android OkHttp3.0
OkHttp是一个高效的HTTP库: 1.支持 SPDY ，共享同一个Socket来处理同一个服务器的所有请求 2.如果SPDY不可用，则通过连接池来减少请求延时 3.无缝的支持GZIP来减少数据流量 4.缓存响应数据来减少重复的网络请求 优点： OkHttp会从很多常用的连接问题中自动恢复。如果您的服务器配置了多个IP地址，当第一个IP连接失败的时候，会自动尝试下一个IP。OkHttp还处理了代理服务器问题和SSL握手失败问题。 使用 OkHttp 无需重写您程序中的网络代码。OkHttp实现了几乎和java.net.HttpURLConnection一样的API。如果您用了 Apache HttpClient，则OkHttp也提供了一个对应的okhttp-apache 模块 Okhttp的基本使用，从以下五方面讲解：
1、Get请求(同步和异步) 2、POST请求表单(key-value) 3、POST请求提交(JSON/String/文件等)（这个有待研究） 4、文件下载 5、请求超时设置
添加库依赖 compile 'com.squareup.okhttp3:okhttp:3.4.1' compile 'com.github.franmontiel:PersistentCookieJar:v0.9.3' // Cookies持久化库 compile 'com.squareup.okhttp3:logging-interceptor:3.4.1' 1、GET //同步GET请求 OkHttpClient client = new OkHttpClient(); String run(String url) throws IOException { Request request = new Request.Builder().url(url).build(); Response response = client.newCall(request).execute(); return response.body().string(); } //异步GET请求 OkHttpClient client=new OkHttpClient(); Request request = new Request.Builder().url(url).build(); client.newCall(request).enqueue(new Callback() { @Override public void onFailure(Request request, IOException e) {} @Override public void onResponse(Response response) throws IOException {} }); 2、POST public static final MediaType JSON = MediaType.parse("application/json; charset=utf-8"); OkHttpClient client = new OkHttpClient(); String post(String url, String json) throws IOException { RequestBody body = RequestBody.create(JSON, json); Request request = new Request.Builder() .url(url) .post(body) .build(); Response response = client.newCall(request).execute(); return response.body().string(); } 3、异步调用 使用enqueue方法，将call放入请求队列，然后okHttp会在线程池中进行网络访问 OkHttpClient client = new OkHttpClient(); Request request = new Request.Builder().url("https://github.com").build(); client.newCall(request).enqueue(new Callback() { @Override public void onFailure(Call call, IOException e) { } @Override public void onResponse(Call call, Response response) throws IOException { Log.d("onResponse", "response.body(): "+response.body().string()); } }); 4、HTTP头部的设置和读取 HTTP 头的数据结构是 Map<String, List<String>> 类型。对于每个HTTP头，可能有多个值。但是大部分HTTP头都只有一个值，只有少部分HTTP头允许多个值。OkHttp的处理方式是： Request: header(name,value) 来设置HTTP头的唯一值 addHeader(name,value) 来补充新值 Response: header(name) 读取唯一值或多个值的最后一个值 headers(name) 获取所有值 // OkHttpClient client = new OkHttpClient(); Request request = new Request.Builder() .url("https://github.com") .header("User-Agent", "super agent") .addHeader("Accept", "text/html") .build(); Response response = client.newCall(request).execute(); if (!response.isSuccessful()) { throw new IOException("error: " + response); } System.out.println(response.header("Server")); System.out.println(response.headers("Set-Cookie")); 5、表单提交 RequestBody formBody = new FormEncodingBuilder() .add("query", "Hello") .build(); 6、文件上传 指定 MultipartBuilder.FORM 类型并通过addPart方法添加不同的Part（每个Part由Header和RequestBody两部分组成），最后调用builde()方法构建一个RequestBody。 MediaType MEDIA_TYPE_TEXT = MediaType.parse("text/plain"); RequestBody requestBody = new MultipartBuilder() .type(MultipartBuilder.FORM) .addPart( Headers.of("Content-Disposition", "form-data; name=\"title\""), RequestBody.create(null, "input txt")) .addPart( Headers.of("Content-Disposition", "form-data; name=\"file\""), RequestBody.create(MEDIA_TYPE_TEXT, new File("input.txt"))) .build(); 7、使用流的方式发送POST请求 OkHttpClient client = new OkHttpClient(); final MediaType MEDIA_TYPE_TEXT = MediaType.parse("text/plain"); final String postBody = "Hello