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AWS S3 with Java

March 28, 2019 Faiz Akram

In this tutorial, we’ll learn how to interact with the Amazon S3 (Simple Storage Service) storage system programmatically, from Java.

Remember that S3 has a very simple structure — each bucket can store any number of objects which can be accessed using either a SOAP interface or a REST-style API.

Going forward, we’ll use the AWS SDK for Java to create, list, and delete S3 buckets. We’ll also upload, list, download and delete objects within these buckets.

/** Add the Given Dependency
  <dependency>
			<groupId>com.amazonaws</groupId>
			<artifactId>aws-java-sdk</artifactId>
			<version>1.11.163</version>
		</dependency>
*/
import java.io.IOException;
import java.io.InputStream;

import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.AWSStaticCredentialsProvider;
import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.model.DeleteObjectsRequest;
import com.amazonaws.services.s3.model.ObjectListing;
import com.amazonaws.services.s3.model.PutObjectResult;
import com.amazonaws.services.s3.model.S3Object;

public class S3Main {
	/**
	 * Get Basic AWS Credentials
	 * @param accesskey
	 * @param secretkey
	 * @return
	 */
	public AWSCredentials getBasicAWSCredentials(String accesskey, String secretkey) {
		return new BasicAWSCredentials(accesskey, secretkey);
	}

	/**
	 * get AmazonS3
	 * 
	 * @return
	 */
	public AmazonS3 getAmazonS3() {
		return AmazonS3ClientBuilder.standard()
				.withCredentials(new AWSStaticCredentialsProvider(
						getBasicAWSCredentials("<AWS accesskey>", "<AWS secretkey>")))
				.withRegion(Regions.US_EAST_1).build();
	}

	/**
	 * upload On S3
	 * 
	 * @param bucketName
	 * @param fileName
	 * @param file
	 * @return
	 */
	public PutObjectResult uploadOnS3(String bucketName, String fileName, InputStream file) {
		return getAmazonS3().putObject(bucketName, fileName, file, null);
	}

	/**
	 * get All Objects
	 * 
	 * @param bucketName
	 * @return
	 */
	public ObjectListing getAllObjects(String bucketName) {
		return getAmazonS3().listObjects(bucketName);
	}

	/**
	 * download Object
	 * 
	 * @param bucketName
	 * @param fileName
	 * @return
	 */
	public S3Object downloadObject(String bucketName, String fileName) {
		return getAmazonS3().getObject(bucketName, fileName);
	}
	/**
	 * Delete Object
	 * @param bucketName
	 * @param fileName
	 */
	public void deleteObject(String bucketName, String fileName) {
		getAmazonS3().deleteObject(bucketName, fileName);
	}
	/**
	 * Delete Multiple file
	 * @param bucketName
	 * @param fileNames
	 */
	public void deleteMultipleObjects(String bucketName, String[] fileNames) {
		DeleteObjectsRequest delObjReq = new DeleteObjectsRequest(bucketName)
				  .withKeys(fileNames);
		getAmazonS3().deleteObjects(delObjReq);
		
	}

	public static void main(String[] args) throws IOException {
		S3Main s3Main = new S3Main();
		String bucketName = "<BUCKET_NAME>";
		String path = "<PATH_NAME>";
		// Get All Object On S3
		/*
		 * ObjectListing objectListing = s3Main.getAllObjects(bucketName); for
		 * (S3ObjectSummary os : objectListing.getObjectSummaries()) {
		 * System.out.println(os.getKey()); }
		 */
		// Uplaod File
		/*
		 * File initialFile = new File("C:\\Users\\13615\\Downloads\\qq.jpeg");
		 * InputStream targetStream = new FileInputStream(initialFile); PutObjectResult
		 * result = s3Main.uploadOnS3(bucketName, path+initialFile.getName(),
		 * targetStream); System.out.println(result.getContentMd5());
		 * targetStream.close();
		 */
		//Download Object
		/*S3Object s3object = s3Main.downloadObject(bucketName, path + "qq.jpeg");
		S3ObjectInputStream inputStream = s3object.getObjectContent();
		FileUtils.copyInputStreamToFile(inputStream, new File("E:\\ImageStore\\hello.jpeg"));*/
		
