OkHttp3用法全解析

1.使用前準備

Android Studio 配置gradle：

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

添加網絡權限：

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

2.異步GET請求

private void getAsynHttp() {
    mOkHttpClient=new OkHttpClient();
    Request.Builder requestBuilder = new Request.Builder().url("http://www.baidu.com");
    //能夠省略，默認是GET請求
    requestBuilder.method("GET",null);
    Request request = requestBuilder.build();
    Call mcall= mOkHttpClient.newCall(request);
    mcall.enqueue(new Callback() {
        @Override
        public void onFailure(Call call, IOException e) {

        }

        @Override
        public 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() {
                @Override
                public void run() {
                    Toast.makeText(getApplicationContext(), "請求成功", Toast.LENGTH_SHORT).show();
                }
            });
        }
    });
}

2.異步POST請求

OkHttp3異步POST請求和OkHttp2.x有一些差異就是沒有FormEncodingBuilder這個類，替代它的是功能更增強大的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() {
            @Override
            public void onFailure(Call call, IOException e) {

            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                String str = response.body().string();
                Log.i("wangshu", str);

                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(getApplicationContext(), "請求成功", Toast.LENGTH_SHORT).show();
                    }
                });
            }

        });
    }

3.異步上傳文件

上傳文件自己也是一個POST請求，上一篇沒有講，這裏咱們補上。首先定義上傳文件類型：

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

將sdcard根目錄的wangshu.txt文件上傳到服務器上：

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() {
            @Override
            public void onFailure(Call call, IOException e) {

            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                Log.i("wangshu",response.body().string());
            }
        });
    }

固然若是想要改成同步的上傳文件只要調用 mOkHttpClient.newCall(request).execute()就能夠了。
在wangshu.txt文件中有一行字「Android網絡編程（六）OkHttp3用法全解析」咱們運行程序點擊發送文件按鈕，最終請求網絡返回的結果就是咱們txt文件中的內容 ：

這裏寫圖片描述

固然不要忘了添加以下權限：

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

4.異步下載文件

下載文件一樣在上一篇沒有講到，實現起來比較簡單，在這裏下載一張圖片，咱們獲得Response後將流寫進咱們指定的圖片文件中就能夠了。

private void downAsynFile() {
    mOkHttpClient = new OkHttpClient();
    String url = "http://img.my.csdn.net/uploads/201603/26/1458988468_5804.jpg";
    Request request = new Request.Builder().url(url).build();
    mOkHttpClient.newCall(request).enqueue(new Callback() {
        @Override
        public void onFailure(Call call, IOException e) {

        }

        @Override
        public 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", "文件下載成功");
       }
   });

}

5.異步上傳Multipart文件

這種場景很經常使用，咱們有時會上傳文件同時還須要傳其餘類型的字段，OkHttp3實現起來很簡單，須要注意的是沒有服務器接收我這個Multipart文件，因此這裏只是舉個例子，具體的應用還要結合實際工做中對應的服務器。
首先定義上傳文件類型：

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() {
       @Override
       public void onFailure(Call call, IOException e) {

       }

       @Override
       public void onResponse(Call call, Response response) throws IOException {
           Log.i("wangshu", response.body().string());
       }
   });
}

6.設置超時時間和緩存

和OkHttp2.x有區別的是不能經過OkHttpClient直接設置超時時間和緩存了，而是經過OkHttpClient.Builder來設置，經過builder配置好OkHttpClient後用builder.build()來返回OkHttpClient，因此咱們一般不會調用new OkHttpClient()來獲得OkHttpClient，而是經過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.關於取消請求和封裝

OkHttpFinal，它目前是基於OkHttp3來進行封裝的。連接描述

8.關於源碼Demo

github源碼下載連接描述