Android(安卓)网络框架学习之OKHttp

OKHTTP

okHttp: OKHttp是Android版Http客户端。非常高效，支持SPDY、连接池、GZIP和 HTTP 缓存。默认情况下，OKHttp会自动处理常见的网络问题，像二次连接、SSL的握手问题。如果你的应用程序中集成了OKHttp，Retrofit默认会使用OKHttp处理其他网络层请求。
An HTTP & SPDY client for Android and Java applications 从Android4.4开始HttpURLConnection的底层实现采用的是okHttp.
使用要求:对于Android：2.3以上，对于Java:java7以上两个模块： okhttp-urlconnection实现.HttpURLConnection API； okhttp-apache实现Apache HttpClient API. 依赖： okio(https://github.com/square/okio):Okio, which OkHttp uses for fast I/O and resizable buffers.

安装：

maven:

<dependency>  <groupId>com.squareup.okhttp</groupId>  <artifactId>okhttp</artifactId>  <version>2.3.0</version></dependency>

Gradle:

compile 'com.squareup.okhttp:okhttp:2.3.0'

GET A URL

同步GET:

  private final OkHttpClient client = new OkHttpClient();  public void run() throws Exception {    Request request = new Request.Builder()        .url("http://publicobject.com/helloworld.txt")        .build();    Response response = client.newCall(request).execute();    if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);    Headers responseHeaders = response.headers();    for (int i = 0; i < responseHeaders.size(); i++) {      System.out.println(responseHeaders.name(i) + ": " + responseHeaders.value(i));    }    System.out.println(response.body().string());  }

异步GET:

在一个工作线程中下载文件，当响应可读时回调Callback接口。读取响应时会阻塞当前线程。OkHttp现阶段不提供异步api来接收响应体。

  private final OkHttpClient client = new OkHttpClient();  public void run() throws Exception {    Request request = new Request.Builder()        .url("http://publicobject.com/helloworld.txt")        .build();    client.newCall(request).enqueue(new Callback() {      @Override public void onFailure(Request request, Throwable throwable) {        throwable.printStackTrace();      }      @Override public void onResponse(Response response) throws IOException {        if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);        Headers responseHeaders = response.headers();        for (int i = 0; i < responseHeaders.size(); i++) {          System.out.println(responseHeaders.name(i) + ": " + responseHeaders.value(i));        }        System.out.println(response.body().string());      }    });  }

访问Header:

  private final OkHttpClient client = new OkHttpClient();  public void run() throws Exception {    Request request = new Request.Builder()        .url("https://api.github.com/repos/square/okhttp/issues")        .header("User-Agent", "OkHttp Headers.java")        .addHeader("Accept", "application/json; q=0.5")        .addHeader("Accept", "application/vnd.github.v3+json")        .build();    Response response = client.newCall(request).execute();    if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);    System.out.println("Server: " + response.header("Server"));    System.out.println("Date: " + response.header("Date"));    System.out.println("Vary: " + response.headers("Vary"));  }

POST TO A SERVER

Posting a String:

public static final MediaType jsonReq    = MediaType.parse("application/json; charset=utf-8");OkHttpClient client = new OkHttpClient();String post(String url, String json) throws IOException {  RequestBody body = RequestBody.create(jsonReq, json);  Request request = new Request.Builder()      .url(url)      .post(body)      .build();  Response response = client.newCall(request).execute();  return response.body().string();}

Posting Streaming:

 public static final MediaType MEDIA_TYPE_MARKDOWN      = MediaType.parse("text/x-markdown; charset=utf-8");  private final OkHttpClient client = new OkHttpClient();  public void run() throws Exception {    RequestBody requestBody = new RequestBody() {      @Override public MediaType contentType() {        return MEDIA_TYPE_MARKDOWN;      }      @Override public void writeTo(BufferedSink sink) throws IOException {        sink.writeUtf8("Numbers\n");        sink.writeUtf8("-------\n");        for (int i = 2; i <= 997; i++) {          sink.writeUtf8(String.format(" * %s = %s\n", i, factor(i)));        }      }      private String factor(int n) {        for (int i = 2; i < n; i++) {          int x = n / i;          if (x * i == n) return factor(x) + " × " + i;        }        return Integer.toString(n);      }    };    Request request = new Request.Builder()        .url("https://api.github.com/markdown/raw")        .post(requestBody)        .build();    Response response = client.newCall(request).execute();    if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);    System.out.println(response.body().string());  }

Posting a File:

 public static final MediaType MEDIA_TYPE_MARKDOWN      = MediaType.parse("text/x-markdown; charset=utf-8");  private final OkHttpClient client = new OkHttpClient();  public void run() throws Exception {    File file = new File("README.md");    Request request = new Request.Builder()        .url("https://api.github.com/markdown/raw")        .post(RequestBody.create(MEDIA_TYPE_MARKDOWN, file))        .build();    Response response = client.newCall(request).execute();    if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);    System.out.println(response.body().string());  }

Posting from parameters:

private final OkHttpClient client = new OkHttpClient();  public void run() throws Exception {    RequestBody formBody = new FormEncodingBuilder()        .add("search", "Jurassic Park")        .build();    Request request = new Request.Builder()        .url("https://en.wikipedia.org/w/index.php")        .post(formBody)        .build();    Response response = client.newCall(request).execute();    if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);    System.out.println(response.body().string());  }