		//Delete Object
		/*s3Main.deleteObject(bucketName, path + "qq.jpeg");*/
		
		//Delete Multiple File
		/*String fileNames[] = {"<<filename1>>","<<filename2>>"};
		s3Main.deleteMultipleObjects(bucketName, fileNames);*/
	}

	

}

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/** Add the Given Dependency

<groupId>com.amazonaws</groupId>

</dependency>

import java.io.IOException;

import java.io.InputStream;

import com.amazonaws.auth.AWSCredentials;

import com.amazonaws.auth.AWSStaticCredentialsProvider;

import com.amazonaws.auth.BasicAWSCredentials;

import com.amazonaws.regions.Regions;

import com.amazonaws.services.s3.AmazonS3;

import com.amazonaws.services.s3.AmazonS3ClientBuilder;

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

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

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

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

public class S3Main {

/**

* Get Basic AWS Credentials

* @param accesskey

* @param secretkey

* @return

public AWSCredentials getBasicAWSCredentials(String accesskey, String secretkey) {

return new BasicAWSCredentials(accesskey, secretkey);

}

/**

* get AmazonS3

* @return

public AmazonS3 getAmazonS3() {

return AmazonS3ClientBuilder.standard()

.withCredentials(new AWSStaticCredentialsProvider(

getBasicAWSCredentials("<AWS accesskey>", "<AWS secretkey>")))

.withRegion(Regions.US_EAST_1).build();

}

/**

* upload On S3

* @param bucketName

* @param fileName

* @param file

* @return

public PutObjectResult uploadOnS3(String bucketName, String fileName, InputStream file) {

return getAmazonS3().putObject(bucketName, fileName, file, null);

}

/**

* get All Objects

* @param bucketName

* @return

public ObjectListing getAllObjects(String bucketName) {

return getAmazonS3().listObjects(bucketName);

}

/**

* download Object

* @param bucketName

* @param fileName

* @return

public S3Object downloadObject(String bucketName, String fileName) {

return getAmazonS3().getObject(bucketName, fileName);

}

/**

* Delete Object

* @param bucketName

* @param fileName

public void deleteObject(String bucketName, String fileName) {

getAmazonS3().deleteObject(bucketName, fileName);

}

/**

* Delete Multiple file

* @param bucketName

* @param fileNames

public void deleteMultipleObjects(String bucketName, String[] fileNames) {

DeleteObjectsRequest delObjReq = new DeleteObjectsRequest(bucketName)

.withKeys(fileNames);

getAmazonS3().deleteObjects(delObjReq);

}

public static void main(String[] args) throws IOException {

S3Main s3Main = new S3Main();

String bucketName = "<BUCKET_NAME>";

String path = "<PATH_NAME>";

// Get All Object On S3

* ObjectListing objectListing = s3Main.getAllObjects(bucketName); for

* (S3ObjectSummary os : objectListing.getObjectSummaries()) {

* System.out.println(os.getKey()); }

// Uplaod File

* File initialFile = new File("C:\\Users\\13615\\Downloads\\qq.jpeg");

* InputStream targetStream = new FileInputStream(initialFile); PutObjectResult

* result = s3Main.uploadOnS3(bucketName, path+initialFile.getName(),

* targetStream); System.out.println(result.getContentMd5());

* targetStream.close();

//Download Object

/*S3Object s3object = s3Main.downloadObject(bucketName, path + "qq.jpeg");

S3ObjectInputStream inputStream = s3object.getObjectContent();

FileUtils.copyInputStreamToFile(inputStream, new File("E:\\ImageStore\\hello.jpeg"));*/

