Java SDK 的上传和下载系列接口，包括 getObject、getObjectToFile、putObject等，均支持单链接限速功能。本文介绍如何使用单链接限速功能。
从 2.6.0 版本开始，Java SDK 支持服务端对单链接上传下载请求进行限速。
以下代码以 getObject 接口为例，展示如何使用客户端限速功能。其他上传下载接口使用方式类似。
import com.volcengine.tos.TOSV2; import com.volcengine.tos.TOSV2ClientBuilder; import com.volcengine.tos.TosClientException; import com.volcengine.tos.TosServerException; import com.volcengine.tos.model.object.GetObjectV2Input; import com.volcengine.tos.model.object.GetObjectV2Output; import com.volcengine.tos.model.object.ObjectMetaRequestOptions; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.util.Map; public class GetObjectWithTrafficLimitExample { public static void main(String[] args) { String endpoint = "your endpoint"; String region = "your region"; String accessKey = System.getenv("TOS_ACCESS_KEY"); String secretKey = System.getenv("TOS_SECRET_KEY"); String bucketName = "bucket-example"; // 对象名 String objectKey = "example_dir/example_object.txt"; // 对象数据保存的本地文件路径，需保证不存在，否则会覆盖原有文件 String filePath = "example_dir/example_file.txt"; TOSV2 tos = new TOSV2ClientBuilder().build(region, endpoint, accessKey, secretKey); // 设置下载限速 5MB/s long trafficLimit = 5 * 8 * 1024 * 1024; ObjectMetaRequestOptions options = new ObjectMetaRequestOptions(); options.setTrafficLimit(trafficLimit); GetObjectV2Input input = new GetObjectV2Input().setBucket(bucketName) .setKey(objectKey).setOptions(options); File file = new File(filePath); if (file.getParentFile() != null && !file.getParentFile().exists()) { // 此处判断文件路径的父文件夹是否存在，不存在则创建父文件夹 // 如果父文件夹不存在且不创建，直接写入会报 FileNotFoundException file.getParentFile().mkdirs(); } try(FileOutputStream fos = new FileOutputStream(file); GetObjectV2Output output = tos.getObject(input)) { if (output.getContent() != null) { byte[] buffer = new byte[4096]; int length; while ((length = output.getContent().read(buffer)) != -1) { fos.write(buffer, 0, length); } } fos.flush(); System.out.println("getObject succeed."); System.out.println("object's etag is " + output.getEtag()); System.out.println("object's lastModified is " + output.getLastModified()); System.out.println("object's crc64 value is " + output.getHashCrc64ecma()); System.out.println("object's storageClass is " + output.getStorageClass()); System.out.println("object's cacheControl is " + output.getCacheControl()); System.out.println("object's contentDisposition is " + output.getContentDisposition()); System.out.println("object's contentEncoding is " + output.getContentEncoding()); System.out.println("object's contentLanguage is " + output.getContentLanguage()); System.out.println("object's contentType is " + output.getContentType()); if (output.getCustomMetadata() != null) { System.out.println("object has custom meta data."); for (Map.Entry<String, String> entry : output.getCustomMetadata().entrySet()) { System.out.println("custom meta key: " + entry.getKey() + ", value: " + entry.getValue()); } } } catch (IOException e) { System.out.println("write data to file failed"); e.printStackTrace(); } catch (TosClientException e) { // 操作失败，捕获客户端异常，一般情况是请求参数错误，此时请求并未发送 System.out.println("getObject failed"); System.out.println("Message: " + e.getMessage()); if (e.getCause() != null) { e.getCause().printStackTrace(); } } catch (TosServerException e) { // 操作失败，捕获服务端异常，可以获取到从服务端返回的详细错误信息 // 使用限定条件下载，如果服务端返回 304/412 状态码，SDK 将抛出 TosServerException，您需要自行处理。 