**文件管理**
##############################
在NOS中，用户可以通过一系列的接口管理桶(Bucket)中的文件(Object)，比如ListObjects，DeleteObject，CopyObject，DoesObjectExist等。

列出桶中的文件
=============================
您可以使用NosClient::listObjects列出存储中间中的文件::
    
    <?php
    /**
     * 列出Bucket内所有目录和文件， 根据返回的nextMarker循环调用listObjects接口得到所有文件
     *
     * @param NosClient $nosClient NosClient实例
     * @param string $bucket 存储空间名称
     * @return null
     */
    function listAllObjects($nosClient, $bucket)
    {
	for ($i = 0; $i < 100; $i += 1) {
            $nosClient->putObject($bucket, "dir/obj" . strval($i), "hi");
        }
        $prefix = 'dir/';
        $delimiter = '/';
        $nextMarker = '';
        $maxkeys = 30;
        while (true) {
            $options = array(
                'delimiter' => $delimiter,
                'prefix' => $prefix,
                'max-keys' => $maxkeys,
                'marker' => $nextMarker,
            );
            var_dump($options);
            try {
                $listObjectInfo = $nosClient->listObjects($bucket, $options);
            } catch (NosException $e) {
                printf(__FUNCTION__ . ": FAILED\n");
                printf($e->getMessage() . "\n");
                return;
            }
            var_dump($listObjectInfo);
            // 得到nextMarker，从上一次listObjects读到的最后一个文件的下一个文件开始继续获取文件列表
            $nextMarker = $listObjectInfo->getNextMarker();
            $listObject = $listObjectInfo->getObjectList();
            var_dump($listObject);
            if ($nextMarker === '') {
                break;
            }
        }
	
    }

上述代码中的$options中的参数如下所示:

+------------------------+---------------------------------------------------------------------------------------------------------+
|参数                    |    说明                                                                                                 |
+========================+=========================================================================================================+
| delimiter              |用于对Object名字进行分组的字符。所有名字包含指定的前缀且第一次出现delimiter字符之间的object作为一组元素  |
+------------------------+---------------------------------------------------------------------------------------------------------+
| prefix                 |限定返回的object key必须以prefix作为前缀。注意使用prefix查询时，返回的key中仍会包含prefix                |
+------------------------+---------------------------------------------------------------------------------------------------------+
| max-keys               |限定此次返回object的最大数，如果不设定，默认为100                                                        |
+------------------------+---------------------------------------------------------------------------------------------------------+
| marker                 |设定结果从marker之后按字母排序的第一个开始返回                                                           |
+------------------------+---------------------------------------------------------------------------------------------------------+

.. note::

	上述表中的参数都是可选参数

判断文件是否存在
============================
您可以使用NosClient::doesObjectExist判断文件是否存在::

    <?php
    /**
     * 判断object是否存在
     *
     * @param NosClient $nosClient NosClient实例
     * @param string $bucket bucket名字
     * @return null
     */
    function doesObjectExist($nosClient, $bucket)
    {
        $object = "nos-php-sdk-test/upload-test-object-name.txt";
        try{
            $exist = $nosClient->doesObjectExist($bucket, $object);
        } catch(NosException $e) {
            printf(__FUNCTION__ . ": FAILED\n");
            printf($e->getMessage() . "\n");
            return;
        }
        print(__FUNCTION__ . ": OK" . "\n");
        var_dump($exist);
    }

删除单个文件
===========================
您可以使用NosClient::deleteObject删除单个需要删除的文件::

    <?php
    /**
     * 删除object
     *
     * @param NosClient $nosClient NosClient实例
     * @param string $bucket bucket名字
     * @return null
     */
    function deleteObject($nosClient, $bucket)
    {
        $object = "nos-php-sdk-test/upload-test-object-name.txt";
        try{
            $nosClient->deleteObject($bucket, $object);
        } catch(NosException $e) {
            printf(__FUNCTION__ . ": FAILED\n");
            printf($e->getMessage() . "\n");
            return;
        }
        print(__FUNCTION__ . ": OK" . "\n");
    }


