Retrofit2的上传下载
近段时间一直在看Retrofit2和RxJava，收集了不少相关资料，文件的上传下载有时候我们需要知道一个进度，用于给用户提供一个友好的交互提示，要实现这个功能，需要在过程中额外的加入统计，正好okhttp提供一个 Interceptor 拦截器。
下载
首先定义一个api，加上 @Streaming 是为了防止在大文件的情况的下可能会导致OOM，没有注入，在Monitors的Memory里看到内存一直增长，也就是说过程中一直持续保存在内存，直到下载完成后才会向内存读取写入，而加入后就会边接收边写入，完成合理的IO，内存就不会波动很大。
返回值就需要的一个ResponseBody，文件的写入就需要这个来获取。
定义一个api
/**
* beware with large files
*/
@Streaming
@GET("downlad")
Observable<ResponseBody> download();
如何保存文件
只需要在map操作符里处理就可以
.map(r -> writeResponseBodyToDisk(response, path, name))
/**
* IO写入sdcard
*/
private static boolean writeResponseBodyToDisk(ResponseBody response, String path, String name) {
try {
// todo change the file location/name according to your needs
File futureStudioIconFile = new File(path, name);
InputStream inputStream = null;
OutputStream outputStream = null;
try {
byte[] fileReader = new byte[4096];
long fileSize = response.contentLength();
long fileSizeDownloaded = 0;
inputStream = response.byteStream();
outputStream = new FileOutputStream(futureStudioIconFile);
while (true) {
int read = inputStream.read(fileReader);
if (read == -1) {
break;
}
outputStream.write(fileReader, 0, read);
fileSizeDownloaded += read;
Logger.t("writeResponseBodyToDisk").d("file download: " + fileSizeDownloaded + " of " + fileSize);
}
outputStream.flush();
return true;
} catch (IOException e) {
Logger.t("IOException").d("file download: " + e.getMessage());
return false;
} finally {
if (inputStream != null) {
inputStream.close();
}
if (outputStream != null) {
outputStream.close();
}
}
} catch (IOException e) {
return false;
}
}
下载监听接口
下载拦截监听进度的接口
public interface DownloadListener {
/**
* @param bytesRead 已下载
* @param contentLength 总大小
* @param done 下载是否完成
*/
void update(long bytesRead, long contentLength, boolean done);
}
下载拦截器
public class DownloadInterceptor implements Interceptor {
private DownloadListener progressListener;
public DownloadInterceptor(DownloadListener progressListener) {
this.progressListener = progressListener;
}
@Override
public Response intercept(Chain chain) throws IOException {
Response originalResponse = chain.proceed(chain.request());
return originalResponse.newBuilder()
.body(new DownloadProgressResponseBody(originalResponse.body(), progressListener))
.build();
}
private static class DownloadProgressResponseBody extends ResponseBody {
private final ResponseBody responseBody;
private final DownloadListener progressListener;
private BufferedSource bufferedSource;
public DownloadProgressResponseBody(ResponseBody responseBody, DownloadListener progressListener) {
this.responseBody = responseBody;
this.progressListener = progressListener;
}
@Override
public MediaType contentType() {
return responseBody.contentType();
}
@Override
public long contentLength() {
return responseBody.contentLength();
}
@Override
public BufferedSource source() {
if (bufferedSource == null) {
bufferedSource = Okio.buffer(source(responseBody.source()));
}
return bufferedSource;
}
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);
// read() returns the number of bytes read, or -1 if this source is exhausted.
totalBytesRead += bytesRead != -1 ? bytesRead : 0;
if (null != progressListener) {
progressListener.update(totalBytesRead, responseBody.contentLength(), bytesRead == -1);
}
return bytesRead;
}
};
}
}
}
OkHttpClient监听
在获取一个Retrofit时在OkHttpClient加入拦截器就可以监听
OkHttpClient okHttpClient = new OkHttpClient()
.newBuilder()
.addInterceptor(new DownloadInterceptor(listener))
.build();
上传
Http的上传head需要定义Content-Type: multipart/form-data;
Retrofit2的在上传要注入@Multipart，参数就@PartMap或@Part
定义api
@Multipart
@POST("upload")
Observable<String> upload(@PartMap Map<String, RequestBody> params);
参数的规范
使用 PartMap
partMap.put("参数名\"; filename=\"文件名\", file);
// or 自定义文件名
partMap.put("参数名\"; filename=\"" + filename + "\"", file);
filename要写，发现不写会上传失败，至于文件名无所谓，但必须包括文件格式，服务器需要知道文件名那就另当别论
这里有个规范说得比较清楚春上冰月
RequestBody body = RequestBody.create(MediaType.parse("image/*"), file);
Map<String, RequestBody> partMap = new HashMap<>();
partMap.put("thumb\"; filename=\"img.jpg\", body);
上传监听接口
上传拦截监听进度的接口
public interface UploadListener {
/**
* @param bytesWritten 上传的字节
* @param contentLength 总字节
*/
void onRequestProgress(long bytesWritten, long contentLength);
}
上传拦截器
public class UploadInterceptor implements Interceptor {
private UploadListener progressListener;
public UploadInterceptor(UploadListener progressListener) {
this.progressListener = progressListener;
}
@Override
public Response intercept(Interceptor.Chain chain) throws IOException {
Request originalRequest = chain.request();
if (originalRequest.body() == null) {
return chain.proceed(originalRequest);
}
Request progressRequest = originalRequest.newBuilder()
.method(originalRequest.method(), new UploadRequestBody(originalRequest.body(), progressListener))
.build();
return chain.proceed(progressRequest);
}
}
继承RequestBody
文件上传过程的进度中就从RequestBody获取
public class UploadRequestBody extends RequestBody {
protected RequestBody delegate;
protected UploadListener listener;
protected CountingSink countingSink;
public UploadRequestBody(RequestBody delegate, UploadListener listener) {
this.delegate = delegate;
this.listener = listener;
}
@Override
public MediaType contentType() {
return delegate.contentType();
}
@Override
public long contentLength() {
try {
return delegate.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);
delegate.writeTo(bufferedSink);
bufferedSink.flush();
}
protected final class CountingSink extends ForwardingSink {
private long bytesWritten = 0;
public CountingSink(Sink delegate) {
super(delegate);
}
@Override
public void write(Buffer source, long byteCount) throws IOException {
super.write(source, byteCount);
bytesWritten += byteCount;
listener.onRequestProgress(bytesWritten, contentLength());
}
}
}
OkHttpClient监听
拦截器的配置就如同下载的一样
OkHttpClient okHttpClient = new OkHttpClient()
.newBuilder()
.addInterceptor(new UploadInterceptor(listener))
.build();
ps:继承RequestBody的来源一个大神okhttp-utils，这个封装好的okhttp，也是用过还不错。