//Delete Object

/*s3Main.deleteObject(bucketName, path + "qq.jpeg");*/

//Delete Multiple File

/*String fileNames[] = {"<<filename1>>","<<filename2>>"};

s3Main.deleteMultipleObjects(bucketName, fileNames);*/

}

Image Compress JPG and PNG file

January 17, 2019 Faiz Akram

public static byte[] compress(BufferedImage image, float scale) throws IOException {
	    ByteArrayOutputStream baos = new ByteArrayOutputStream();
	    Iterator<ImageWriter> writers = ImageIO.getImageWritersByFormatName("jpg");//jpg
	    ImageWriter writer = writers.next();
	    ImageWriteParam param = writer.getDefaultWriteParam();
	    param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
	    param.setCompressionQuality(scale);
	    ImageOutputStream ios = ImageIO.createImageOutputStream(baos);
	    writer.setOutput(ios);
	    writer.write(null, new IIOImage(image, null, null), param);
	    byte[] data = baos.toByteArray();
	    ios.close();
	    baos.close();
	    writer.dispose();
	    return data;
	}

public static byte[] compress(BufferedImage image, float scale) throws IOException {

ByteArrayOutputStream baos = new ByteArrayOutputStream();

Iterator<ImageWriter> writers = ImageIO.getImageWritersByFormatName("jpg");//jpg

ImageWriter writer = writers.next();

ImageWriteParam param = writer.getDefaultWriteParam();

param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);

param.setCompressionQuality(scale);

ImageOutputStream ios = ImageIO.createImageOutputStream(baos);

writer.setOutput(ios);

writer.write(null, new IIOImage(image, null, null), param);

byte[] data = baos.toByteArray();

ios.close();

baos.close();

writer.dispose();

return data;

}

Registering a SQL function with JPA and Hibernate

September 29, 2018 Faiz Akram

Registering a SQL function with JPA and Hibernate

//Add Hibernate Properties
        properties.put("hibernate.dialect",
                        "com.sparkslink.web.config.sql.RegisterSqlFunction");

        //Create A Class 
        public class RegisterSqlFunction extends MySQLDialect {

            public RegisterSqlFunction() {
                super();
                registerFunction("group_concat", new StandardSQLFunction("group_concat", StandardBasicTypes.STRING));
            }
        }

        //Dao Method

        public List<Client> getTest() {
                Query query = getSession()
                        .createQuery("SELECT sl.name as name ,group_concat(sl.domain) as domain FROM SlClient sl GROUP BY sl.name");
                query.setResultTransformer(Transformers.aliasToBean(Client.class));
                return query.list();
            }
//DTO Class
    public class Client {
        private String name;
        private String domain;
    //Getter 
    //Setter
    }

//Add Hibernate Properties

properties.put("hibernate.dialect",

"com.sparkslink.web.config.sql.RegisterSqlFunction");

//Create A Class

public class RegisterSqlFunction extends MySQLDialect {

public RegisterSqlFunction() {

super();

registerFunction("group_concat", new StandardSQLFunction("group_concat", StandardBasicTypes.STRING));

}

//Dao Method

public List<Client> getTest() {

Query query = getSession()

.createQuery("SELECT sl.name as name ,group_concat(sl.domain) as domain FROM SlClient sl GROUP BY sl.name");

query.setResultTransformer(Transformers.aliasToBean(Client.class));

return query.list();

}

//DTO Class

public class Client {

private String name;

private String domain;

//Getter

//Setter

}

Lambda Expressions best Practices Example

August 11, 2018September 29, 2018 Faiz Akram

Lambda Expressions best Practices Example

//============================================== Convert Class into Map using Java 8 =========================================
//List to Map with Key Mapper and Value Mapper
List<String> list = new ArrayList<>();
list.add("Faiz");
list.add("Akram");
list.add("Ankur");
Map<String, Object> map = list.stream().collect(Collectors.toMap(Function.identity(), s->s));
map.forEach((x, y) -> System.out.println("Key: " + x +", value: "+ y));
//Output
/*Key: Faiz, value: Faiz
  Key: Akram, value: Akram
  Key: Ankur, value: Ankur */

//ist to Map with Key Mapper, Value Mapper on Class
List<Person> list = new ArrayList<>();
list.add(new Person(100, "Faiz"));
list.add(new Person(200, "Akram"));
list.add(new Person(300, "Ankur"));
Map<Integer, String> map = list.stream().collect(Collectors.toMap(Person::getId, Person::getName));
map.forEach((x, y) -> System.out.println("Key: " + x +", value: "+ y));
//Output
/*
  Key: 100, value: Faiz
  Key: 200, value: Akram
  Key: 300, value: Ankur */

