S3 的 C++ 接口实例¶
配置¶
The following contains includes and globals that will be used in later examples:
#include "libs3.h"
#include <stdlib.h>
#include <iostream>
#include <fstream>
const char access_key[] = "ACCESS_KEY";
const char secret_key[] = "SECRET_KEY";
const char host[] = "HOST";
const char sample_bucket[] = "sample_bucket";
const char sample_key[] = "hello.txt";
const char sample_file[] = "resource/hello.txt";
const char *security_token = NULL;
const char *auth_region = NULL;
S3BucketContext bucketContext =
{
host,
sample_bucket,
S3ProtocolHTTP,
S3UriStylePath,
access_key,
secret_key,
security_token,
auth_region
};
S3Status responsePropertiesCallback(
const S3ResponseProperties *properties,
void *callbackData)
{
return S3StatusOK;
}
static void responseCompleteCallback(
S3Status status,
const S3ErrorDetails *error,
void *callbackData)
{
return;
}
S3ResponseHandler responseHandler =
{
&responsePropertiesCallback,
&responseCompleteCallback
};
Creating (and Closing) a Connection¶
This creates a connection so that you can interact with the server.
S3_initialize("s3", S3_INIT_ALL, host);
// Do stuff...
S3_deinitialize();
Listing Owned Buckets¶
This gets a list of Buckets that you own. This also prints out the bucket name, owner ID, and display name for each bucket.
static S3Status listServiceCallback(
const char *ownerId,
const char *ownerDisplayName,
const char *bucketName,
int64_t creationDate, void *callbackData)
{
bool *header_printed = (bool*) callbackData;
if (!*header_printed) {
*header_printed = true;
printf("%-22s", " Bucket");
printf(" %-20s %-12s", " Owner ID", "Display Name");
printf("\n");
printf("----------------------");
printf(" --------------------" " ------------");
printf("\n");
}
printf("%-22s", bucketName);
printf(" %-20s %-12s", ownerId ? ownerId : "", ownerDisplayName ? ownerDisplayName : "");
printf("\n");
return S3StatusOK;
}
S3ListServiceHandler listServiceHandler =
{
responseHandler,
&listServiceCallback
};
bool header_printed = false;
S3_list_service(S3ProtocolHTTP, access_key, secret_key, security_token, host,
auth_region, NULL, 0, &listServiceHandler, &header_printed);
创建一个桶¶
这里创建一个新桶。
S3_create_bucket(S3ProtocolHTTP, access_key, secret_key, NULL, host, sample_bucket, S3CannedAclPrivate, NULL, NULL, &responseHandler, NULL);
罗列一个桶的内容¶
This gets a list of objects in the bucket. This also prints out each object’s name, the file size, and last modified date.
static S3Status listBucketCallback(
int isTruncated,
const char *nextMarker,
int contentsCount,
const S3ListBucketContent *contents,
int commonPrefixesCount,
const char **commonPrefixes,
void *callbackData)
{
printf("%-22s", " Object Name");
printf(" %-5s %-20s", "Size", " Last Modified");
printf("\n");
printf("----------------------");
printf(" -----" " --------------------");
printf("\n");
for (int i = 0; i < contentsCount; i++) {
char timebuf[256];
char sizebuf[16];
const S3ListBucketContent *content = &(contents[i]);
time_t t = (time_t) content->lastModified;
strftime(timebuf, sizeof(timebuf), "%Y-%m-%dT%H:%M:%SZ", gmtime(&t));
sprintf(sizebuf, "%5llu", (unsigned long long) content->size);
printf("%-22s %s %s\n", content->key, sizebuf, timebuf);
}
return S3StatusOK;
}
S3ListBucketHandler listBucketHandler =
{
responseHandler,
&listBucketCallback
};
S3_list_bucket(&bucketContext, NULL, NULL, NULL, 0, NULL, 0, &listBucketHandler, NULL);
The output will look something like this:
myphoto1.jpg 251262 2011-08-08T21:35:48.000Z
myphoto2.jpg 262518 2011-08-08T21:38:01.000Z
Deleting a Bucket¶
Note
The Bucket must be empty! Otherwise it won’t work!
