Use a operação AppendObject para acrescentar conteúdo a objetos anexáveis existentes.
Observações
Este tópico utiliza o endpoint público da região China (Hangzhou). Para acessar o OSS a partir de outros serviços da Alibaba Cloud na mesma região, use um endpoint interno. Para obter mais informações sobre regiões e endpoints do OSS, consulte Regiões e endpoints.
Este tópico demonstra como criar uma instância OSSClient com um endpoint do OSS. Para outras configurações, como uso de domínio personalizado ou autenticação com credenciais do Security Token Service (STS), consulte Inicialização (C SDK).
Se o objeto de destino não existir, a operação AppendObject criará um novo objeto anexável.
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Se o objeto de destino já existir:
Se o objeto for anexável e a posição inicial especificada for igual ao tamanho atual do objeto, os dados serão acrescentados ao final dele.
Se o objeto for anexável, mas a posição inicial especificada diferir do tamanho atual, o sistema retornará o erro PositionNotEqualToLength.
Se o objeto não for do tipo anexável, o sistema retornará o erro ObjectNotAppendable.
Permissões
Por padrão, uma conta Alibaba Cloud tem permissões totais. Usuários RAM ou funções RAM vinculados a essa conta não têm permissões iniciais. O administrador da conta deve conceder as permissões operacionais necessárias por meio de políticas do RAM ou Bucket Policy.
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API |
Ação |
Descrição |
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AppendObject |
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Use esta operação para fazer upload de um objeto acrescentando-o a um objeto existente. |
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Necessária quando tags de objeto são especificadas via x-oss-tagging durante o upload por acréscimo. |
Acrescentar dados da memória
O exemplo de código a seguir mostra como acrescentar dados da memória a um objeto em um bucket especificado:
#include "oss_api.h"
#include "aos_http_io.h"
/* Set yourEndpoint to the Endpoint of the region where the bucket is located. For example, for the China (Hangzhou) region, set the Endpoint to https://oss-cn-hangzhou.aliyuncs.com. */
const char *endpoint = "yourEndpoint";
/* Specify the bucket name. For example, examplebucket. */
const char *bucket_name = "examplebucket";
/* Specify the full path of the object. The full path cannot contain the bucket name. For example, exampledir/exampleobject.txt. */
const char *object_name = "exampledir/exampleobject.txt";
const char *object_content = "More than just cloud.";
/* Set yourRegion to the region where the bucket is located. For example, for the China (Hangzhou) region, set the region to cn-hangzhou. */
const char *region = "yourRegion";
void init_options(oss_request_options_t *options)
{
options->config = oss_config_create(options->pool);
/* Initialize the aos_string_t type with a char* string. */
aos_str_set(&options->config->endpoint, endpoint);
/* Obtain access credentials from environment variables. Before running this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set. */
aos_str_set(&options->config->access_key_id, getenv("OSS_ACCESS_KEY_ID"));
aos_str_set(&options->config->access_key_secret, getenv("OSS_ACCESS_KEY_SECRET"));
// Configure the following two parameters.
aos_str_set(&options->config->region, region);
options->config->signature_version = 4;
/* Specifies whether a CNAME is used. 0 indicates that a CNAME is not used. */
options->config->is_cname = 0;
/* Set network parameters, such as the timeout period. */
options->ctl = aos_http_controller_create(options->pool, 0);
}
int main(int argc, char *argv[])
{
/* Call the aos_http_io_initialize method at the program entry to initialize global resources, such as the network and memory. */
if (aos_http_io_initialize(NULL, 0) != AOSE_OK) {
exit(1);
}
/* The memory pool for memory management is equivalent to apr_pool_t. The implementation code is in the apr library. */
aos_pool_t *pool;
/* Create a new memory pool. The second parameter is NULL, which indicates that the new memory pool does not inherit from another memory pool. */
aos_pool_create(&pool, NULL);
/* Create and initialize options. This parameter includes global configuration information such as endpoint, access_key_id, access_key_secret, is_cname, and curl. */
oss_request_options_t *oss_client_options;
/* Allocate memory to options in the memory pool. */
oss_client_options = oss_request_options_create(pool);
/* Initialize the client options oss_client_options. */
init_options(oss_client_options);
/* Initialize parameters. */
aos_string_t bucket;
aos_string_t object;
aos_list_t buffer;
int64_t position = 0;
char *next_append_position = NULL;
aos_buf_t *content = NULL;
aos_table_t *headers1 = NULL;
aos_table_t *headers2 = NULL;
aos_table_t *resp_headers = NULL;
aos_status_t *resp_status = NULL;
aos_str_set(&bucket, bucket_name);
aos_str_set(&object, object_name);
headers1 = aos_table_make(pool, 0);
/* Get the starting append position. */
resp_status = oss_head_object(oss_client_options, &bucket, &object, headers1, &resp_headers);
