list_objects.md

ListObjects Example

Code Snippet

Initialize the Bucket service with access-key-id and secret-access-key

EnvContext env = new EnvContext(accessKey,accessSecret);
String zoneKey = "pek3a";
String bucketName = "testBucketName";
Bucket bucket = new Bucket(env, zoneKey, bucketName);

then you can list objects

Bucket.ListObjectsInput input = new Bucket.ListObjectsInput();
input.setLimit(20);
Bucket.ListObjectsOutput listObjectsOutput = bucket.listObjects(input);
List<KeyModel> objectKeys = listObjectsOutput.getKeys();

Add some options when list bucket objects

You can set options below in ListObjectsInput. See controlled API Docs.

Parameter name	Type	Description	Required
prefix	String	Limits the response to keys that begin with the specified prefix.	No
delimiter	Char	A delimiter is a character you use to group keys. If you specify a prefix, all keys that contain the same string between the prefix and the first occurrence of the delimiter after the prefix are grouped under a single result element called CommonPrefixes.	No
marker	String	Specifies the key to start with when listing objects in a bucket.	No
limit	Integer	Sets the maximum number of objects returned in the response body. Default is 200, maximum is 1000.	No

Below codes show objects sort by name in the folder test.

String next_marker = listObjects(bucket, "test/", "");

If the return value is not empty, the next page of data can be accessed further:

if (null != next_marker && !"".equals(next_marker.trim())) {
    // Page 2.  第二页
    String page2NextMarker = examples.listObjects(bucket, "", next_marker);
    // ...
}

    /**
     * List objects start with prefix(folderName), after a object named marker. Limit up to 100 data.
     * 列取所有前缀为 prefix(folderName) ，在 marker 之后的对象。每次最多 100 条数据。
     * @param bucket bucket
     * @param prefix prefix(folderName)
     * @param marker View the data on the next page. The marker is the value of next_marker returned by the last Response
     *               查看下一页的数据。marker 为上一次 Response 返回的 next_marker 的值
     * @return next_marker
     */
    public String listObjects(Bucket bucket, String prefix, String marker) {
        Bucket.ListObjectsInput input = new Bucket.ListObjectsInput();
        if (null != prefix && !"".equals(prefix)) {
            // Only show objects name start with 'prefix'
            input.setPrefix(prefix);
        }

        if (null != marker && !"".equals(marker)) {
            // Sort by name after a object named marker
            input.setMarker(marker);
        }

        input.setDelimiter("/");
        input.setLimit(100); // Default 200, max 1000
        try {
            Bucket.ListObjectsOutput output = bucket.listObjects(input);
            if (output.getStatueCode() == 200) {
                // Success
                System.out.println("List Objects success.");

                System.out.println("=======List Objects:Folders======");
                List<String> commonPrefixes = output.getCommonPrefixes();
                for (String folderName : commonPrefixes) {
                    System.out.println("folderName = " + folderName);
                }
                System.out.println("=======List Objects:Files======");
                List<Types.KeyModel> keys = output.getKeys();
                if (keys != null && keys.size() > 0) {
                    System.out.println("keys = " + new Gson().toJson(keys));
                }
                System.out.println("=============");

                return output.getNextMarker();
            } else {
                // Failed
                System.out.println("List Objects failed.");
                handleError(output);
            }
        } catch (QSException e) {
            // NetWork exception
            e.printStackTrace();
        }

        return null;
    }