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前面一篇文章介绍了Retrofit2的基本使用，这篇文章接着介绍使用Retrofit2实现文件上传和文件下载，以及上传下载过程中如何实现进度的显示。
文件上传
定义接口
1 2 3 | @Multipart @POST("fileService")Call<User> uploadFile(@Part MultipartBody.Part file); |
构造请求体上传
1 2 3 4 5 | File file = new File(filePath); RequestBody body = RequestBody.create(MediaType.parse("application/otcet-stream"), file);MultipartBody.Part part = MultipartBody.Part.createFormData("file", file.getName(), body);Call<User> call = getRetrofitService().uploadOneFile(part); call.enqueue(callback); |
这样就可以将这个文件上传到服务器，但就这样上传操作不够友好，最好加上文件上传进度。而Retrofit本身是不支持文件上传进度显示的，所以就需要我们自己扩展OkHttp来实现文件上传进度。
我的做法是直接扩展一个RequestBody来实现进度显示，实现完成之后只需要将上面body进行包装转换即可
上传进度显示
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 | RetrofitCallback<User> callback = new RetrofitCallback<User>() {@Override public void onSuccess(Call<User> call, Response<User> response) {runOnUIThread(activity, response.body().toString()); //进度更新结束 } @Override public void onFailure(Call<User> call, Throwable t) {runOnUIThread(activity, t.getMessage()); //进度更新结束 } @Override public void onLoading(long total, long progress) {super.onLoading(total, progress); //此处进行进度更新 } }; RequestBody body1 = RequestBody.create(MediaType.parse("application/otcet-stream"), file);//通过该行代码将RequestBody转换成特定的FileRequestBody FileRequestBody body = new FileRequestBody(body1, callback); MultipartBody.Part part = MultipartBody.Part.createFormData("file", file.getName(), body);Call<User> call = getRetrofitService().uploadOneFile(part); call.enqueue(callback); |
回调RetrofitCallback
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | public abstract class RetrofitCallback<T> implements Callback<T> {@Override public void onResponse(Call<T> call, Response<T> response) { if(response.isSuccessful()) {onSuccess(call, response); } else {onFailure(call, new Throwable(response.message())); } } public abstract void onSuccess(Call<T> call, Response<T> response); public void onLoading(long total, long progress) {} } |
FileRequestBody
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 | /** * 扩展OkHttp的请求体，实现上传时的进度提示 * * @param <T> */ public final class FileRequestBody<T> extends RequestBody {/** * 实际请求体 */ private RequestBody requestBody; /** * 上传回调接口 */ private RetrofitCallback<T> callback; /** * 包装完成的BufferedSink */ private BufferedSink bufferedSink; public FileRequestBody(RequestBody requestBody, RetrofitCallback<T> callback) {super(); this.requestBody = requestBody; this.callback = callback; } @Override public long contentLength() throws IOException {return requestBody.contentLength(); } @Override public MediaType contentType() {return requestBody.contentType(); } @Override public void writeTo(BufferedSink sink) throws IOException { if (bufferedSink == null) {//包装 bufferedSink = Okio.buffer(sink(sink)); } //写入 requestBody.writeTo(bufferedSink); //必须调用flush，否则最后一部分数据可能不会被写入 bufferedSink.flush(); } /** * 写入，回调进度接口 * @param sink Sink * @return Sink */ private Sink sink(Sink sink) { return new ForwardingSink(sink) {//当前写入字节数 long bytesWritten = 0L; //总字节长度，避免多次调用contentLength()方法 long contentLength = 0L; @Override public void write(Buffer source, long byteCount) throws IOException {super.write(source, byteCount); if (contentLength == 0) {//获得contentLength的值，后续不再调用 contentLength = contentLength(); } //增加当前写入的字节数 bytesWritten += byteCount; //回调 callback.onLoading(contentLength, bytesWritten); } }; } } |
文件下载
接口定义
文件下载请求与普通的Get和Post请求是一样的，只是他们的返回值不一样而已，文件下载请求的返回值一般定义成ResponseBody
1 2 3 4 | //这里只举例POST方式进行文件下载 @FormUrlEncoded @POST("fileService")Call<ResponseBody> downloadFile(@Field("param") String param); |
发起请求
