ method
+ ", url="
+ url
+ ", tag="
+ (tag != this ? tag : null)
+ '}';
}
public static class Builder {
private HttpUrl url;
private String method;
private Headers.Builder headers;
private RequestBody body;
private Object tag;
public Builder() {
this.method = "GET";
this.headers = new Headers.Builder();
}
private Builder(Request request) {
this.url = request.url;
this.method = request.method;
this.body = request.body;
this.tag = request.tag;
this.headers = request.headers.newBuilder();
}
public Builder url(HttpUrl url) {
if (url == null) throw new IllegalArgumentException("url == null");
this.url = url;
return this;
}
/**
* Sets the URL target of this request.
*
* @throws IllegalArgumentException if {@code url} is not a valid HTTP or HTTPS URL. Avoid this
* exception by calling {@link HttpUrl#parse}; it returns null for invalid URLs.
*/
public Builder url(String url) {
if (url == null) throw new IllegalArgumentException("url == null");
// Silently replace websocket URLs with HTTP URLs.
if (url.regionMatches(true, 0, "ws:", 0, 3)) {
url = "http:" + url.substring(3);
} else if (url.regionMatches(true, 0, "wss:", 0, 4)) {
url = "https:" + url.substring(4);
}
HttpUrl parsed = HttpUrl.parse(url);
if (parsed == null) throw new IllegalArgumentException("unexpected url: " + url);
return url(parsed);
}
/**
* Sets the URL target of this request.
*
* @throws IllegalArgumentException if the scheme of {@code url} is not {@code http} or {@code
* https}.
*/
public Builder url(URL url) {
if (url == null) throw new IllegalArgumentException("url == null");
HttpUrl parsed = HttpUrl.get(url);
if (parsed == null) throw new IllegalArgumentException("unexpected url: " + url);
return url(parsed);
}
/**
* Sets the header named {@code name} to {@code value}. If this request already has any headers
* with that name, they are all replaced.
*/
public Builder header(String name, String value) {
headers.set(name, value);
return this;
}
/**
* Adds a header with {@code name} and {@code value}. Prefer this method for multiply-valued
* headers like "Cookie".
*
* <p>Note that for some headers including {@code Content-Length} and {@code Content-Encoding},
* OkHttp may replace {@code value} with a header derived from the request body.
*/
public Builder addHeader(String name, String value) {
headers.add(name, value);
return this;
}
public Builder removeHeader(String name) {
headers.removeAll(name);
return this;
}
/** Removes all headers on this builder and adds {@code headers}. */
public Builder headers(Headers headers) {
this.headers = headers.newBuilder();
return this;
}
/**
* Sets this request's {@code Cache-Control} header, replacing any cache control headers already
* present. If {@code cacheControl} doesn't define any directives, this clears this request's
* cache-control headers.
*/
public Builder cacheControl(CacheControl cacheControl) {
String value = cacheControl.toString();
if (value.isEmpty()) return removeHeader("Cache-Control");
return header("Cache-Control", value);
}
public Builder get() {
return method("GET", null);
}
public Builder head() {
return method("HEAD", null);
}
public Builder post(RequestBody body) {
return method("POST", body);
}
public Builder delete(RequestBody body) {
return method("DELETE", body);
}
public Builder delete() {
return delete(RequestBody.create(null, new byte[0]));
}
public Builder put(RequestBody body) {
return method("PUT", body);
}
public Builder patch(RequestBody body) {
return method("PATCH", body);
}
public Builder method(String method, RequestBody body) {
if (method == null || method.length() == 0) {
throw new IllegalArgumentException("method == null || method.length() == 0");
}
if (body != null && !HttpMethod.permitsRequestBody(method)) {
throw new IllegalArgumentException("method " + method + " must not have a request body.");
}
if (body == null && HttpMethod.requiresRequestBody(method)) {
throw new IllegalArgumentException("method " + method + " must have a request body.");
}
this.method = method;
this.body = body;
return this;
}
/**
* Attaches {@code tag} to the request. It can be used later to cancel the request. If the tag
* is unspecified or null, the request is canceled by using the request itself as the tag.