S3_delete_bucket(S3ProtocolHTTP, S3UriStylePath, access_key, secret_key, 0, host, sample_bucket, NULL, NULL, 0, &responseHandler, NULL);
Creating an Object (from a file)¶
This creates a file hello.txt.
#include <sys/stat.h>
typedef struct put_object_callback_data
{
FILE *infile;
uint64_t contentLength;
} put_object_callback_data;
static int putObjectDataCallback(int bufferSize, char *buffer, void *callbackData)
{
put_object_callback_data *data = (put_object_callback_data *) callbackData;
int ret = 0;
if (data->contentLength) {
int toRead = ((data->contentLength > (unsigned) bufferSize) ? (unsigned) bufferSize : data->contentLength);
ret = fread(buffer, 1, toRead, data->infile);
}
data->contentLength -= ret;
return ret;
}
put_object_callback_data data;
struct stat statbuf;
if (stat(sample_file, &statbuf) == -1) {
fprintf(stderr, "\nERROR: Failed to stat file %s: ", sample_file);
perror(0);
exit(-1);
}
int contentLength = statbuf.st_size;
data.contentLength = contentLength;
if (!(data.infile = fopen(sample_file, "r"))) {
fprintf(stderr, "\nERROR: Failed to open input file %s: ", sample_file);
perror(0);
exit(-1);
}
S3PutObjectHandler putObjectHandler =
{
responseHandler,
&putObjectDataCallback
};
S3_put_object(&bucketContext, sample_key, contentLength, NULL, NULL, 0, &putObjectHandler, &data);
fclose(data.infile);
下载一个对象（到一文件）¶
This downloads a file and prints the contents.
static S3Status getObjectDataCallback(int bufferSize, const char *buffer, void *callbackData)
{
FILE *outfile = (FILE *) callbackData;
size_t wrote = fwrite(buffer, 1, bufferSize, outfile);
return ((wrote < (size_t) bufferSize) ? S3StatusAbortedByCallback : S3StatusOK);
}
S3GetObjectHandler getObjectHandler =
{
responseHandler,
&getObjectDataCallback
};
FILE *outfile = stdout;
S3_get_object(&bucketContext, sample_key, NULL, 0, 0, NULL, 0, &getObjectHandler, outfile);
Delete an Object¶
This deletes an object.
S3ResponseHandler deleteResponseHandler =
{
0,
&responseCompleteCallback
};
S3_delete_object(&bucketContext, sample_key, 0, 0, &deleteResponseHandler, 0);
Change an Object’s ACL¶
This changes an object’s ACL to grant full control to another user.
#include <string.h>
char ownerId[] = "owner";
char ownerDisplayName[] = "owner";
char granteeId[] = "grantee";
char granteeDisplayName[] = "grantee";
S3AclGrant grants[] = {
{
S3GranteeTypeCanonicalUser,
{{}},
S3PermissionFullControl
},
{
S3GranteeTypeCanonicalUser,
{{}},
S3PermissionReadACP
},
{
S3GranteeTypeAllUsers,
{{}},
S3PermissionRead
}
};
strncpy(grants[0].grantee.canonicalUser.id, ownerId, S3_MAX_GRANTEE_USER_ID_SIZE);
strncpy(grants[0].grantee.canonicalUser.displayName, ownerDisplayName, S3_MAX_GRANTEE_DISPLAY_NAME_SIZE);
strncpy(grants[1].grantee.canonicalUser.id, granteeId, S3_MAX_GRANTEE_USER_ID_SIZE);
strncpy(grants[1].grantee.canonicalUser.displayName, granteeDisplayName, S3_MAX_GRANTEE_DISPLAY_NAME_SIZE);
S3_set_acl(&bucketContext, sample_key, ownerId, ownerDisplayName, 3, grants, 0, &responseHandler, 0);
Generate Object Download URL (signed)¶
This generates a signed download URL that will be valid for 5 minutes.
#include <time.h>
char buffer[S3_MAX_AUTHENTICATED_QUERY_STRING_SIZE];
int64_t expires = time(NULL) + 60 * 5; // Current time + 5 minutes
S3_generate_authenticated_query_string(buffer, &bucketContext, sample_key, expires, NULL, "GET");
