禁止覆盖同名文件
默认情况下，如果已经存在同名文件（Object）且对该文件有访问权限，则新添加的文件将覆盖原有的文件。本文介绍如何通过设置请求头x-oss-forbid-overwrite在简单上传、拷贝文件及分片上传等场景中禁止覆盖同名文件。
简单上传
以下代码用于简单上传时禁止覆盖同名文件：
#include <alibabacloud/oss/OssClient.h>
using namespace AlibabaCloud::OSS;
int main(void)
{
/*初始化OSS账号信息*/
std::string AccessKeyId = "yourAccessKeyId";
std::string AccessKeySecret = "yourAccessKeySecret";
std::string Endpoint = "yourEndpoint";
std::string BucketName = "yourBucketName";
std::string ObjectName = "yourObjectName";
/*初始化网络等资源*/
InitializeSdk();
ClientConfiguration conf;
OssClient client(Endpoint, AccessKeyId, AccessKeySecret, conf);
std::shared_ptr<std::iostream> content = std::make_shared<std::stringstream>();
*content << "test cpp sdk";
/*指定上传文件操作时是否覆盖同名Object。*/
/*不指定x-oss-forbid-overwrite时，默认覆盖同名Object。*/
/*指定x-oss-forbid-overwrite为false时，表示允许覆盖同名Object。*/
/*指定x-oss-forbid-overwrite为true时，表示禁止覆盖同名Object，如果同名Object已存在程序将报错。*/
ObjectMetaData meta;
meta.addHeader("x-oss-forbid-overwrite", "true");
PutObjectRequest request(BucketName, ObjectName, content, meta);
/*上传文件*/
auto outcome = client.PutObject(request);
if (!outcome.isSuccess()) {
/*异常处理*/
std::cout << "PutObject fail" <<
",code:" << outcome.error().Code() <<
",message:" << outcome.error().Message() <<
",requestId:" << outcome.error().RequestId() << std::endl;
ShutdownSdk();
return -1;
}
/*释放网络等资源*/
ShutdownSdk();
return 0;
}简单上传的更多详情，请参见PutObject。
拷贝文件
- 拷贝小文件
以下代码用于拷贝小文件时禁止覆盖同名文件：
#include <alibabacloud/oss/OssClient.h> using namespace AlibabaCloud::OSS; int main(void) { /*初始化OSS账号信息*/ std::string AccessKeyId = "yourAccessKeyId"; std::string AccessKeySecret = "yourAccessKeySecret"; std::string Endpoint = "yourEndpoint"; std::string SourceBucketName = "yourSourceBucketName"; std::string CopyBucketName = "yourCopyBucketName"; std::string SourceObjectName = "yourSourceObjectName"; std::string CopyObjectName = "yourCopyObjectName"; /*初始化网络等资源*/ InitializeSdk(); ClientConfiguration conf; OssClient client(Endpoint, AccessKeyId, AccessKeySecret, conf); /*指定上传文件操作时是否覆盖同名Object。*/ /*不指定x-oss-forbid-overwrite时，默认覆盖同名Object。*/ /*指定x-oss-forbid-overwrite为false时，表示允许覆盖同名Object。*/ /*指定x-oss-forbid-overwrite为true时，表示禁止覆盖同名Object，如果同名Object已存在程序将报错。*/ ObjectMetaData meta; meta.addHeader("x-oss-forbid-overwrite", "true"); CopyObjectRequest request(CopyBucketName, CopyObjectName, meta); request.setCopySource(SourceBucketName, SourceObjectName); /*拷贝文件*/ auto outcome = client.CopyObject(request); if (!outcome.isSuccess()) { /*异常处理*/ std::cout << "CopyObject fail" << ",code:" << outcome.error().Code() << ",message:" << outcome.error().Message() << ",requestId:" << outcome.error().RequestId() << std::endl; ShutdownSdk(); return -1; } /*释放网络等资源*/ ShutdownSdk(); return 0; } - 拷贝大文件
以下代码用于拷贝大文件（分片拷贝）时禁止覆盖同名文件：
