PHP使用putObject的时候，如何判断上传文件是否成功

    /**
     * 获得object的meta信息
     * @param string $bucket (Required)
     * @param string $object (Required)
     * @param string $options (Optional)
     * @author xiaobing
     * @since 2011-11-14
     * @return ResponseCore
     */
    public function get_object_meta($bucket, $object, $options = NULL){
        $this->precheck_common($bucket, $object, $options);
        $options[self::OSS_BUCKET] = $bucket;
        $options[self::OSS_METHOD] = self::OSS_HTTP_HEAD;
        $options[self::OSS_OBJECT] = $object;
        return $this->auth($options);
    }

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判断res的status，如果是200，表示存在，404表示不存在