判断对象是否存在

简介

本文档提供快捷查询存储桶中某个对象是否存在的示例代码。

检查对象是否存在

功能说明

检查存储桶中是否存在某个对象，此接口实际是调用了HEAD Object API来检查对象是否存在的。

方法原型

cos_status_t *cos_check_object_exist(const cos_request_options_t *options, 
                                     const cos_string_t *bucket, 
                                     const cos_string_t *object,
                                     cos_table_t *headers, 
                                     cos_object_exist_status_e *object_exist,
                                     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://cloud.tencent.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.cloud.tencent.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.cloud.tencent.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.cloud.tencent.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://cloud.tencent.com/document/product/436/13324 文档
static char TEST_OBJECT_NAME1[] = "1.txt";

void log_status(cos_status_t *s)
{
    cos_warn_log("status->code: %d", s->code);
    if (s->error_code) cos_warn_log("status->error_code: %s", s->error_code);
    if (s->error_msg) cos_warn_log("status->error_msg: %s", s->error_msg);
    if (s->req_id) cos_warn_log("status->req_id: %s", s->req_id);
}

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_check_object_exist()
{
    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;
    cos_table_t *headers = NULL;
    cos_object_exist_status_e object_exist;

    cos_pool_create(&p, NULL);
    options = cos_request_options_create(p);
    init_test_request_options(options, is_cname);
    cos_str_set(&bucket, TEST_BUCKET_NAME);
    cos_str_set(&object, TEST_OBJECT_NAME1);

    // 检查对象是否存在
    s = cos_check_object_exist(options, &bucket, &object, headers, &object_exist, &resp_headers);
    if (object_exist == COS_OBJECT_NON_EXIST) {
        printf("object: %.*s non exist.\n", object.len, object.data);
    } else if (object_exist == COS_OBJECT_EXIST) {
        printf("object: %.*s exist.\n", object.len, object.data);
    } else {
        printf("object: %.*s unknown status.\n", object.len, object.data);
        log_status(s);
    }

    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_check_object_exist();

    cos_http_io_deinitialize();

    return 0;
}