*/
public Builder tag(Object tag) {
this.tag = tag;
return this;
}
public Request build() {
if (url == null) throw new IllegalStateException("url == null");
return new Request(this);
}
}
}
也是用了一個Builder模式，和上面的思想一樣。
創建一個Call對象，因爲最後執行網絡請求的是一個Call對象：
Call call = okHttpClient.newCall(request);
進newCall這個方法去看看：
@Override
public Call newCall(Request request) {
return new RealCall(this, request);
}
我們會發現Call其實是一個接口，RealCall纔是其實現類：
protected RealCall(OkHttpClient client, Request originalRequest) {
this.client = client;
this.originalRequest = originalRequest;
}
異步請求：
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
}
@Override
public void onResponse(Call call, Response response) throws IOException {
String s = response.body().string();
}
});
我們一起來分
@Override
public void enqueue(Callback responseCallback) {
enqueue(responseCallback, false);
}
void enqueue(Callback responseCallback, boolean forWebSocket) {
synchronized (this) {
if (executed) throw new IllegalStateException("Already Executed");
executed = true;
}
client.dispatcher().enqueue(new AsyncCall(responseCallback, forWebSocket));
}
最終執行的是dispatcher(調度器)的enqueue方法：
synchronized void enqueue(AsyncCall call) {
if (runningAsyncCalls.size() < maxRequests && runningCallsForHost(call) < maxRequestsPerHost) {
runningAsyncCalls.add(call);
executorService().execute(call);
} else {
readyAsyncCalls.add(call);
}
}
先來看看runningAsyncCalls等到底是什麼：
/** Ready async calls in the order they'll be run. */
private final Deque<AsyncCall> readyAsyncCalls = new ArrayDeque<>();
/** Running asynchronous calls. Includes canceled calls that haven't finished yet. */
private final Deque<AsyncCall> runningAsyncCalls = new ArrayDeque<>();
/** Running synchronous calls. Includes canceled calls that haven't finished yet. */
private final Deque<RealCall> runningSyncCalls = new ArrayDeque<>();
很明顯，均爲隊列，分別代表準備隊列，正在運行的異步隊列，正在運行的同步隊列。
private int maxRequests = 64;
private int maxRequestsPerHost = 5;
可見，最大的請求數量不能超過64。
那麼上面的代碼就很好理解了，如果正在運行的異步隊列元素數量小於64等條件滿足，call對象可以直接加入隊列，然後由線程池處理call請求，反之加入等待隊列。
public synchronized ExecutorService executorService() {
if (executorService == null) {
executorService = new ThreadPoolExecutor(0, Integer.MAX_VALUE, 60, TimeUnit.SECONDS,
new SynchronousQueue<Runnable>(), Util.threadFactory("OkHttp Dispatcher", false));
}
return executorService;
}
可見executorService()方法是在初始化一個線程池。我們注意到傳入的call是一個AsyncCall，來看看這個類：
final class AsyncCall extends NamedRunnable {
private final Callback responseCallback;
private final boolean forWebSocket;
private AsyncCall(Callback responseCallback, boolean forWebSocket) {
super("OkHttp %s", originalRequest.url().toString());
this.responseCallback = responseCallback;
this.forWebSocket = forWebSocket;
}
String host() {
return originalRequest.url().host();
}
Request request() {
return originalRequest;
}
Object tag() {
return originalRequest.tag();
}
void cancel() {
RealCall.this.cancel();
}
RealCall get() {
return RealCall.this;
}
@Override protected void execute() {
boolean signalledCallback = false;
try {
Response response = getResponseWithInterceptorChain(forWebSocket);
if (canceled) {
signalledCallback = true;
responseCallback.onFailure(RealCall.this, new IOException("Canceled"));
} else {
signalledCallback = true;
responseCallback.onResponse(RealCall.this, response);
}
} catch (IOException e) {
if (signalledCallback) {
// Do not signal the callback twice!
