导图
OkHttp源码分析.png
简介
OkHttp是Square公司开源的一款面向Java和Android平台的HTTP客户端，是目前最主流的网络框架之一。在Android4.4中，HttpUrlConnection底层已经默认使用okhttp实现。
特点
- 支持HTTP2/SPDY黑科技
- socket自动选择最好路线，并支持自动重连
- 拥有自动维护的socket连接池，减少握手次数
- 拥有队列线程池，轻松写并发
- 拥有Interceptors轻松处理请求与响应（比如透明GZIP压缩,LOGGING）
- 基于Headers的缓存策略
基本用法
创建OkHttpClient对象
OkHttpClient为OkHttp初始的配置中心，通过它可以完成初始参数的配置，设置超时时间，添加自定义拦截器，初始化线程池，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;
}
两种创建方式
- 默认创建。直接new OkHttpClient，将使用Okhttp的默认配置
- 自定义创建。通过指定一个Builder
创建Request对象
Request用于描述一个HTTP请求，比如请求的方法是"GET"还是"POST"，请求的URL，请求的header，请求的body，请求的缓存策略等
//创建一个Request
Request request = new Request.Builder()
.url(url)
.build();
创建Call对象
Call是一次HTTP请求的Task，它会执行网络请求以获得响应。OkHttp中的网络请求执行Call既可以同步进行，也可以异步进行。调用call.execute()将直接执行网络请求，阻塞直到获得响应。而调用call.enqueue()传入回调，则会将Call放入一个异步执行队列，由ExecutorService在后台执行。
//new call
Call call = mOkHttpClient.newCall(request);
执行网络请求并获取响应
同步请求
同步请求会对当前线程产生阻塞，直到请求响应返回
Response response = client.newCall(request).execute();
异步请求
异步请求将提交到线程池中执行
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) {
}
});
