OkHttp网络框架的使用

    本文主要整理下关于OkHttp3的一些使用。通过OkHttp框架去请求网络数据，一般包括下面几个步骤：

            1. 创建OkHttpClient 对象

            2. 创建Request对象（对于get和post请求来说，在创建Request对象时略有不同）

            3. 创建Call对象

            4. 开始请求，返回Response对象

            5. 在Response对象中，获取对应的数据

   下面主要列举下如下几种使用情景：

        1.同步get请求

        2.异步get请求

        3.post请求上传键值对

        4.post请求上传json串

        5.post请求上传文件

        6.get请求下载文件

   下面会一一列举这六种情况下代码实现。

1.同步get请求

 需要说下，关于同步请求的话，不能在UI线程中直接执行，必须放到子线程中去做对应网络请求

/**     * 同步get请求     */    private void executeNet(){        //1.创建OkHttpClient对象        OkHttpClient mOkHttpClient = new OkHttpClient();        //2.创建Request对象        Request request = new Request.Builder()                .url(URL)                .build();        //3.创建Call对象        Call call=mOkHttpClient.newCall(request);        //4.开始同步请求，返回Response对象        try {            Response mResponse = call.execute();            String result=mResponse.body().string();            Log.i(TAG, "服务器返回结果(同步请求)：  " + result);            Bundle mBundle=new Bundle();            mBundle.putString("result",result);            Message msg=new Message();            msg.setData(mBundle);            msg.what=1;            mHandler.sendMessage(msg);        } catch (IOException e) {            e.printStackTrace();        }    }

2.异步get请求

  异步请求，可以直接在UI线程中去执行，但是回调的onResponse()方法并不是UI线程，所以不能在onResponse方法中直接去操作控件

/**     * 异步get请求     */    private void enqueueNet(){        OkHttpClient mOkHttpClient = new OkHttpClient();        final Request request = new Request.Builder()                .url(URL)                .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 {                //需要注意，response.body().string()调用一次后，response中的流就会被关闭                String result=response.body().string();                response.headers("Set-Cookie");                Log.d(TAG,"服务器返回结果（异步请求）："+result);                Bundle mBundle=new Bundle();                mBundle.putString("result",result);                Message msg=new Message();                msg.setData(mBundle);                msg.what=1;                mHandler.sendMessage(msg);            }        });    }

3.post请求上传键值对

      post请求中，在第二步创建Request对象前，需要先创建RequestBody对象来存储需要上传的不同数据

/**     * 发送POST请求，上传键值对     **/    private void okHttpPostPairs() {        //1.创建OkHttpClient 对象        OkHttpClient mOkHttpClient = new OkHttpClient();        //2.创建Request 对象，在之前，需要先创建RequestBody 对象，用来存储需要上传的数据        RequestBody body = new FormBody.Builder()                .add("login_username", "leijx")                .add("login_password", "123456")                .build();        Request request = new Request.Builder()                .url(URL)                .post(body)                .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 {                List<String> setCookieList = response.headers("Set-Cookie");                Log.i(TAG, "repose result:  " + response.body().string());            }        });    }

4.post请求上传json串

/**     * post请求     * 上传json     */    private void enqueueNet_post(){        //1.创建OkHttpClient 对象        OkHttpClient mOkHttpClient = new OkHttpClient();        //2.创建Request 对象，在之前，需要先创建RequestBody 对象，用来存储需要上传的数据        RequestBody mRequestBody = RequestBody.create(MediaType.parse("application/json;charset=utf-8"),"这是一个json串");        Request mRequest = new Request.Builder()                .url(URL)                .post(mRequestBody)                .build();        Call mCall = mOkHttpClient.newCall(mRequest);        mCall.enqueue(new Callback() {            @Override            public void onFailure(Call call, IOException e) {            }            @Override            public void onResponse(Call call, Response response) throws IOException {            }        });    }

5.post请求上传文件

/**     * POST请求，上传图片     **/    private void okHttpUpLoad() {        OkHttpClient mOkHttpClient = new OkHttpClient();        File file = new File(Environment.getExternalStorageDirectory() + "/ic_launcher.png");        //不带参数的RequestBody//        RequestBody body = RequestBody.create(MediaType.parse("image/png"),file);        //带参数的RequestBody//        MultipartBody.Builder builder = new MultipartBody.Builder();//        builder.addFormDataPart("filename", "testpng");//        builder.addFormDataPart("file", file.getName(), RequestBody.create(MediaType.parse("image/png"), file));//        RequestBody body = builder.build();        RequestBody body = new MultipartBody.Builder()                .addFormDataPart("filename", "testpng")                .addFormDataPart("file", file.getName(), RequestBody.create(MediaType.parse("image/png"), file))                .build();        Request request = new Request.Builder()                .url(URL)                .post(body)                .addHeader("Cookie", "test")                .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 {                Log.i(TAG, "upload success,   repose result:  " + response.body().string());            }        });    }

6.get请求下载文件

/**     * 下载文件     **/    private void okHttpDownload() {        OkHttpClient mOkHttpClient = new OkHttpClient();        final File file = new File(Environment.getExternalStorageDirectory().toString() + "/default.png");        Request request = new Request.Builder().url(URL).build();        Call call = mOkHttpClient.newCall(request);        call.enqueue(new Callback() {            @Override            public void onFailure(Call call, IOException e) {                Log.i(TAG, "failure: ");                e.printStackTrace();            }            @Override            public void onResponse(Call call, Response response) throws IOException {                Log.i(TAG, "onResponse");                InputStream is = null;                byte[] buf = new byte[2048];                int len = 0;                FileOutputStream fos = null;                try {                    long total = response.body().contentLength();                    Log.e(TAG, "total------>" + total);                    long current = 0;                    //获取对应流                    is = response.body().byteStream();                    fos = new FileOutputStream(file);                    while ((len = is.read(buf)) != -1) {                        current += len;                        fos.write(buf, 0, len);                        Log.e(TAG, "current------>" + current);                    }                    fos.flush();                    Log.i(TAG, "download file success");                } catch (IOException e) {                    Log.e(TAG, e.toString());                } finally {                    try {                        if (is != null) {                            is.close();                        }                        if (fos != null) {                            fos.close();                        }                    } catch (IOException e) {                        Log.e(TAG, e.toString());                    }                }            }        });    }