//List to Map with Key Mapper, Value Mapper and Merge Function

List<Person> list = new ArrayList<>();
list.add(new Person(100, "Faiz"));
list.add(new Person(100, "Akram"));
list.add(new Person(300, "Ankur"));
Map<Integer, String> map = list.stream().collect(Collectors.toMap(Person::getId, Person::getName, (x, y) -> x+", "+ y));
map.forEach((x, y) -> System.out.println("Key: " + x +", value: "+ y));
//Output
/*Key: 100, value: Faiz, Akram
  Key: 300, value: Ankur */

// List to Map with Key Mapper, Value Mapper, Merge Function and Map Supplier
List<Person> list = new ArrayList<>();
list.add(new Person(100, "Faiz"));
list.add(new Person(100, "Akram"));
list.add(new Person(300, "Ankur"));
LinkedHashMap<Integer, String> map = list.stream().collect(Collectors.toMap(Person::getId, Person::getName, (x, y) -> x+", "+ y, LinkedHashMap::new));
map.forEach((x, y) -> System.out.println("Key: " + x +", value: "+ y));
//Output
/*Key: 100, value: Faiz, Akram
  Key: 300, value: Ankur */

//============================================== Get Index or object list in to Map<key, value>============================================
 List<Integer> numbers = Arrays.asList(10, 2, 3, 4, 5, 6);
 numbers.sort(Comparator.reverseOrder());
 Map<Object, Object> map = numbers.stream().collect(Collectors.toMap(i -> i, i -> numbers.indexOf(i)));
//===============================================Group By Example ===============================================
Map<String, Integer> sum = list.stream().collect(
                Collectors.groupingBy(User::getName, Collectors.summingInt(User::getAge))); // Sum of age output {Vijay=25, Dinesh=68, Kamal=15}
Map<String, Double> sum = list.stream().collect(
                Collectors.groupingBy(User::getName, Collectors.averagingInt(User::getAge))); // Average output {Vijay=25.0, Dinesh=22.666666666666668, Kamal=15.0}
Map<String, Long> sum = list.stream().collect(
                Collectors.groupingBy(User::getName, Collectors.counting())); // Count output {Vijay=1, Dinesh=3, Kamal=1}
//================================ Simple Sorting ===================================================
Collections.sort(emp, new CompartorExmaple().reversed()); // For reverse soring listing
emp.sort(Comparator.comparing(Employee:: getCity)); 
emp.sort(Comparator.comparing(Employee:: getCity).thenComparing(Employee::getName));
//===============================================String Date sorting =========================================

List<String> date = Arrays.asList("2015-11-09", "2015-11-11", "2015-11-08", "2015-11-08");
List<LocalDate> convetedSortedDate = date.stream().map(LocalDate::parse).sorted().collect(Collectors.toList());

//================================================ Sort a List of Strings Alphabetically ==============================
List<String> cities = Arrays.asList("Milan", "london", "San Francisco", "Tokyo", "New Delhi");
System.out.println(cities);
//[Milan, london, San Francisco, Tokyo, New Delhi]
cities.sort(String.CASE_INSENSITIVE_ORDER);
System.out.println(cities);
//[london, Milan, New Delhi, San Francisco, Tokyo]
cities.sort(Comparator.naturalOrder());
System.out.println(cities);
//[Milan, New Delhi, San Francisco, Tokyo, london]

//================================================== Sort a List of Integers ==========================================

List<Integer> numbers = Arrays.asList(6, 2, 1, 4, 9);
System.out.println(numbers); //[6, 2, 1, 4, 9]
numbers.sort(Comparator.naturalOrder());
System.out.println(numbers); //[1, 2, 4, 6, 9]

//========================================== Sort a List by Double Field ============================================

List<Movie> movies = Arrays.asList(
        new Movie("Lord of the rings", 8.8),
        new Movie("Back to the future", 8.5),
        new Movie("Carlito's way", 7.9),
        new Movie("Pulp fiction", 8.9));
movies.sort(Comparator.comparingDouble(Movie::getRating)
                      .reversed());
movies.forEach(System.out::println);


