1.使用前准备

Android Studio 配置gradle：

 compile 'com.squareup.okhttp3:okhttp:3.2.0'compile 'com.squareup.okio:okio:1.7.0'

添加网络权限：

<uses-permission android:name="android.permission.INTERNET"/>

2.异步GET请求

    private void getAsynHttp() {mOkHttpClient=new OkHttpClient();Request.Builder requestBuilder = new Request.Builder().url("http://www.baidu.com");//可以省略，默认是GET请求requestBuilder.method("GET",null);Request request = requestBuilder.build();Call mcall= mOkHttpClient.newCall(request);mcall.enqueue(new Callback() {@Overridepublic void onFailure(Call call, IOException e) {}@Overridepublic void onResponse(Call call, Response response) throws IOException {if (null != response.cacheResponse()) {String str = response.cacheResponse().toString();Log.i("wangshu", "cache---" + str);} else {response.body().string();String str = response.networkResponse().toString();Log.i("wangshu", "network---" + str);}runOnUiThread(new Runnable() {@Overridepublic void run() {Toast.makeText(getApplicationContext(), "请求成功", Toast.LENGTH_SHORT).show();}});}});
}

2.异步POST请求

OkHttp3异步POST请求和OkHttp2.x有一些差别就是没有FormEncodingBuilder这个类，替代它的是功能更加强大的FormBody：

  private void postAsynHttp() {mOkHttpClient=new OkHttpClient();RequestBody formBody = new FormBody.Builder().add("size", "10").build();Request request = new Request.Builder().url("http://api.1-blog.com/biz/bizserver/article/list.do").post(formBody).build();Call call = mOkHttpClient.newCall(request);call.enqueue(new Callback() {@Overridepublic void onFailure(Call call, IOException e) {}@Overridepublic void onResponse(Call call, Response response) throws IOException {String str = response.body().string();Log.i("wangshu", str);runOnUiThread(new Runnable() {@Overridepublic void run() {Toast.makeText(getApplicationContext(), "请求成功", Toast.LENGTH_SHORT).show();}});}});}

3.异步上传文件

上传文件本身也是一个POST请求，上一篇没有讲，这里我们补上。首先定义上传文件类型：

public static final MediaType MEDIA_TYPE_MARKDOWN= MediaType.parse("text/x-markdown; charset=utf-8");

将sdcard根目录的wangshu.txt文件上传到服务器上：

private void postAsynFile() {mOkHttpClient=new OkHttpClient();File file = new File("/sdcard/wangshu.txt");Request request = new Request.Builder().url("https://api.github.com/markdown/raw").post(RequestBody.create(MEDIA_TYPE_MARKDOWN, file)).build();mOkHttpClient.newCall(request).enqueue(new Callback() {@Overridepublic void onFailure(Call call, IOException e) {}@Overridepublic void onResponse(Call call, Response response) throws IOException {Log.i("wangshu",response.body().string());}});}

当然如果想要改为同步的上传文件只要调用 mOkHttpClient.newCall(request).execute()就可以了。
在wangshu.txt文件中有一行字“Android网络编程（六）OkHttp3用法全解析”我们运行程序点击发送文件按钮，最终请求网络返回的结果就是我们txt文件中的内容 ：

这里写图片描述

当然不要忘了添加如下权限：

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

4.异步下载文件

下载文件同样在上一篇没有讲到，实现起来比较简单，在这里下载一张图片，我们得到Response后将流写进我们指定的图片文件中就可以了。

private void downAsynFile() {mOkHttpClient = new OkHttpClient();String url = "https://img-my.csdn.net/uploads/201603/26/1458988468_5804.jpg";Request request = new Request.Builder().url(url).build();mOkHttpClient.newCall(request).enqueue(new Callback() {@Overridepublic void onFailure(Call call, IOException e) {}@Overridepublic void onResponse(Call call, Response response) {InputStream inputStream = response.body().byteStream();FileOutputStream fileOutputStream = null;try {fileOutputStream = new FileOutputStream(new File("/sdcard/wangshu.jpg"));byte[] buffer = new byte[2048];int len = 0;while ((len = inputStream.read(buffer)) != -1) {fileOutputStream.write(buffer, 0, len);}fileOutputStream.flush();} catch (IOException e) {Log.i("wangshu", "IOException");e.printStackTrace();}Log.d("wangshu", "文件下载成功");}});

}

5.异步上传Multipart文件

这种场景很常用，我们有时会上传文件同时还需要传其他类型的字段，OkHttp3实现起来很简单，需要注意的是没有服务器接收我这个Multipart文件，所以这里只是举个例子，具体的应用还要结合实际工作中对应的服务器。
首先定义上传文件类型：

   private static final MediaType MEDIA_TYPE_PNG = MediaType.parse("image/png");private void sendMultipart(){mOkHttpClient = new OkHttpClient();RequestBody requestBody = new MultipartBody.Builder().setType(MultipartBody.FORM).addFormDataPart("title", "wangshu").addFormDataPart("image", "wangshu.jpg",RequestBody.create(MEDIA_TYPE_PNG, new File("/sdcard/wangshu.jpg"))).build();Request request = new Request.Builder().header("Authorization", "Client-ID " + "...").url("https://api.imgur.com/3/image").post(requestBody).build();mOkHttpClient.newCall(request).enqueue(new Callback() {@Overridepublic void onFailure(Call call, IOException e) {}@Overridepublic void onResponse(Call call, Response response) throws IOException {Log.i("wangshu", response.body().string());}});
}

6.设置超时时间和缓存

和OkHttp2.x有区别的是不能通过OkHttpClient直接设置超时时间和缓存了，而是通过OkHttpClient.Builder来设置，通过builder配置好OkHttpClient后用builder.build()来返回OkHttpClient，所以我们通常不会调用new OkHttpClient()来得到OkHttpClient，而是通过builder.build()：

    File sdcache = getExternalCacheDir();int cacheSize = 10 * 1024 * 1024;OkHttpClient.Builder builder = new OkHttpClient.Builder().connectTimeout(15, TimeUnit.SECONDS).writeTimeout(20, TimeUnit.SECONDS).readTimeout(20, TimeUnit.SECONDS).cache(new Cache(sdcache.getAbsoluteFile(), cacheSize));OkHttpClient mOkHttpClient=builder.build();

7.关于取消请求和封装

OkHttpFinal，它目前是基于OkHttp3来进行封装的。链接描述

8.关于源码Demo

github源码下载链接描述