Android知名三方库OKHttp(四) - 上传进度监听

源代码
GitHub源代码

本文目标

根据分析okhttp的源码来实现上传进度监听

文件上传进度监听

先来看下okhttp上传文件的基本写法

    private void UploadFile() {
        File file = new File(Environment.getExternalStorageDirectory(), "test.png");

        //1.1创建okHttpClient
        OkHttpClient httpClient = new OkHttpClient();

        //1.2创建RequestBody对象
        MultipartBody.Builder builder = new MultipartBody
                .Builder()
                .setType(MultipartBody.FORM);
        builder.addFormDataPart("platform", "android");
        builder.addFormDataPart("file", file.getName(),
                RequestBody.create(MediaType.parse(guessMimeType(file.getAbsolutePath())), file));

        //1.3创建Request对象
        Request request = new Request.Builder()
                .url("https://www.hyd.com/xxxxx")
                .post(builder.build()).build();

        //2.把Request对象封装成call对象
        Call call = httpClient.newCall(request);

        //3.发起异步请求
        call.enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                e.printStackTrace();
            }

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

okhttp是没有提供监听上传进度的方法的,需要我们自己去写,要怎么写呢?
首先,我们要搞明白okhttp真正把客户端数据写给服务器的地方是在 CallServerInterceptor 这个拦截器中,让我们把这行代码找出来

public final class CallServerInterceptor implements Interceptor {

  @Override
  public Response intercept(Chain chain) throws IOException {
        ......
        BufferedSink bufferedRequestBody = Okio.buffer(requestBodyOut);
        // 调用 RequestBody的writeTo方法向服务器去写数据
        request.body().writeTo(bufferedRequestBody);
        ......
  }
}

就是这行代码,我们可以分析出最终肯定会来到 MultipartBody 中的 writeTo 的方法。那么我们在这个方法里面去做处理不就行了，我们自己扩展一个 MyMultipartBody 去继承 MultipartBody 然后复写 writeTo 方法做处理，但是发现 MultipartBody 是一个 final 类，不能继承这个时候要怎么办呢?我们可以使用静态代理去实现

public class MyMultipartBody extends RequestBody {

    // 被代理的对象
    private RequestBody mRequestBody;
    //回调接口
    private UploadProgressListener mListener;
    //当前的长度
    private long mCurrentLength;
    //总长度
    private long mTotalLength;

    public MyMultipartBody(RequestBody requestBody, UploadProgressListener listener) {
        this.mRequestBody = requestBody;
        this.mListener = listener;
    }

    @Override
    public long contentLength() throws IOException {
        return mRequestBody.contentLength();
    }

    @Override
    public MediaType contentType() {
        return mRequestBody.contentType();
    }

    @Override
    public void writeTo(BufferedSink sink) throws IOException {
        //总长度
        mTotalLength = contentLength();
        //这里也是静态代理
        //把sink传进去,也是跟MyMultipartBody这个静态代理如出一辙的手法,这样可以弄个中间件过一层
        ForwardingSink forwardingSink = new ForwardingSink(sink) {
            @Override
            public void write(Buffer source, long byteCount) throws IOException {
                //写内容就会来这里,其实也是sink在写
                mCurrentLength += byteCount;
                if (mListener != null) {
                    mListener.onProgress(mTotalLength, mCurrentLength);
                }
                super.write(source, byteCount);
            }
        };
        //包装成BufferedSink
        BufferedSink buffer = Okio.buffer(forwardingSink);
        // 最终调用者还是被代理对象的方法
        mRequestBody.writeTo(buffer);
        // 刷新，RealConnection 连接池
        buffer.flush();
    }
}

然后在外界页面中,如下代码就能得到上传的实时进度,当然我们还需要用回调接口把进度返出去

    private void uploadFile() {
        File file = new File(Environment.getExternalStorageDirectory(), "test.png");
        //1.1创建okHttpClient
        OkHttpClient httpClient = new OkHttpClient();

        //1.2创建RequestBody对象(MultipartBody是继承RequestBody)
        MultipartBody.Builder builder = new MultipartBody
                .Builder()
                .setType(MultipartBody.FORM);

        builder.addFormDataPart("platform", "android");
        builder.addFormDataPart("file", file.getName(),
                RequestBody.create(MediaType.parse(guessMimeType(file.getAbsolutePath())), file));

        //1.3包装MultipartBody成MyMultipartBody
        MyMultipartBody myMultipartBody = new MyMultipartBody(builder.build(), new UploadProgressListener() {
            @Override
            public void onProgress(long total, long current) {
                //回调接口打印总进度和当前进度
                Log.e("TAG", total + " : " + current);
            }
        });

        //1.4创建Request对象
        Request request = new Request.Builder()
                .url("https://www.hyd.com/xxxxx")
                .post(myMultipartBody)
                .build();

        //2.把Request对象封装成call对象
        Call call = httpClient.newCall(request);

        //3.发起异步请求
        call.enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                e.printStackTrace();
            }

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

回调接口

public interface UploadProgressListener {
    void onProgress(long total, long current);
}

至此我们就实现了okhttp上传文件的进度监听