//========================= For remove inside the list ==========================================
List<Employee> emp = new ArrayList<Employee>();
emp.add(new Employee(1,"Faiz","Delhi"));
emp.add(new Employee(2,"Tanu","Noida"));
emp.add(new Employee(3,"Faiz","Delhi"));
emp.removeIf(employee -> employee.getCity().equals("Delhi"));
 
//===================================== Simple iterator using java 8 ====================================
emp.forEach(emp1 ->System.out.println(emp1)); 
emp.forEach(System.out::println);

//================================ Count with filter using java 8 =========================
List<String> numbers = Arrays.asList("10", "2", "3", "4", "5", "6");
Integer count1 = (int) numbers.stream().map(m -> Integer.valueOf(m)).filter(f -> f > 4 ).count();
Integer count2 = (int) numbers.stream().map(m -> Integer.valueOf(m)).filter(f -> f > 4 && f < 6).count();

//======================================= Filter Java 8 =============================

List<String> lines = Arrays.asList("spring", "node", "faiz"); //String list
List<String> result = str.stream().filter(str -> !"faiz".equals(str)).collect(Collectors.toList()); 

long sum = emp.stream().filter(e->e.getId() >= 1 && e.getId() < 3).mapToLong(u -> u.getSalary()).sum();
System.out.println(sum);

int num = list.stream().filter(u -> u.getName().endsWith("sh")).mapToInt(u -> u.getSalary()).sum();
System.out.println(num);

List<Integer> list  = Arrays.asList(3, 12, 23, 44, 20, 10, 17, 8);
System.out.println("---List with even Numbers---");
List<Integer> evenList = list.stream().filter(i -> i%2 == 0).collect(Collectors.toList());
evenList.forEach(s -> System.out.print(s+" "));
System.out.println("\n---List with odd Numbers---");
List<Integer> oddList = list.stream().filter(i -> i%2 == 1).collect(Collectors.toList());
oddList.forEach(System.out::println);

//====================================== Filter Name in List of User object ===============================
String[] name= {"Faiz", "Akram"};
List<User> present = Arrays.asList(name).stream().flatMap(x -> list .stream().filter(y -> x.equalsIgnoreCase(y.getName())))
		        .collect(Collectors.toList());

//========Map Example =====================
Map<String, Integer> items = new HashMap<>();
	items.put("A", 10);
	items.put("B", 20);
	items.put("C", 30);
	items.put("D", 40);
	items.put("E", 50);
	items.put("F", 60);
	items.forEach((k,v)->System.out.println("Item : " + k + " Count : " + v));
  items.forEach((k,v)->{
		System.out.println("Item : " + k + " Count : " + v);
		if("E".equals(k)){
			System.out.println("Hello E");
		}
	});

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//============================================== Convert Class into Map using Java 8 =========================================

//List to Map with Key Mapper and Value Mapper

List<String> list = new ArrayList<>();

list.add("Faiz");

list.add("Akram");

list.add("Ankur");

Map<String, Object> map = list.stream().collect(Collectors.toMap(Function.identity(), s->s));

map.forEach((x, y) -> System.out.println("Key: " + x +", value: "+ y));

//Output

/*Key: Faiz, value: Faiz

Key: Akram, value: Akram

Key: Ankur, value: Ankur */

//ist to Map with Key Mapper, Value Mapper on Class

List<Person> list = new ArrayList<>();

list.add(new Person(100, "Faiz"));

list.add(new Person(200, "Akram"));

list.add(new Person(300, "Ankur"));

Map<Integer, String> map = list.stream().collect(Collectors.toMap(Person::getId, Person::getName));

map.forEach((x, y) -> System.out.println("Key: " + x +", value: "+ y));

//Output

Key: 100, value: Faiz

Key: 200, value: Akram

Key: 300, value: Ankur */

//List to Map with Key Mapper, Value Mapper and Merge Function

List<Person> list = new ArrayList<>();

list.add(new Person(100, "Faiz"));

list.add(new Person(100, "Akram"));

list.add(new Person(300, "Ankur"));

Map<Integer, String> map = list.stream().collect(Collectors.toMap(Person::getId, Person::getName, (x, y) -> x+", "+ y));

map.forEach((x, y) -> System.out.println("Key: " + x +", value: "+ y));

