Stepping into the world of Amazon Web Services

WANT TO UPLOAD/ READ A FILE INTO/ FROM YOUR AWS S3 BUCKET, HERE IS A CODE SNIPPET

For any query/ suggestion drop me a note at vats.namit@gmail.com

HAPPY CODING!

import java.io.BufferedReader;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.OutputStreamWriter;

import java.io.Writer;

import org.apache.logging.log4j.LogManager;

import org.apache.logging.log4j.Logger;

import com.amazonaws.AmazonClientException;

import com.amazonaws.ClientConfiguration;

import com.amazonaws.Protocol;

import com.amazonaws.auth.AWSCredentials;

import com.amazonaws.auth.AWSCredentialsProvider;

import com.amazonaws.auth.InstanceProfileCredentialsProvider;

import com.amazonaws.auth.profile.ProfileCredentialsProvider;

import com.amazonaws.regions.Region;

import com.amazonaws.regions.Regions;

import com.amazonaws.services.s3.AmazonS3;

import com.amazonaws.services.s3.AmazonS3Client;

import com.amazonaws.services.s3.model.CannedAccessControlList;

import com.amazonaws.services.s3.model.GetObjectRequest;

import com.amazonaws.services.s3.model.PutObjectRequest;

import com.amazonaws.services.s3.model.S3Object;

import com.google.common.io.Files;

public class S3Handler {

static AmazonS3 s3;

final static EnvironmentProperty environmentProperty = new EnvironmentProperty();

private final static Logger logger = LogManager.getLogger(S3Handler.class);

// member variables

private String s3BucketName;

private File uploadFile;

private String fileName;

// Constructor for handling upload

public S3Handler(String bucketName, File file) throws Exception {

init();

setS3BucketName(bucketName);

setUploadFile(file);

setFileName(file.getName());

}

// Constructor for handling retrieval

public S3Handler(String bucketName, String fileName) throws Exception {

init();

setS3BucketName(bucketName);

setFileName(fileName);

}

// Initialize

private static void init() throws Exception {

String credentialFile = "";

   if(SystemProperty.getenv().containsKey(environmentProperty.getProperty("environment.credential.file.keyword"))) {

    credentialFile = SystemProperty.getenv(environmentProperty.getProperty("environment.credential.file.keyword"));

   }

if (credentialFile.equals(null) || credentialFile.isEmpty() || credentialFile.equals("")) {

credentialFile = "FileNotExist";

}

AWSCredentials credentials = null;

AWSCredentialsProvider credentialsProvider;

File file = new File(credentialFile);

ClientConfiguration clientConfig = new ClientConfiguration();

clientConfig.setProtocol(Protocol.HTTP);

clientConfig.setConnectionTimeout(0);

   clientConfig.setSocketTimeout(0);

if (file.exists()) {

credentialsProvider = new ProfileCredentialsProvider(credentialFile, "default");

try {

credentials = credentialsProvider.getCredentials();

} catch (Exception e) {

throw new AmazonClientException("Cannot load the credentials from the credential profiles file. "

+ "Please make sure that your credentials file is at the correct " + "location ("

+ credentialFile + "), and is in valid format.", e);

}

s3 = new AmazonS3Client(credentials, clientConfig);

} else {

credentialsProvider = new InstanceProfileCredentialsProvider();

credentials = credentialsProvider.getCredentials();

s3 = new AmazonS3Client(credentials, clientConfig);

}

String regionName = environmentProperty.getProperty("environment.region.name");

Region region = Region.getRegion(Regions.fromName(regionName));

s3.setRegion(region);

logger.info("S3 Client has been created...");

logger.info("Region is " + region.getName());

}

// setters-getters

public String getS3BucketName() {

return s3BucketName;

}

public void setS3BucketName(String s3BucketName) {

this.s3BucketName = s3BucketName;

}

public File getUploadFile() {

return uploadFile;

}

public void setUploadFile(File upFile) {

this.uploadFile = upFile;

}

public String getFileName() {

return fileName;

}

public void setFileName(String fileName) {

this.fileName = fileName;

}

// methods

/**

* method for uploading file to S3 uses the attributes set while invoking

* respective constructor

*/

public void uploadToS3() {

PutObjectRequest putObjectRequest = new PutObjectRequest(getS3BucketName(), getFileName(), getUploadFile())

.withSdkClientExecutionTimeout(Integer.valueOf(environmentProperty.getProperty("s3.clientExecution.Timeout")));

s3.putObject(putObjectRequest.withCannedAcl(CannedAccessControlList.Private));

logger.info("Upload to S3 bucket - " + getS3BucketName() + " over!");

}

/**

* method for retrieving file from S3 uses the attributes set while invoking

* respective constructor

* 

* @return json String

*/

public String retrieveS3File() {

S3Object s3object = s3.getObject(new GetObjectRequest(getS3BucketName(), getFileName()));

logger.info("Content Type  : " + s3object.getObjectMetadata().getContentType());

logger.info("Content Length: " + s3object.getObjectMetadata().getContentLength());

BufferedReader reader = new BufferedReader(new InputStreamReader(s3object.getObjectContent()));

String line;

StringBuilder output = new StringBuilder();

try {

while ((line = reader.readLine()) != null) {

output.append(line + "\r\n");

}

} catch (IOException e) {

e.printStackTrace();

}

logger.info("Retrieval from S3 bucket - " + getS3BucketName() + " over!");

return output.toString();

}

/**

* Utility to create file, can be used without having s3 client

* 

* @param fileName

* @param sb

* @return File

* @throws IOException

*/

public static File createUploadFile(String fileName, StringBuilder sb) throws IOException {

File file = new File(Files.createTempDir(), fileName + ".txt");

file.deleteOnExit();

Writer writer = new OutputStreamWriter(new FileOutputStream(file));

if (null != sb && !sb.toString().isEmpty()) {

writer.write(sb.toString());

}

writer.close();

return file;

}

}