判断文件是否存在（Android）

以下代码用于判断文件是否存在：

Ks3Client client = new Ks3Client("AccessKeyId", "SecretAccessKey", getApplicationContext());
client.setEndpoint("ks3-cn-beijing.ksyuncs.com");
HeadObjectRequest request = new HeadObjectRequest("bucketName", "objectKey");
client.headObject(request, new HeadObjectResponseHandler() {
    @Override
    public void onSuccess(HeadObjectRequest request, HeadObjectResult result) {
        Log.i("Head Object", "Status Code: " + result.getStatusCode());
    }

    @Override
    public void onFailure(HeadObjectRequest request, Ks3ClientException clientException, Ks3ServiceException serviceException) {
        if (clientException != null) {
            Log.e("Head Object", "ClientException: " + clientException.getMessage());
        }
        if (serviceException != null) {
            Log.e("Head Object", "ServiceException: " + serviceException.getMessage());
        }
    }
});