//Output

/*Key: 100, value: Faiz, Akram

Key: 300, value: Ankur */

// List to Map with Key Mapper, Value Mapper, Merge Function and Map Supplier

List<Person> list = new ArrayList<>();

list.add(new Person(100, "Faiz"));

list.add(new Person(100, "Akram"));

list.add(new Person(300, "Ankur"));

LinkedHashMap<Integer, String> map = list.stream().collect(Collectors.toMap(Person::getId, Person::getName, (x, y) -> x+", "+ y, LinkedHashMap::new));

map.forEach((x, y) -> System.out.println("Key: " + x +", value: "+ y));

//Output

/*Key: 100, value: Faiz, Akram

Key: 300, value: Ankur */

//============================================== Get Index or object list in to Map<key, value>============================================

List<Integer> numbers = Arrays.asList(10, 2, 3, 4, 5, 6);

numbers.sort(Comparator.reverseOrder());

Map<Object, Object> map = numbers.stream().collect(Collectors.toMap(i -> i, i -> numbers.indexOf(i)));

//===============================================Group By Example ===============================================

Map<String, Integer> sum = list.stream().collect(

Collectors.groupingBy(User::getName, Collectors.summingInt(User::getAge))); // Sum of age output {Vijay=25, Dinesh=68, Kamal=15}

Map<String, Double> sum = list.stream().collect(

Collectors.groupingBy(User::getName, Collectors.averagingInt(User::getAge))); // Average output {Vijay=25.0, Dinesh=22.666666666666668, Kamal=15.0}

Map<String, Long> sum = list.stream().collect(

Collectors.groupingBy(User::getName, Collectors.counting())); // Count output {Vijay=1, Dinesh=3, Kamal=1}

//================================ Simple Sorting ===================================================

Collections.sort(emp, new CompartorExmaple().reversed()); // For reverse soring listing

emp.sort(Comparator.comparing(Employee:: getCity));

emp.sort(Comparator.comparing(Employee:: getCity).thenComparing(Employee::getName));

//===============================================String Date sorting =========================================

List<String> date = Arrays.asList("2015-11-09", "2015-11-11", "2015-11-08", "2015-11-08");

List<LocalDate> convetedSortedDate = date.stream().map(LocalDate::parse).sorted().collect(Collectors.toList());

//================================================ Sort a List of Strings Alphabetically ==============================

List<String> cities = Arrays.asList("Milan", "london", "San Francisco", "Tokyo", "New Delhi");

System.out.println(cities);

//[Milan, london, San Francisco, Tokyo, New Delhi]

cities.sort(String.CASE_INSENSITIVE_ORDER);

System.out.println(cities);

//[london, Milan, New Delhi, San Francisco, Tokyo]

cities.sort(Comparator.naturalOrder());

System.out.println(cities);

//[Milan, New Delhi, San Francisco, Tokyo, london]

//================================================== Sort a List of Integers ==========================================

List<Integer> numbers = Arrays.asList(6, 2, 1, 4, 9);

System.out.println(numbers); //[6, 2, 1, 4, 9]

numbers.sort(Comparator.naturalOrder());

System.out.println(numbers); //[1, 2, 4, 6, 9]

//========================================== Sort a List by Double Field ============================================

List<Movie> movies = Arrays.asList(

new Movie("Lord of the rings", 8.8),

new Movie("Back to the future", 8.5),

new Movie("Carlito's way", 7.9),

new Movie("Pulp fiction", 8.9));

movies.sort(Comparator.comparingDouble(Movie::getRating)

.reversed());

movies.forEach(System.out::println);

//========================= For remove inside the list ==========================================

List<Employee> emp = new ArrayList<Employee>();

emp.add(new Employee(1,"Faiz","Delhi"));

emp.add(new Employee(2,"Tanu","Noida"));

emp.add(new Employee(3,"Faiz","Delhi"));

emp.removeIf(employee -> employee.getCity().equals("Delhi"));

//===================================== Simple iterator using java 8 ====================================

emp.forEach(emp1 ->System.out.println(emp1));

emp.forEach(System.out::println);

//================================ Count with filter using java 8 =========================

List<String> numbers = Arrays.asList("10", "2", "3", "4", "5", "6");