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | RetrofitCallback<ResponseBody> callback = new RetrofitCallback<ResponseBody>() {@Override public void onSuccess(Call<ResponseBody> call, Response<ResponseBody> response) { try {InputStream is = response.body().byteStream(); String path = Util.getSdCardPath(); File file = new File(path, "download.jpg"); FileOutputStream fos = new FileOutputStream(file); BufferedInputStream bis = new BufferedInputStream(is); byte[] buffer = new byte[1024]; int len; while ((len = bis.read(buffer)) != -1) {fos.write(buffer, 0, len); } fos.flush(); fos.close(); bis.close(); is.close(); } catch (IOException e) {e.printStackTrace(); } } @Override public void onFailure(Call<ResponseBody> call, Throwable t) {runOnUIThread(activity, t.getMessage()); } }; Call<ResponseBody> call = getRetrofitService(callback).downloadFile(param); call.enqueue(callback); |
下载进度显示
下载进度显示有两种方式实现，一种是通过OkHttp设置拦截器将ResponseBody进行转换成我们扩展后的ResponseBody（稍后介绍），另外一种则是在上面的回调Callback中将ResponseBody的流写入到文件时进行进度处理，下面分别进行介绍。
扩展ResponseBody设置OkHttp拦截器
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | private <T> RetrofitService getRetrofitService(final RetrofitCallback<T> callback) {OkHttpClient.Builder clientBuilder = new OkHttpClient.Builder(); clientBuilder.addInterceptor(new Interceptor() {@Override public okhttp3.Response intercept(Chain chain) throws IOException {okhttp3.Response response = chain.proceed(chain.request()); //将ResponseBody转换成我们需要的FileResponseBody return response.newBuilder().body(new FileResponseBody<T>(response.body(), callback)).build(); } }); Retrofit retrofit = new Retrofit.Builder() .baseUrl(BASE_URL) .client(clientBuilder.build()) .addConverterFactory(GsonConverterFactory.create()) .build(); RetrofitService service = retrofit.create(RetrofitService.class); return service ; } //通过上面的设置后，我们需要在回调RetrofitCallback中实现onLoading方法来进行进度的更新操作，与上传文件的方法相同 |
FileResponseBody
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 | /** * 扩展OkHttp的请求体，实现上传时的进度提示 * * @param <T> */ public final class FileResponseBody<T> extends ResponseBody {/** * 实际请求体 */ private ResponseBody mResponseBody; /** * 下载回调接口 */ private RetrofitCallback<T> mCallback; /** * BufferedSource */ private BufferedSource mBufferedSource; public FileResponseBody(ResponseBody responseBody, RetrofitCallback<T> callback) {super(); this.mResponseBody = responseBody; this.mCallback = callback; } @Override public BufferedSource source() { if (mBufferedSource == null) {mBufferedSource = Okio.buffer(source(mResponseBody.source())); } return mBufferedSource; } @Override public long contentLength() {return mResponseBody.contentLength(); } @Override public MediaType contentType() {return mResponseBody.contentType(); } /** * 回调进度接口 * @param source * @return Source */ private Source source(Source source) { return new ForwardingSource(source) {long totalBytesRead = 0L; @Override public long read(Buffer sink, long byteCount) throws IOException {long bytesRead = super.read(sink, byteCount); totalBytesRead += bytesRead != -1 ? bytesRead : 0; mCallback.onLoading(mResponseBody.contentLength(), totalBytesRead); return bytesRead; } }; } } |
直接在回调中进行进度更新
上面介绍了通过扩展ResponseBody同时设置OkHttp拦截器来实现进度条更新显示，另外也可以直接在请求回调onSuccess中将流转换成文件时实现进度更新，下面给出大致实现
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 | RetrofitCallback<ResponseBody> callback = new RetrofitCallback<ResponseBody>() {@Override public void onSuccess(Call<ResponseBody> call, Response<ResponseBody> response) { try {InputStream is = response.body().byteStream(); //获取文件总长度 long totalLength = is.available(); String path = Util.getSdCardPath(); File file = new File(path, "download.jpg"); FileOutputStream fos = new FileOutputStream(file); BufferedInputStream bis = new BufferedInputStream(is); byte[] buffer = new byte[1024]; int len; while ((len = bis.read(buffer)) != -1) {fos.write(buffer, 0, len); //此处进行更新操作 //len即可理解为已下载的字节数 //onLoading(len, totalLength); } fos.flush(); fos.close(); bis.close(); is.close(); //此处就代表更新结束 } catch (IOException e) {e.printStackTrace(); } } @Override public void onFailure(Call<ResponseBody> call, Throwable t) {runOnUIThread(activity, t.getMessage()); } }; |
以上就是Retrofit中文件上传下载及其进度更新显示的实现
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