Posting a multipart request:

 private static final String IMGUR_CLIENT_ID = "...";  private static final MediaType MEDIA_TYPE_PNG = MediaType.parse("image/png");  private final OkHttpClient client = new OkHttpClient();  public void run() throws Exception {    // Use the imgur image upload API as documented at https://api.imgur.com/endpoints/image    RequestBody requestBody = new MultipartBuilder()        .type(MultipartBuilder.FORM)        .addPart(            Headers.of("Content-Disposition", "form-data; name=\"title\""),            RequestBody.create(null, "Square Logo"))        .addPart(            Headers.of("Content-Disposition", "form-data; name=\"image\""),            RequestBody.create(MEDIA_TYPE_PNG, new File("website/static/logo-square.png")))        .build();    Request request = new Request.Builder()        .header("Authorization", "Client-ID " + IMGUR_CLIENT_ID)        .url("https://api.imgur.com/3/image")        .post(requestBody)        .build();    Response response = client.newCall(request).execute();    if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);    System.out.println(response.body().string());  }

Posing Json with Gson

 private final OkHttpClient client = new OkHttpClient();  private final Gson gson = new Gson();  public void run() throws Exception {    Request request = new Request.Builder()        .url("https://api.github.com/gists/c2a7c39532239ff261be")        .build();    Response response = client.newCall(request).execute();    if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);    Gist gist = gson.fromJson(response.body().charStream(), Gist.class);    for (Map.Entry<String, GistFile> entry : gist.files.entrySet()) {      System.out.println(entry.getKey());      System.out.println(entry.getValue().content);    }  }  static class Gist {    Map<String, GistFile> files;  }  static class GistFile {    String content;  }

Response Caching：

为了缓存响应，你需要一个你可以读写的缓存目录，和缓存大小的限制。这个缓存目录应该是私有的，不信任的程序应不能读取缓存内容。
一个缓存目录同时拥有多个缓存访问是错误的。大多数程序只需要调用一次 new OkHttp() ，在第一次调用时配置好缓存，然后其他地方只需要调用这个实例就可以了。否则两个缓存示例互相干扰，破坏响应缓存，而且有可能会导致程序崩溃。
响应缓存使用HTTP头作为配置。你可以在请求头中添加 Cache-Control: max-stale=3600 ,OkHttp缓存会支持。你的服务通过响应头确定响应缓存多长时间，例如使用 Cache-Control: max-age=9600 。

private final OkHttpClient client;  public CacheResponse(File cacheDirectory) throws Exception {    int cacheSize = 10 * 1024 * 1024; // 10 MiB    Cache cache = new Cache(cacheDirectory, cacheSize);    client = new OkHttpClient();    client.setCache(cache);  }  public void run() throws Exception {    Request request = new Request.Builder()        .url("http://publicobject.com/helloworld.txt")        .build();    Response response1 = client.newCall(request).execute();    if (!response1.isSuccessful()) throw new IOException("Unexpected code " + response1);    String response1Body = response1.body().string();    System.out.println("Response 1 response:          " + response1);    System.out.println("Response 1 cache response:    " + response1.cacheResponse());    System.out.println("Response 1 network response:  " + response1.networkResponse());  }

Canceling a Call

    final Call call = client.newCall(request);        call.cancel();

Timeouts:

private final OkHttpClient client;  public ConfigureTimeouts() throws Exception {    client = new OkHttpClient();    client.setConnectTimeout(10, TimeUnit.SECONDS);    client.setWriteTimeout(10, TimeUnit.SECONDS);    client.setReadTimeout(30, TimeUnit.SECONDS);  }

Handling Authentication:

private final OkHttpClient client = new OkHttpClient();  public void run() throws Exception {    client.setAuthenticator(new Authenticator() {      @Override public Request authenticate(Proxy proxy, Response response) {        System.out.println("Authenticating for response: " + response);        System.out.println("Challenges: " + response.challenges());        String credential = Credentials.basic("jesse", "password1");        return response.request().newBuilder()            .header("Authorization", credential)            .build();      }      @Override public Request authenticateProxy(Proxy proxy, Response response) {        return null; // Null indicates no attempt to authenticate.      }    });    Request request = new Request.Builder()        .url("http://publicobject.com/secrets/hellosecret.txt")        .build();    Response response = client.newCall(request).execute();    if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);    System.out.println(response.body().string());  }

为避免当验证失败时多次重试，我们可以通过返回null来放弃验证：

 if (responseCount(response) >= 3) {    return null; // If we've failed 3 times, give up.  }//添加以下方法private int responseCount(Response response) {    int result = 1;    while ((response = response.priorResponse()) != null) {      result++;    }    return result;  }

Interceptors

class LoggingInterceptor implements Interceptor {  @Override public Response intercept(Chain chain) throws IOException {    Request request = chain.request();    long t1 = System.nanoTime();    logger.info(String.format("Sending request %s on %s%n%s",        request.url(), chain.connection(), request.headers()));    Response response = chain.proceed(request);    long t2 = System.nanoTime();    logger.info(String.format("Received response for %s in %.1fms%n%s",        response.request().url(), (t2 - t1) / 1e6d, response.headers()));    return response;  }}

Application Interceptors：

OkHttpClient client = new OkHttpClient();client.interceptors().add(new LoggingInterceptor());

Network Interceptors

OkHttpClient client = new OkHttpClient();client.networkInterceptors().add(new LoggingInterceptor());