Listing Keys Using the AWS SDK for .NET

The following C# code example lists keys in the specified bucket. The example illustrates the use of AmazonS3.ListObjects method. It also illustrates how you can specify options to list keys, such as listing keys with a specific prefix, listing keys that start after a specific marker, and listing only a specific number of keys. For instructions on how to create and test a working sample, see Testing the .NET Code Examples

using System;
using System.Configuration;
using System.Collections.Specialized;
using Amazon.S3;
using Amazon.S3.Model;

namespace s3.amazon.com.docsamples.listingkeys
{
    class S3Sample
    {
        static string bucketName = "*** Provide bucket name ***";
        static AmazonS3 client;

        public static void Main(string[] args)
        {
            if (checkRequiredFields())
            {
                NameValueCollection appConfig =
                    ConfigurationManager.AppSettings;

                string accessKeyID = appConfig["AWSAccessKey"];
                string secretAccessKeyID = appConfig["AWSSecretKey"];

                using (client = Amazon.AWSClientFactory.CreateAmazonS3Client(
                    accessKeyID, secretAccessKeyID))
                {
                   Console.WriteLine("Listing objects stored in a bucket");
                    ListingObjects();
                }
            }

            Console.WriteLine("Press any key to continue...");
            Console.ReadKey();
        }

        static void ListingObjects()
        {
            try
            {
                ListObjectsRequest request = new ListObjectsRequest();
                request = new ListObjectsRequest();
                request.BucketName = bucketName;
                request.WithPrefix("m");
                request.MaxKeys = 2;

               do
               {
                   ListObjectsResponse response = client.ListObjects(request);

                   // Process response.
                   foreach (S3Object entry in response.S3Objects)
                   {
                       Console.WriteLine("key = {0} size = {1}",
                           entry.Key, entry.Size);
                   }

                   // If response is truncated, set the marker to get the next 
                   // set of keys.
                   if (response.IsTruncated)
                   {
                       request.Marker = response.NextMarker;
                   }
                   else
                   {
                       request = null;
                   }
               } while (request != null);
            }
            catch (AmazonS3Exception amazonS3Exception)
            {
                if (amazonS3Exception.ErrorCode != null &&
                    (amazonS3Exception.ErrorCode.Equals("InvalidAccessKeyId")
                    ||
                    amazonS3Exception.ErrorCode.Equals("InvalidSecurity")))
                {
                    Console.WriteLine("Check the provided AWS Credentials.");
                    Console.WriteLine(
                    "To sign up for service, go to http://aws.amazon.com/s3");
                }
                else
                {
                    Console.WriteLine(
                     "Error occurred. Message:'{0}' when listing objects",
                     amazonS3Exception.Message);
                }
            }
        }

        static bool checkRequiredFields()
        {
            NameValueCollection appConfig = ConfigurationManager.AppSettings;

            if (string.IsNullOrEmpty(appConfig["AWSAccessKey"]))
            {
                Console.WriteLine(
                    "AWSAccessKey was not set in the App.config file.");
                return false;
            }
            if (string.IsNullOrEmpty(appConfig["AWSSecretKey"]))
            {
                Console.WriteLine(
                    "AWSSecretKey was not set in the App.config file.");
                return false;
            }
            if (string.IsNullOrEmpty(bucketName))
            {
                Console.WriteLine("The variable bucketName is not set.");
                return false;
            }

            return true;
        }
    }
}