導(dǎo)圖

OkHttp源碼分析.png

簡介

OkHttp是Square公司開源的一款面向Java和Android平臺的HTTP客戶端，是目前最主流的網(wǎng)絡(luò)框架之一。在Android4.4中，HttpUrlConnection底層已經(jīng)默認使用okhttp實現(xiàn)。

特點

• 支持HTTP2/SPDY黑科技
• socket自動選擇最好路線，并支持自動重連
• 擁有自動維護的socket連接池，減少握手次數(shù)
• 擁有隊列線程池，輕松寫并發(fā)
• 擁有Interceptors輕松處理請求與響應(yīng)（比如透明GZIP壓縮,LOGGING）
• 基于Headers的緩存策略

基本用法

創(chuàng)建OkHttpClient對象

OkHttpClient為OkHttp初始的配置中心，通過它可以完成初始參數(shù)的配置，設(shè)置超時時間，添加自定義攔截器，初始化線程池，代理等工作

public OkHttpClient() {
    this(new Builder());
  }
  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;
      this.certificateChainCleaner = builder.certificateChainCleaner;
    } else {
      X509TrustManager trustManager = systemDefaultTrustManager();
      this.sslSocketFactory = systemDefaultSslSocketFactory(trustManager);
      this.certificateChainCleaner = CertificateChainCleaner.get(trustManager);
    }
    this.hostnameVerifier = builder.hostnameVerifier;
    this.certificatePinner = builder.certificatePinner.withCertificateChainCleaner(
        certificateChainCleaner);
    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;
    this.pingInterval = builder.pingInterval;
  }

兩種創(chuàng)建方式

• 默認創(chuàng)建。直接new OkHttpClient，將使用Okhttp的默認配置
• 自定義創(chuàng)建。通過指定一個Builder

創(chuàng)建Request對象

Request用于描述一個HTTP請求，比如請求的方法是"GET"還是"POST"，請求的URL，請求的header，請求的body，請求的緩存策略等

//創(chuàng)建一個Request
Request request = new Request.Builder()
        .url(url)
        .build();

創(chuàng)建Call對象

Call是一次HTTP請求的Task，它會執(zhí)行網(wǎng)絡(luò)請求以獲得響應(yīng)。OkHttp中的網(wǎng)絡(luò)請求執(zhí)行Call既可以同步進行，也可以異步進行。調(diào)用call.execute()將直接執(zhí)行網(wǎng)絡(luò)請求，阻塞直到獲得響應(yīng)。而調(diào)用call.enqueue()傳入回調(diào)，則會將Call放入一個異步執(zhí)行隊列，由ExecutorService在后臺執(zhí)行。

//new call
Call call = mOkHttpClient.newCall(request); 

執(zhí)行網(wǎng)絡(luò)請求并獲取響應(yīng)

同步請求

同步請求會對當(dāng)前線程產(chǎn)生阻塞，直到請求響應(yīng)返回

Response response = client.newCall(request).execute();

異步請求

異步請求將提交到線程池中執(zhí)行

call.enqueue(new Callback(){
    @Override
    public void onResponse(final Response response) throws IOException{
           //String htmlStr =  response.body().string();
    }

    @Override
    public void onFailure(Request request, IOException e) {

    }
});

更多用法請參考 http://www.cnblogs.com/ct2011/p/3997368.html