#include <alibabacloud/oss/OssClient.h> #include <sstream> using namespace AlibabaCloud::OSS; int main(void) { /*初始化OSS账号信息*/ std::string AccessKeyId = "yourAccessKeyId"; std::string AccessKeySecret = "yourAccessKeySecret"; std::string Endpoint = "yourEndpoint"; std::string SourceBucketName = "yourSourceBucketName"; std::string CopyBucketName = "yourCopyBucketName"; std::string SourceObjectName = "yourSourceObjectName"; std::string CopyObjectName = "yourCopyObjectName"; /*初始化网络等资源*/ InitializeSdk(); ClientConfiguration conf; OssClient client(Endpoint, AccessKeyId, AccessKeySecret, conf); auto getObjectMetaReq = GetObjectMetaRequest(SourceBucketName, SourceObjectName); auto getObjectMetaResult = GetObjectMeta(getObjectMetaReq); if (!getObjectMetaResult.isSuccess()) { std::cout << "GetObjectMeta fail" << ",code:" << outcome.error().Code() << ",message:" << outcome.error().Message() << ",requestId:" << outcome.error().RequestId() << std::endl; ShutdownSdk(); return -1; } /*获取被拷贝文件大小*/ auto objectSize = getObjectMetaResult.result().ContentLength(); /*拷贝大文件*/ ObjectMetaData metaData; std::stringstream ssDesc; ssDesc << "/" << SourceBucketName << "/" << SourceObjectName; std::string value = ssDesc.str(); metaData.addHeader("x-oss-copy-source", value); /*指定上传文件操作时是否覆盖同名Object。*/ /*不指定x-oss-forbid-overwrite时，默认覆盖同名Object。*/ /*指定x-oss-forbid-overwrite为false时，表示允许覆盖同名Object。*/ /*指定x-oss-forbid-overwrite为true时，表示禁止覆盖同名Object，如果同名Object已存在程序将报错。*/ metaData.addHeader("x-oss-forbid-overwrite", "true"); InitiateMultipartUploadRequest initUploadRequest(BucketName, ObjectName, metaData); /*初始化分片拷贝事件*/ auto uploadIdResult = client.InitiateMultipartUpload(initUploadRequest); auto uploadId = uploadIdResult.result().UploadId(); int64_t partSize = 100 * 1024; PartList partETagList; int partCount = static_cast<int>(objectSize / partSize); /*计算分片个数*/ if (objectSize % partSize != 0) { partCount++; } /*对每一个分片进行拷贝*/ for (int i = 1; i <= partCount; i++) { auto skipBytes = partSize * (i - 1); auto size = (partSize < objectSize - skipBytes) ? partSize : (objectSize - skipBytes); auto uploadPartCopyReq = UploadPartCopyRequest(CopyBucketName, CopyObjectName, SourceBucketName, SourceObjectName,uploadId, i + 1); uploadPartCopyReq.setCopySourceRange(skipBytes, skipBytes + size -1); auto uploadPartOutcome = client.UploadPartCopy(uploadPartCopyReq); if (uploadPartOutcome.isSuccess()) { Part part(i, uploadPartOutcome.result().ETag()); partETagList.push_back(part); } else { std::cout << "UploadPartCopy fail" << ",code:" << outcome.error().Code() << ",message:" << outcome.error().Message() << ",requestId:" << outcome.error().RequestId() << std::endl; } } /*完成分片拷贝*/ CompleteMultipartUploadRequest request(CopyBucketName, CopyObjectName, partETagList, uploadId); /*指定上传文件操作时是否覆盖同名Object。*/ /*不指定x-oss-forbid-overwrite时，默认覆盖同名Object。*/ /*指定x-oss-forbid-overwrite为false时，表示允许覆盖同名Object。*/ /*指定x-oss-forbid-overwrite为true时，表示禁止覆盖同名Object，如果同名Object已存在程序将报错。*/ request.MetaData().addHeader("x-oss-forbid-overwrite", "true"); auto outcome = client.CompleteMultipartUpload(request); if (!outcome.isSuccess()) { /*异常处理*/ std::cout << "CompleteMultipartUpload fail" << ",code:" << outcome.error().Code() << ",message:" << outcome.error().Message() << ",requestId:" << outcome.error().RequestId() << std::endl; ShutdownSdk(); return -1; } /*释放网络等资源*/ ShutdownSdk(); return 0; }
拷贝文件的更多详情，请参见CopyObject。
分片上传
以下代码用于分片上传时禁止覆盖同名文件：
#include <alibabacloud/oss/OssClient.h>