World"; RequestBody requestBody = new RequestBody() { @Override public MediaType contentType() { return MEDIA_TYPE_TEXT; } @Override public void writeTo(BufferedSink sink) throws IOException { sink.writeUtf8(postBody); } @Override public long contentLength() throws IOException { return postBody.length(); } }; Request request = new Request.Builder() .url("http://www.baidu.com") .post(requestBody) .build(); Response response = client.newCall(request).execute(); if (!response.isSuccessful()) { throw new IOException("eror: " + response); } System.out.println(response.body().string()); 8、缓存控制CacheControl Request request = new Request.Builder() .cacheControl(new CacheControl.Builder().noCache().build()) // 强制不缓存 .url("http://publicobject.com/helloworld.txt") .build(); Request request = new Request.Builder() .cacheControl(new CacheControl.Builder().maxAge(0, TimeUnit.SECONDS).build()) // 缓存策略由服务器指定 .url("http://publicobject.com/helloworld.txt") .build(); Request request = new Request.Builder() .cacheControl(new CacheControl.Builder().onlyIfCached().build()) //强制缓存 .url("http://publicobject.com/helloworld.txt") .build(); Response forceCacheResponse = client.newCall(request).execute(); if (forceCacheResponse.code() != 504) { // The resource was cached! Show it. } else { // The resource was not cached. } Request request = new Request.Builder() .cacheControl(new CacheControl.Builder().maxStale(365, TimeUnit.DAYS).build()) // 允许使用旧的缓存 .url("http://publicobject.com/helloworld.txt") .build(); 9、拦截器：可以监视，重写（重写请求、重写响应）和重试 拦截器可以注册为应用拦截器和网络拦截器 应用拦截器： 不需要关心像重定向和重试这样的中间响应 总是调用一次，即使HTTP响应从缓存中获取服务 监视应用原始意图。不关心OkHttp注入的像If-None-Match头 允许短路并不调用Chain.proceed() 允许重试并执行多个Chain.proceed()调用 网络拦截器： 可以操作像重定向和重试这样的中间响应 对于短路网络的缓存响应不会调用 监视即将要通过网络传输的数据 访问运输请求的Connection 重写请求 //重写响应 private static final Interceptor interceptor = new Interceptor() { @Override public Response intercept(Interceptor.Chain chain) throws IOException { Response originalResponse = chain.proceed(chain.request()); return originalResponse.newBuilder() .header("Cache-Control", "max-age=60") .build(); } }; OkHttpClient client = new OkHttpClient.Builder() .addInterceptor(new HttpLoggingInterceptor() // 应用拦截器 .addNetworkInterceptor(interceptor) // 网络拦截器 .setLevel(HttpLoggingInterceptor.Level.BODY)) .build(); 10、缓存设置 File cacheDirectory = new File(getApplicationContext().getCacheDir().getAbsolutePath(), "Cache"); Cache cache = new Cache(cacheDirectory, 10 * 1024 * 1024)); // 创建缓存类 OkHttpClient client = new OkHttpClient.Builder() .retryOnConnectionFailure(true) .connectTimeout(15, TimeUnit.SECONDS) // 连接超时设置 .readTimeout(10,TimeUnit.SECONDS); // 读超时设置 .writeTimeout(10,TimeUnit.SECONDS); // 写超时设置 .cache(cache) // 设置缓存，okhttp默认是没有缓存,且没有缓存目录的 .build(); 9、Cookies缓存：由CookieJar统一管理Cookies，只需要对OkHttpClient的cookieJar进行设置即可 OkHttpClient mHttpClient = new OkHttpClient.Builder().cookieJar(new CookieJar() { private final HashMap<String, List<Cookie>> cookieStore = new HashMap<>(); @Override public void saveFromResponse(HttpUrl url, List<Cookie> cookies) { cookieStore.put(url.host(), cookies); } @Override public List<Cookie> loadForRequest(HttpUrl url) { List<Cookie> cookies = cookieStore.get(url.host()); return cookies != null ? cookies : new ArrayList<Cookie>(); } }).build(); 10、Cookies持久化：PersistentCookieJar ClearableCookieJar cookieJar = new PersistentCookieJar(new SetCookieCache(), new SharedPrefsCookiePersistor(context)); OkHttpClient okHttpClient = new OkHttpClient.Builder() .cookieJar(cookieJar) .build();