删除多个文件
============================
您可以使用NosClient::deleteObjects批量删除文件::

    <?php
    /**
     * 批量删除object
     *
     * @param NosClient $nosClient NosClient实例
     * @param string $bucket bucket名字
     * @return null
     */
    function deleteObjects($nosClient, $bucket)
    {
        $objects = array();
        $objects[] = "nos-php-sdk-test/upload-test-object-name.txt";
        $objects[] = "nos-php-sdk-test/upload-test-object-name.txt.copy";
        try{
            $nosClient->deleteObjects($bucket, $objects);
        } catch(NosException $e) {
            printf(__FUNCTION__ . ": FAILED\n");
            printf($e->getMessage() . "\n");
            return;
        }
        print(__FUNCTION__ . ": OK" . "\n");
    }

拷贝文件
===========================
您可以使用NosClient::copyObject拷贝文件::

    <?php
    /**
     * 拷贝object
     *
     * @param NosClient $nosClient NosClient实例
     * @param string $bucket bucket名字
     * @return null
     */
    function copyObject($nosClient, $bucket)
    {
        $from_bucket = $bucket;
        $from_object = "nos-php-sdk-test/upload-test-object-name.txt";
        $to_bucket = $bucket;
        $to_object = $from_object . '.copy';
        try{
            $nosClient->copyObject($from_bucket, $from_object, $to_bucket, $to_object);
        } catch(NosException $e) {
            printf(__FUNCTION__ . ": FAILED\n");
            printf($e->getMessage() . "\n");
            return;
        }
        print(__FUNCTION__ . ": OK" . "\n");
    }

.. attention::

	1. 支持跨桶的文件copy

移动文件
===========================
您可以使用NosClient::moveObject移动文件::

	
    <?php
    /**
     * 移动Object
     *
     * @param NosClient $nosClient NosClient实例
     * @param string $bucket bucket名字
     * @return null
     */
    function copyObject($nosClient, $bucket)
    {
        $from_bucket = $bucket;
        $from_object = "nos-php-sdk-test/upload-test-object-name.txt";
        $to_bucket = $bucket;
        $to_object = $from_object . '.move';
        try{
            $nosClient->moveObject($from_bucket, $from_object, $to_bucket, $to_object);
        } catch(NosException $e) {
            printf(__FUNCTION__ . ": FAILED\n");
            printf($e->getMessage() . "\n");
            return;
        }
        print(__FUNCTION__ . ": OK" . "\n");
    }

.. attention::

	1.暂时不支持跨桶的文件move

修改文件元信息
==========================
暂时不提供此类方法


获取文件的文件元信息
==========================
您可以使用NosClient::getObjectMeta获取对象的元数据信息::

    <?php
    /**
     * 获取object meta, 也就是getObjectMeta接口
     *
     * @param NosClient $nosClient NosClient实例
     * @param string $bucket 存储空间名称
     * @return null
     */
    function getObjectMeta($nosClient, $bucket)
    {
        $object = "nos-php-sdk-test/upload-test-object-name.txt";
        try {
            $objectMeta = $nosClient->getObjectMeta($bucket, $object);
        } catch (NosException $e) {
            printf(__FUNCTION__ . ": FAILED\n");
            printf($e->getMessage() . "\n");
            return;
        }
        print(__FUNCTION__ . ": OK" . "\n");
        if (isset($objectMeta[strtolower('Content-Disposition')]) &&
            'attachment; filename="xxxxxx"' === $objectMeta[strtolower('Content-Disposition')]
        ) {
            print(__FUNCTION__ . ": ObjectMeta checked OK" . "\n");
        } else {
            print(__FUNCTION__ . ": ObjectMeta checked FAILED" . "\n");
        }
    }

.. attention::

	1. 获取的元数据通过一个array返回，返回值为HTTP头类型的元数据与用户自定义元数据
	2. 元数据名的大小均为小写