int64_t getFileSize(const std::string& file)
{
std::fstream f(file, std::ios::in | std::ios::binary);
f.seekg(0, f.end);
int64_t size = f.tellg();
f.close();
return size;
}
using namespace AlibabaCloud::OSS;
int main(void)
{
/*初始化OSS账号信息*/
std::string AccessKeyId = "yourAccessKeyId";
std::string AccessKeySecret = "yourAccessKeySecret";
std::string Endpoint = "yourEndpoint";
std::string BucketName = "yourBucketName";
std::string ObjectName = "yourObjectName";
/*初始化网络等资源*/
InitializeSdk();
ClientConfiguration conf;
OssClient client(Endpoint, AccessKeyId, AccessKeySecret, conf);
/*指定上传文件操作时是否覆盖同名Object。*/
/*不指定x-oss-forbid-overwrite时，默认覆盖同名Object。*/
/*指定x-oss-forbid-overwrite为false时，表示允许覆盖同名Object。*/
/*指定x-oss-forbid-overwrite为true时，表示禁止覆盖同名Object，如果同名Object已存在程序将报错。*/
ObjectMetaData meta;
data.addHeader("x-oss-forbid-overwrite", "true");
InitiateMultipartUploadRequest initUploadRequest(BucketName, ObjectName, data);
/*初始化分片上传事件*/
auto uploadIdResult = client.InitiateMultipartUpload(initUploadRequest);
auto uploadId = uploadIdResult.result().UploadId();
std::string fileToUpload = "yourLocalFilename";
int64_t partSize = 100 * 1024;
PartList partETagList;
auto fileSize = getFileSize(fileToUpload);
int partCount = static_cast<int>(fileSize / partSize);
/*计算分片个数*/
if (fileSize % partSize != 0) {
partCount++;
}
/*对每一个分片进行上传*/
for (int i = 1; i <= partCount; i++) {
auto skipBytes = partSize * (i - 1);
auto size = (partSize < fileSize - skipBytes) ? partSize : (fileSize - skipBytes);
std::shared_ptr<std::iostream> content = std::make_shared<std::fstream>(fileToUpload, std::ios::in|std::ios::binary);
content->seekg(skipBytes, std::ios::beg);
UploadPartRequest uploadPartRequest(BucketName, ObjectName, content);
uploadPartRequest.setContentLength(size);
uploadPartRequest.setUploadId(uploadId);
uploadPartRequest.setPartNumber(i);
auto uploadPartOutcome = client.UploadPart(uploadPartRequest);
if (uploadPartOutcome.isSuccess()) {
Part part(i, uploadPartOutcome.result().ETag());
partETagList.push_back(part);
}
else {
std::cout << "uploadPart fail" <<
",code:" << uploadPartOutcome.error().Code() <<
",message:" << uploadPartOutcome.error().Message() <<
",requestId:" << uploadPartOutcome.error().RequestId() << std::endl;
}
}
/*完成分片上传*/
CompleteMultipartUploadRequest request(BucketName, ObjectName);
request.setUploadId(uploadId);
request.setPartList(partETagList);
/*指定上传文件操作时是否覆盖同名Object。*/
/*不指定x-oss-forbid-overwrite时，默认覆盖同名Object。*/
/*指定x-oss-forbid-overwrite为false时，表示允许覆盖同名Object。*/
/*指定x-oss-forbid-overwrite为true时，表示禁止覆盖同名Object，如果同名Object已存在程序将报错。*/
request.MetaData().addHeader("x-oss-forbid-overwrite", "true");
auto outcome = client.CompleteMultipartUpload(request);
if (!outcome.isSuccess()) {
/*异常处理*/
std::cout << "CompleteMultipartUpload fail" <<
",code:" << outcome.error().Code() <<
",message:" << outcome.error().Message() <<
",requestId:" << outcome.error().RequestId() << std::endl;
ShutdownSdk();
return -1;
}
/*释放网络等资源*/
ShutdownSdk();
return 0;
}分片上传的更多详情，请参见InitiateMultipartUpload以及CompleteMultipartUpload。
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