- OkHttp 使用。
- 創(chuàng)建OkHttpClient 對(duì)象。
- build Request 對(duì)象，注入Call對(duì)象，new 出Call對(duì)象。
- 調(diào)用execute（同步）或者 enqueue（異步）發(fā)送請(qǐng)求
package com.example.myapplication;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
public class TestOkHttp {
static OkHttpClient okHttpClient = new OkHttpClient.Builder()
.readTimeout(5, TimeUnit.MINUTES).build();
//同步
public static void synRequest(){
Request request = new Request.Builder().url("http://www.baidu.com").get().build();
Call call = okHttpClient.newCall(request);
try {
Response response = call.execute();
System.out.println(response.body().string());
} catch (IOException e) {
e.printStackTrace();
}
}
//異步
public static void AsynRequest(){
Request request = new Request.Builder().url("http://www.baidu.com").get().build();
Call call = okHttpClient.newCall(request);
Callback callback = new Callback() {
@Override
public void onFailure(Call call, IOException e) {
}
@Override
public void onResponse(Call call, Response response) throws IOException {
System.out.println(response.body().string());
}
};
call.enqueue(callback);
}
public static void main(String[] args) {
synRequest();
AsynRequest();
}
}
簡(jiǎn)圖
- OkHttp源碼分析。
image.png
- Dispatcher 分發(fā)器
用于維護(hù)請(qǐng)求的狀態(tài)，并維護(hù)一個(gè)線程池，執(zhí)行請(qǐng)求。
/** Executes calls. Created lazily. */
/** 線程池 */
private @Nullable ExecutorService executorService;
/** Ready async calls in the order they'll be run. */
/** 準(zhǔn)備就緒的請(qǐng)求隊(duì)列 */
private final Deque<AsyncCall> readyAsyncCalls = new ArrayDeque<>();
/** Running asynchronous calls. Includes canceled calls that haven't finished yet. */
/** (異步)正在執(zhí)行的請(qǐng)求隊(duì)列 ，并包含了已經(jīng)執(zhí)行，被取消的請(qǐng)求*/
private final Deque<AsyncCall> runningAsyncCalls = new ArrayDeque<>();
/** Running synchronous calls. Includes canceled calls that haven't finished yet. */
/** (同步)正在執(zhí)行的請(qǐng)求隊(duì)列 ，并包含了已經(jīng)執(zhí)行，被取消的請(qǐng)求*/
private final Deque<RealCall> runningSyncCalls = new ArrayDeque<>();
- 異步請(qǐng)求任務(wù)調(diào)度
private boolean promoteAndExecute() {
assert (!Thread.holdsLock(this));
List<AsyncCall> executableCalls = new ArrayList<>();
boolean isRunning;
synchronized (this) {
//遍歷就緒請(qǐng)求隊(duì)列
for (Iterator<AsyncCall> i = readyAsyncCalls.iterator(); i.hasNext(); ) {
AsyncCall asyncCall = i.next();
//判斷不能大于請(qǐng)求最大值
if (runningAsyncCalls.size() >= maxRequests) break; // Max capacity.
//判斷執(zhí)行線程不行超過(guò)最大線程數(shù)
if (asyncCall.callsPerHost().get() >= maxRequestsPerHost) continue; // Host max capacity.
//從就緒隊(duì)列移除
i.remove();
//請(qǐng)求線程計(jì)數(shù)+1
asyncCall.callsPerHost().incrementAndGet();
//添加到線程池執(zhí)行隊(duì)列
executableCalls.add(asyncCall);
//添加到正在執(zhí)行的異步隊(duì)列
runningAsyncCalls.add(asyncCall);
}
isRunning = runningCallsCount() > 0;
}
//遍歷執(zhí)行請(qǐng)求
for (int i = 0, size = executableCalls.size(); i < size; i++) {
AsyncCall asyncCall = executableCalls.get(i);
asyncCall.executeOn(executorService());
}
return isRunning;
}
- interceptor 攔截器
image.png
image.png
執(zhí)行請(qǐng)求最主要的是攔截器鏈，通過(guò)和攔截器方法
形成遞歸調(diào)用（chain.proceed這個(gè)被攔截器調(diào)用的代碼我就不貼了）
Response getResponseWithInterceptorChain() throws IOException {
// Build a full stack of interceptors.
List<Interceptor> interceptors = new ArrayList<>();
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) {
interceptors.addAll(client.networkInterceptors());
}
interceptors.add(new CallServerInterceptor(forWebSocket));
Interceptor.Chain chain = new RealInterceptorChain(interceptors, transmitter, null, 0,
originalRequest, this, client.connectTimeoutMillis(),
client.readTimeoutMillis(), client.writeTimeoutMillis());
boolean calledNoMoreExchanges = false;
try {
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);
}
}
}
public Response proceed(Request request, Transmitter transmitter, @Nullable Exchange exchange)
throws IOException {
if (index >= interceptors.size()) throw new AssertionError();
calls++;
// If we already have a stream, confirm that the incoming request will use it.
if (this.exchange != null && !this.exchange.connection().supportsUrl(request.url())) {
throw new IllegalStateException("network interceptor " + interceptors.get(index - 1)
+ " must retain the same host and port");
}
// If we already have a stream, confirm that this is the only call to chain.proceed().
if (this.exchange != null && calls > 1) {
throw new IllegalStateException("network interceptor " + interceptors.get(index - 1)
+ " must call proceed() exactly once");
}
// Call the next interceptor in the chain.
RealInterceptorChain next = new RealInterceptorChain(interceptors, transmitter, exchange,
index + 1, request, call, connectTimeout, readTimeout, writeTimeout);
Interceptor interceptor = interceptors.get(index);
Response response = interceptor.intercept(next);
// Confirm that the next interceptor made its required call to chain.proceed().
if (exchange != null && index + 1 < interceptors.size() && next.calls != 1) {
throw new IllegalStateException("network interceptor " + interceptor
+ " must call proceed() exactly once");
}
// Confirm that the intercepted response isn't null.
if (response == null) {
throw new NullPointerException("interceptor " + interceptor + " returned null");
}
if (response.body() == null) {
throw new IllegalStateException(
"interceptor " + interceptor + " returned a response with no body");
}
return response;
}
- RetryAndFollowUpInterceptor.png
- BridgeInterceptor.png
- 緩存攔截器，主要是采用
，用get方法，key的md5。
緩存策略：
- 緩存中沒有Response、不使用緩存、https沒有成功握手，hasConditions、!isCacheable；cacheResponse=null，重新請(qǐng)求。
- 其余的符合條件在head中打上標(biāo)記返回緩存。
- ConnectInterceptor.png
- ConnectInterceptor.png
6.根據(jù)的數(shù)量啟動(dòng)清理連接池，采用的GC的標(biāo)記-清除算法--
image.png
-
主要看下面代碼
執(zhí)行請(qǐng)求
@Override public Response intercept(Chain chain) throws IOException {
RealInterceptorChain realChain = (RealInterceptorChain) chain;
Exchange exchange = realChain.exchange();
Request request = realChain.request();
long sentRequestMillis = System.currentTimeMillis();
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);
}
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) {
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 {
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;
}
}
