tencent cloud

简介

本文档提供关于查询对象元数据操作相关的 API 概览以及 SDK 示例代码。

查询对象元数据

功能说明

查询对象的元数据信息。

方法原型

cos_status_t *cos_head_object(const cos_request_options_t *options, 
                            const cos_string_t *bucket, 
                            const cos_string_t *object,
                            cos_table_t *headers, 
                            cos_table_t **resp_headers);

参数说明

返回结果说明

示例

#include "cos_http_io.h"
#include "cos_api.h"
#include "cos_log.h"
// endpoint 是 COS 访问域名信息，详情请参见 https://www.tencentcloud.com/document/product/436/6224 文档
static char TEST_COS_ENDPOINT[] = "cos.ap-guangzhou.myqcloud.com";
// 开发者拥有的项目身份ID/密钥，可在 https://console.tencentcloud.com/cam/capi 页面获取
static char *TEST_ACCESS_KEY_ID;                //your secret_id
static char *TEST_ACCESS_KEY_SECRET;            //your secret_key
// 开发者访问 COS 服务时拥有的用户维度唯一资源标识，用以标识资源，可在 https://console.tencentcloud.com/cam/capi 页面获取
static char TEST_APPID[] = "<APPID>";    //your appid
//the cos bucket name, syntax: [bucket]-[appid], for example: mybucket-1253666666，可在 https://console.tencentcloud.com/cos5/bucket 查看
static char TEST_BUCKET_NAME[] = "<bucketname-appid>";    
// 对象键，对象（Object）在存储桶（Bucket）中的唯一标识。有关对象与对象键的进一步说明，请参见 https://www.tencentcloud.com/document/product/436/13324 文档
static char TEST_OBJECT_NAME1[] = "1.txt";
static void print_headers(cos_table_t *headers)
{
  const cos_array_header_t *tarr;
  const cos_table_entry_t *telts;
  int i = 0;
   if (apr_is_empty_table(headers)) {
      return;
  }
   tarr = cos_table_elts(headers);
  telts = (cos_table_entry_t*)tarr->elts;
   printf("headers:\n");
  for (; i < tarr->nelts; i++) {
      telts = (cos_table_entry_t*)(tarr->elts + i * tarr->elt_size);
      printf("%s: %s\n", telts->key, telts->val);
  }
}
void init_test_config(cos_config_t *config, int is_cname)
{
  cos_str_set(&config->endpoint, TEST_COS_ENDPOINT);
  cos_str_set(&config->access_key_id, TEST_ACCESS_KEY_ID);
  cos_str_set(&config->access_key_secret, TEST_ACCESS_KEY_SECRET);
  cos_str_set(&config->appid, TEST_APPID);
  config->is_cname = is_cname;
}
void init_test_request_options(cos_request_options_t *options, int is_cname)
{
  options->config = cos_config_create(options->pool);
  init_test_config(options->config, is_cname);
  options->ctl = cos_http_controller_create(options->pool, 0);
}
void test_head_object()
{
  cos_pool_t *p = NULL;
  int is_cname = 0;
  cos_status_t *s = NULL;
  cos_request_options_t *options = NULL;
  cos_string_t bucket;
  cos_string_t object;
  cos_table_t *resp_headers = NULL;
   //创建内存池
  cos_pool_create(&p, NULL);
   //初始化请求选项
  options = cos_request_options_create(p);
  init_test_request_options(options, is_cname);
  cos_str_set(&bucket, TEST_BUCKET_NAME);
   //获取对象元数据
  cos_str_set(&object, TEST_OBJECT_NAME1);
  s = cos_head_object(options, &bucket, &object, NULL, &resp_headers);
  print_headers(resp_headers);
  if (cos_status_is_ok(s)) {
      printf("head object succeeded\n");
  } else {
      printf("head object failed\n");
  }
   //销毁内存池
  cos_pool_destroy(p); 
}
int main(int argc, char *argv[])
{
  // 通过环境变量获取 SECRETID 和 SECRETKEY
  TEST_ACCESS_KEY_ID     = getenv("COS_SECRETID");
  TEST_ACCESS_KEY_SECRET = getenv("COS_SECRETKEY");
    if (cos_http_io_initialize(NULL, 0) != COSE_OK) {
     exit(1);
  }
   //set log level, default COS_LOG_WARN
  cos_log_set_level(COS_LOG_WARN);
   //set log output, default stderr
  cos_log_set_output(NULL);
   test_head_object();
   cos_http_io_deinitialize();
   return 0;
}