public DownloadFileResult downloadFile(DownloadFileRequest downloadFileRequest) throws Throwable {
assertParameterNotNull(downloadFileRequest, "downloadFileRequest");
String bucketName = downloadFileRequest.getBucketName();
String key = downloadFileRequest.getKey();
assertParameterNotNull(bucketName, "bucketName");
assertParameterNotNull(key, "key");
ensureBucketNameValid(bucketName);
ensureObjectKeyValid(key);
// 没有指定本地文件，使用key作为本地文件名称
if (downloadFileRequest.getDownloadFile() == null) {
downloadFileRequest.setDownloadFile(downloadFileRequest.getKey());
}
// 开启断点续传，没有指定checkpoint文件，使用默认值
if (downloadFileRequest.isEnableCheckpoint()) {
if (downloadFileRequest.getCheckpointFile() == null
|| downloadFileRequest.getCheckpointFile().isEmpty()) {
downloadFileRequest.setCheckpointFile(downloadFileRequest.getDownloadFile() + ".dcp");
}
}
return downloadFileWithCheckpoint(downloadFileRequest);
}
private void prepare(
DownloadCheckPoint downloadCheckPoint, DownloadFileRequest downloadFileRequest)
throws IOException {
downloadCheckPoint.magic = DownloadCheckPoint.DOWNLOAD_MAGIC;
downloadCheckPoint.downloadFile = downloadFileRequest.getDownloadFile();
downloadCheckPoint.bucketName = downloadFileRequest.getBucketName();
downloadCheckPoint.objectKey = downloadFileRequest.getKey();
downloadCheckPoint.objectStat =
ObjectStat.getFileStat(
objectOperation, downloadCheckPoint.bucketName, downloadCheckPoint.objectKey);
downloadCheckPoint.downloadParts =
splitFile(downloadCheckPoint.objectStat.size, downloadFileRequest.getPartSize());
createFixedFile(downloadFileRequest.getDownloadFile(), downloadCheckPoint.objectStat.size);
}
private DownloadResult download(
DownloadCheckPoint downloadCheckPoint, DownloadFileRequest downloadFileRequest)
throws Throwable {
DownloadResult downloadResult = new DownloadResult();
ArrayList<PartResult> taskResults = new ArrayList<PartResult>();
ExecutorService service = Executors.newFixedThreadPool(downloadFileRequest.getTaskNum());
ArrayList<Future<PartResult>> futures = new ArrayList<Future<PartResult>>();
List<Task> tasks = new ArrayList<Task>();
for (int i = 0; i < downloadCheckPoint.downloadParts.size(); i++) {
if (!downloadCheckPoint.downloadParts.get(i).isCompleted) {
Task task =
new Task(
i, "download-" + i, downloadCheckPoint, i, downloadFileRequest, objectOperation);
futures.add(service.submit(task));
tasks.add(task);
} else {
taskResults.add(
new PartResult(
i + 1,
downloadCheckPoint.downloadParts.get(i).start,
downloadCheckPoint.downloadParts.get(i).end));
}
}
service.shutdown();
service.awaitTermination(Long.MAX_VALUE, TimeUnit.SECONDS);
for (Future<PartResult> future : futures) {
try {
PartResult tr = future.get();
taskResults.add(tr);
} catch (ExecutionException e) {
throw e.getCause();
}
}
Collections.sort(
taskResults,
new Comparator<PartResult>() {
@Override
public int compare(PartResult p1, PartResult p2) {
return p1.getNumber() - p2.getNumber();
}
});
downloadResult.setPartResults(taskResults);
if (tasks.size() > 0) {
downloadResult.setObjectMetadata(tasks.get(0).GetobjectMetadata());
}
return downloadResult;
}
private DownloadFileResult downloadFileWithCheckpoint(DownloadFileRequest downloadFileRequest)
throws Throwable {
DownloadFileResult downloadFileResult = new DownloadFileResult();
DownloadCheckPoint downloadCheckPoint = new DownloadCheckPoint();
// 开启断点续传，从checkpoint文件读取上次分片下载的结果
if (downloadFileRequest.isEnableCheckpoint()) {
// 从checkpoint文件读取上次下载结果，checkpoint文件不存在/文件被篡改/被破坏时，从新下载
try {
downloadCheckPoint.load(downloadFileRequest.getCheckpointFile());
} catch (Exception e) {
remove(downloadFileRequest.getCheckpointFile());
}
// 上传的文件修改了，从新下载
if (!downloadCheckPoint.isValid(objectOperation)) {
prepare(downloadCheckPoint, downloadFileRequest);
remove(downloadFileRequest.getCheckpointFile());
}
} else {
// 没有开启断点下载功能，从新下载
prepare(downloadCheckPoint, downloadFileRequest);
}
// 并发下载分片
DownloadResult downloadResult = download(downloadCheckPoint, downloadFileRequest);
for (PartResult partResult : downloadResult.getPartResults()) {
if (partResult.isFailed()) {
throw partResult.getException();
}
}
// 开启了断点下载，成功上传后删除checkpoint文件
if (downloadFileRequest.isEnableCheckpoint()) {
remove(downloadFileRequest.getCheckpointFile());
}
downloadFileResult.setObjectMetadata(downloadResult.getObjectMetadata());
return downloadFileResult;
}