下載文件__Java-SDK_SDK 參考_對象存儲 OSS-阿裏雲

提示：

• ETag的值可以通過OSSClient.getObjectMetadata獲取；
• OSSClient.getObject，OSSClient.downloadFile都支持限定條件。

下載進度條

OSS Java sdk支持進度條功能，指示上傳/下載的進度。下麵的代碼以OSSClient.getObject為例，說明進度條功能的使用。

提示：

• 下載進度條的完整代碼請參考：GitHub

static class GetObjectProgressListener implements ProgressListener {
        private long bytesRead = 0;
        private long totalBytes = -1;
        private boolean succeed = false;
        @Override
        public void progressChanged(ProgressEvent progressEvent) {
            long bytes = progressEvent.getBytes();
            ProgressEventType eventType = progressEvent.getEventType();
            switch (eventType) {
            case TRANSFER_STARTED_EVENT:
                System.out.println("Start to download......");
                break;
            case RESPONSE_CONTENT_LENGTH_EVENT:
                this.totalBytes = bytes;
                System.out.println(this.totalBytes + " bytes in total will be downloaded to a local file");
                break;
            case RESPONSE_BYTE_TRANSFER_EVENT:
                this.bytesRead += bytes;
                if (this.totalBytes != -1) {
                    int percent = (int)(this.bytesRead * 100.0 / this.totalBytes);
                    System.out.println(bytes + " bytes have been read at this time, download progress: " +
                            percent + "%(" + this.bytesRead + "/" + this.totalBytes + ")");
                } else {
                    System.out.println(bytes + " bytes have been read at this time, download ratio: unknown" +
                            "(" + this.bytesRead + "/...)");
                }
                break;
            case TRANSFER_COMPLETED_EVENT:
                this.succeed = true;
                System.out.println("Succeed to download, " + this.bytesRead + " bytes have been transferred in total");
                break;
            case TRANSFER_FAILED_EVENT:
                System.out.println("Failed to download, " + this.bytesRead + " bytes have been transferred");
                break;
            default:
                break;
            }
        }
        public boolean isSucceed() {
            return succeed;
        }
    }
public static void main(String[] args) { 
    String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
    String accessKeyId = "<accessKeyId>";
    String accessKeySecret = "<accessKeySecret>";
    String bucketName = "<bucketName>";
    String key = "object-get-progress-sample";
    OSSClient ossClient = new OSSClient(endpoint, accessKeyId, accessKeySecret);
    try {            
            // 帶進度條的下載
            client.getObject(new GetObjectRequest(bucketName, key).
                    <GetObjectRequest>withProgressListener(new GetObjectProgressListener()), 
                    new File("<yourLocalFile>"));
    } catch (Exception e) {
        e.printStackTrace();
    }
    ossClient.shutdown();
}