System.out.println("getObject failed"); System.out.println("StatusCode: " + e.getStatusCode()); System.out.println("Code: " + e.getCode()); System.out.println("Message: " + e.getMessage()); System.out.println("RequestID: " + e.getRequestID()); } catch (Throwable t) { // 作为兜底捕获其他异常，一般不会执行到这里 System.out.println("getObject failed"); System.out.println("unexpected exception, message: " + t.getMessage()); } } }
对于 uploadFile、downloadFile 和 resumableCopyObject 3个接口，设置 trafficLimit 限速参数有所不同。
以下代码以 uploadFile 接口为例，展示如何使用单链接限速功能。downloadFile 和 resumableCopyObject 接口使用方式类似。
import com.volcengine.tos.TOSV2; import com.volcengine.tos.TOSV2ClientBuilder; import com.volcengine.tos.TosClientException; import com.volcengine.tos.TosServerException; import com.volcengine.tos.model.object.UploadFileV2Input; import com.volcengine.tos.model.object.UploadFileV2Output; public class UploadFileWithTrafficLimitExample { public static void main(String[] args) { String endpoint = "your endpoint"; String region = "your region"; String accessKey = System.getenv("TOS_ACCESS_KEY"); String secretKey = System.getenv("TOS_SECRET_KEY"); String bucketName = "bucket-example"; // 对象名，模拟 example_dir 下的 example_object.txt 文件 String objectKey = "example_dir/example_object.txt"; // uploadFilePath 设置待上传的本地文件路径，建议使用绝对路径，确保文件存在，不支持上传文件夹 String uploadFilePath = "example_dir/example_file.txt"; // taskNum 设置并发上传的并发数，范围为 1-1000，默认为 1 int taskNum = 5; // partSize 设置文件分片大小，范围为 5MB-5GB，默认为 20MB long partSize = 20 * 1024 * 1024; // enableCheckpoint 设置是否开启断点续传功能，开启则会在本地记录上传进度 boolean enableCheckpoint = true; // checkpointFilePath 设置断点续传记录文件存放位置，若不设置则默认在 uploadFilePath 路径下生成 // 其格式为 {uploadFilePath}.{bucket+objectKey 的 Base64Md5 值}.upload String checkpointFilePath = "the checkpoint file path"; // uploadFile 为并发分片上传，trafficLimit 设置的是每个分片上传的限速值，而非 uploadFile 接口总限速值 long trafficLimit = 10 * 1024 * 1024; TOSV2 tos = new TOSV2ClientBuilder().build(region, endpoint, accessKey, secretKey); try { UploadFileV2Input input = new UploadFileV2Input().setBucket(bucketName).setKey(objectKey) .setFilePath(uploadFilePath).setEnableCheckpoint(enableCheckpoint) .setCheckpointFile(checkpointFilePath).setPartSize(partSize).setTaskNum(taskNum) .setTrafficLimit(trafficLimit); UploadFileV2Output output = tos.uploadFile(input); System.out.println("uploadFile succeed, object's etag is " + output.getEtag()); System.out.println("uploadFile succeed, object's crc64 is " + output.getHashCrc64ecma()); } catch (TosClientException e) { // 操作失败，捕获客户端异常，一般情况是请求参数错误，此时请求并未发送 System.out.println("uploadFile failed"); System.out.println("Message: " + e.getMessage()); if (e.getCause() != null) { e.getCause().printStackTrace(); } } catch (TosServerException e) { // 操作失败，捕获服务端异常，可以获取到从服务端返回的详细错误信息 System.out.println("uploadFile failed"); System.out.println("StatusCode: " + e.getStatusCode()); System.out.println("Code: " + e.getCode()); System.out.println("Message: " + e.getMessage()); System.out.println("RequestID: " + e.getRequestID()); } catch (Throwable t) { // 作为兜底捕获其他异常，一般不会执行到这里 System.out.println("uploadFile failed"); System.out.println("unexpected exception, message: " + t.getMessage()); } } }