logger.log(Level.INFO, "Callback failure for " + toLoggableString(), e);
} else {
responseCallback.onFailure(RealCall.this, e);
}
} finally {
client.dispatcher().finished(this);
}
}
}
public abstract class NamedRunnable implements Runnable {
protected final String name;
public NamedRunnable(String format, Object... args) {
this.name = String.format(format, args);
}
@Override public final void run() {
String oldName = Thread.currentThread().getName();
Thread.currentThread().setName(name);
try {
execute();
} finally {
Thread.currentThread().setName(oldName);
}
}
protected abstract void execute();
}
public
interface Runnable {
/**
* When an object implementing interface <code>Runnable</code> is used
* to create a thread, starting the thread causes the object's
* <code>run</code> method to be called in that separately executing
* thread.
* <p>
* The general contract of the method <code>run</code> is that it may
* take any action whatsoever.
*
* @see java.lang.Thread#run()
*/
public abstract void run();
}
我們顯然可知，AsyncCall必然實現了run方法，NamedRunnable run裏面又有一個excute方法，我們進AsyncCall的excute裏面看看：
@Override
protected void execute() {
boolean signalledCallback = false;
try {
//攔截器鏈 執行請求
Response response = getResponseWithInterceptorChain(forWebSocket);
if (canceled) {
signalledCallback = true;
responseCallback.onFailure(RealCall.this, new IOException("Canceled"));
} else {
signalledCallback = true;
responseCallback.onResponse(RealCall.this, response);
}
} catch (IOException e) {
if (signalledCallback) {
// Do not signal the callback twice!
logger.log(Level.INFO, "Callback failure for " + toLoggableString(), e);
} else {
responseCallback.onFailure(RealCall.this, e);
}
} finally {
//移除隊列
client.dispatcher().finished(this);
}
}
finally 執行了client.dispatcher().finished(this); 通過調度器移除隊列:
synchronized void finished(AsyncCall call) {
if (!runningAsyncCalls.remove(call)) throw new AssertionError("AsyncCall wasn't running!");
promoteCalls();
}
private void promoteCalls() {
if (runningAsyncCalls.size() >= maxRequests) return; // Already running max capacity.
if (readyAsyncCalls.isEmpty()) return; // No ready calls to promote.
for (Iterator<AsyncCall> i = readyAsyncCalls.iterator(); i.hasNext(); ) {
AsyncCall call = i.next();
if (runningCallsForHost(call) < maxRequestsPerHost) {
i.remove();
runningAsyncCalls.add(call);
executorService().execute(call);
}
if (runningAsyncCalls.size() >= maxRequests) return; // Reached max capacity.
}
}
從上面代碼可以看出，如果一個請求結束後，會從正在運行的異步隊列中remove掉，並且遍歷等待異步隊列，取出call放進正在運行的異步隊列中，然後線程池去執行call。
我們着重來分析一下getResponseWithInterceptorChain這個方法：
private Response getResponseWithInterceptorChain(boolean forWebSocket) throws IOException {
Interceptor.Chain chain = new ApplicationInterceptorChain(0, originalRequest, forWebSocket);
return chain.proceed(originalRequest);
}
class ApplicationInterceptorChain implements Interceptor.Chain {
private final int index;
private final Request request;
private final boolean forWebSocket;
ApplicationInterceptorChain(int index, Request request, boolean forWebSocket) {
this.index = index;
this.request = request;
this.forWebSocket = forWebSocket;
}
@Override public Connection connection() {
return null;
}
@Override public Request request() {
return request;
}
@Override public Response proceed(Request request) throws IOException {
// If there's another interceptor in the chain, call that.
if (index < client.interceptors().size()) {
Interceptor.Chain chain = new ApplicationInterceptorChain(index + 1, request, forWebSocket);
Interceptor interceptor = client.interceptors().get(index);
Response interceptedResponse = interceptor.intercept(chain);
if (interceptedResponse == null) {
throw new NullPointerException("application interceptor " + interceptor
+ " returned null");
}
return interceptedResponse;
}
// No more interceptors. Do HTTP.
return getResponse(request, forWebSocket);
}
}
如果沒有添加攔截器的話，執行getResponse獲取反饋信息。