if (aos_status_is_ok(resp_status)) {
next_append_position = (char*)(apr_table_get(resp_headers, "x-oss-next-append-position"));
position = atoi(next_append_position);
}
/* Append the object. */
headers2 = aos_table_make(pool, 0);
aos_list_init(&buffer);
content = aos_buf_pack(pool, object_content, strlen(object_content));
aos_list_add_tail(&content->node, &buffer);
resp_status = oss_append_object_from_buffer(oss_client_options, &bucket, &object, position, &buffer, headers2, &resp_headers);
if (aos_status_is_ok(resp_status)) {
printf("append object from buffer succeeded\n");
} else {
printf("append object from buffer failed\n");
}
/* Release the memory pool. This releases the memory allocated to resources during the request. */
aos_pool_destroy(pool);
/* Release the previously allocated global resources. */
aos_http_io_deinitialize();
return 0;
}Acrescentar dados de um arquivo local
O exemplo de código a seguir mostra como acrescentar dados de um arquivo local a um objeto em um bucket especificado:
#include "oss_api.h"
#include "aos_http_io.h"
/* Set yourEndpoint to the Endpoint of the region where the bucket is located. For example, for the China (Hangzhou) region, set the Endpoint to https://oss-cn-hangzhou.aliyuncs.com. */
const char *endpoint = "yourEndpoint";
/* Specify the bucket name. For example, examplebucket. */
const char *bucket_name = "examplebucket";
/* Specify the full path of the object. The full path cannot contain the bucket name. For example, exampledir/exampleobject.txt. */
const char *object_name = "exampledir/exampleobject.txt";
/* Specify the full path of the local file. */
const char *local_filename = "yourLocalFilename";
/* Set yourRegion to the region where the bucket is located. For example, for the China (Hangzhou) region, set the region to cn-hangzhou. */
const char *region = "yourRegion";
void init_options(oss_request_options_t *options)
{
options->config = oss_config_create(options->pool);
/* Initialize the aos_string_t type with a char* string. */
aos_str_set(&options->config->endpoint, endpoint);
/* Obtain access credentials from environment variables. Before running this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set. */
aos_str_set(&options->config->access_key_id, getenv("OSS_ACCESS_KEY_ID"));
aos_str_set(&options->config->access_key_secret, getenv("OSS_ACCESS_KEY_SECRET"));
// Configure the following two parameters.
aos_str_set(&options->config->region, region);
options->config->signature_version = 4;
/* Specifies whether a CNAME is used. 0 indicates that a CNAME is not used. */
options->config->is_cname = 0;
/* Set network parameters, such as the timeout period. */
options->ctl = aos_http_controller_create(options->pool, 0);
}
int main(int argc, char *argv[])
{
/* Call the aos_http_io_initialize method at the program entry to initialize global resources, such as the network and memory. */
if (aos_http_io_initialize(NULL, 0) != AOSE_OK) {
exit(1);
}
/* The memory pool for memory management is equivalent to apr_pool_t. The implementation code is in the apr library. */
aos_pool_t *pool;
/* Create a new memory pool. The second parameter is NULL, which indicates that the new memory pool does not inherit from another memory pool. */
aos_pool_create(&pool, NULL);
/* Create and initialize options. This parameter includes global configuration information such as endpoint, access_key_id, access_key_secret, is_cname, and curl. */
oss_request_options_t *oss_client_options;
/* Allocate memory to options in the memory pool. */
oss_client_options = oss_request_options_create(pool);
/* Initialize the client options oss_client_options. */
init_options(oss_client_options);
/* Initialize parameters. */
aos_string_t bucket;
aos_string_t object;
aos_string_t file;
int64_t position = 0;
char *next_append_position = NULL;
aos_table_t *headers1 = NULL;
aos_table_t *headers2 = NULL;
aos_table_t *resp_headers = NULL;
aos_status_t *resp_status = NULL;
aos_str_set(&bucket, bucket_name);
aos_str_set(&object, object_name);
aos_str_set(&file, local_filename);
/* Get the starting append position. */
resp_status = oss_head_object(oss_client_options, &bucket, &object, headers1, &resp_headers);
if(aos_status_is_ok(resp_status)) {
next_append_position = (char*)(apr_table_get(resp_headers, "x-oss-next-append-position"));
position = atoi(next_append_position);
}
/* Append the object. */
resp_status = oss_append_object_from_file(oss_client_options, &bucket, &object, position, &file, headers2, &resp_headers);
/* Check whether the append operation is successful. */
if (aos_status_is_ok(resp_status)) {
printf("append object from file succeeded\n");
} else {
printf("append object from file failed\n");
}
/* Release the memory pool. This releases the memory allocated to resources during the request. */
aos_pool_destroy(pool);
/* Release the previously allocated global resources. */
aos_http_io_deinitialize();
return 0;
}Referências
Para obter o código de exemplo completo de upload por acréscimo, consulte o GitHub.
Para obter mais informações sobre a operação de API de upload por acréscimo, consulte AppendObject.