OkHttp实现MediaType为空带进度条上传文件

好的，对于这个问题，我可以给出以下的代码示例：

private void uploadFileWithProgress(String url, File file, final MediaType mediaType, final ProgressListener progressListener) {
    OkHttpClient client = new OkHttpClient.Builder()
            .addNetworkInterceptor(new Interceptor() {
                @Override
                public Response intercept(Chain chain) throws IOException {
                    Request originalRequest = chain.request();
                    Request.Builder requestBuilder = originalRequest.newBuilder()
                            .method(originalRequest.method(), new ProgressRequestBody(originalRequest.body(), progressListener));
                    return chain.proceed(requestBuilder.build());
                }
            })
            .build();

    RequestBody requestBody = RequestBody.create(mediaType, file);
    Request request = new Request.Builder()
            .url(url)
            .post(requestBody)
            .build();

    try {
        Response response = client.newCall(request).execute();
        // 处理响应结果
    } catch (IOException e) {
        e.printStackTrace();
    }
}

其中，`ProgressRequestBody` 是一个自定义的 `RequestBody`，用于在上传文件时监听上传进度。它的代码实现如下：

public class ProgressRequestBody extends RequestBody {
    private RequestBody requestBody;
    private ProgressListener progressListener;
    private CountingSink countingSink;

    public ProgressRequestBody(RequestBody requestBody, ProgressListener progressListener) {
        this.requestBody = requestBody;
        this.progressListener = progressListener;
    }

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

    @Override
    public long contentLength() {
        try {
            return requestBody.contentLength();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return -1;
    }

    @Override
    public void writeTo(BufferedSink sink) throws IOException {
        countingSink = new CountingSink(sink);
        BufferedSink bufferedSink = Okio.buffer(countingSink);
        requestBody.writeTo(bufferedSink);
        bufferedSink.flush();
    }

    private final class CountingSink extends ForwardingSink {
        private long totalBytesWritten = 0L;

        public CountingSink(Sink delegate) {
            super(delegate);
        }

        @Override
        public void write(Buffer source, long byteCount) throws IOException {
            super.write(source, byteCount);
            totalBytesWritten += byteCount;
            progressListener.onProgress(totalBytesWritten, contentLength());
        }
    }
}

然后，在调用 `uploadFileWithProgress` 方法时，只需要传入文件、媒体类型、进度监听器等参数即可：

uploadFileWithProgress(url, file, MediaType.parse("image/png"), new ProgressListener() {
    @Override
    public void onProgress(long currentBytes, long contentLength) {
        // 更新进度条
    }
});

注意，这里的 `MediaType` 必须要正确指定，否则可能会导致上传失败。另外，由于上传文件是一个比较耗时的操作，建议在子线程中执行。