Integer count1 = (int) numbers.stream().map(m -> Integer.valueOf(m)).filter(f -> f > 4 ).count();

Integer count2 = (int) numbers.stream().map(m -> Integer.valueOf(m)).filter(f -> f > 4 && f < 6).count();

//======================================= Filter Java 8 =============================

List<String> lines = Arrays.asList("spring", "node", "faiz"); //String list

List<String> result = str.stream().filter(str -> !"faiz".equals(str)).collect(Collectors.toList());

long sum = emp.stream().filter(e->e.getId() >= 1 && e.getId() < 3).mapToLong(u -> u.getSalary()).sum();

System.out.println(sum);

int num = list.stream().filter(u -> u.getName().endsWith("sh")).mapToInt(u -> u.getSalary()).sum();

System.out.println(num);

List<Integer> list = Arrays.asList(3, 12, 23, 44, 20, 10, 17, 8);

System.out.println("---List with even Numbers---");

List<Integer> evenList = list.stream().filter(i -> i%2 == 0).collect(Collectors.toList());

evenList.forEach(s -> System.out.print(s+" "));

System.out.println("\n---List with odd Numbers---");

List<Integer> oddList = list.stream().filter(i -> i%2 == 1).collect(Collectors.toList());

oddList.forEach(System.out::println);

//====================================== Filter Name in List of User object ===============================

String[] name= {"Faiz", "Akram"};

List<User> present = Arrays.asList(name).stream().flatMap(x -> list .stream().filter(y -> x.equalsIgnoreCase(y.getName())))

.collect(Collectors.toList());

//========Map Example =====================

Map<String, Integer> items = new HashMap<>();

items.put("A", 10);

items.put("B", 20);

items.put("C", 30);

items.put("D", 40);

items.put("E", 50);

items.put("F", 60);

items.forEach((k,v)->System.out.println("Item : " + k + " Count : " + v));

items.forEach((k,v)->{

System.out.println("Item : " + k + " Count : " + v);

if("E".equals(k)){

System.out.println("Hello E");

}

});

More updates on GitHub

Permutation of String in Java Algorithm

May 30, 2018May 30, 2018 Faiz Akram

       public static Set<String> strset = new HashSet<String>();
        public static void permutation(String str) { 
		Set<String> strSet = permutation("", str); 
		for(String st:strSet)
			System.out.println(st);
	}
	private static Set<String> permutation(String prefix, String str) {
	    int n = str.length();
	    if (n == 0) 
	    	strset.add(prefix);
	    else {
	        for (int i = 0; i < n; i++)
	            permutation(prefix + str.charAt(i), str.substring(0, i) + str.substring(i+1, n));
	    }
	    return strset;
	}

public static Set<String> strset = new HashSet<String>();

public static void permutation(String str) {

Set<String> strSet = permutation("", str);

for(String st:strSet)

System.out.println(st);

}

private static Set<String> permutation(String prefix, String str) {

int n = str.length();

if (n == 0)

strset.add(prefix);

else {

for (int i = 0; i < n; i++)

permutation(prefix + str.charAt(i), str.substring(0, i) + str.substring(i+1, n));

}

return strset;

}

We can use String class getBytes() method to encode the string into a sequence of bytes using the platform’s default charset. This method is overloaded and we can also pass Charset as argument.
Here is a simple program showing how to convert String to byte array in java.

       public static void main(String[] args) {
		String str = "Faiz";
		byte[] byteArr = name.getBytes();
		System.out.println(Arrays.toString(byteArr));
	}
//output
//[70, 97, 105, 122]

public static void main(String[] args) {

String str = "Faiz";

byte[] byteArr = name.getBytes();

System.out.println(Arrays.toString(byteArr));

}

//output

//[70, 97, 105, 122]

Ignore case while find query using Mongodb.

March 14, 2018 Faiz Akram

public List<Student> readByRhid(String emailId) {
        Query query = new Query();
        Criteria criteria = Criteria.where(LabelConstant.STUDENT_DETAIL + "." + LabelConstant.EMAILID).regex("^"+emailId+"$", "i");
        query.addCriteria(criteria);
        return mongoTemplate.find(query, Student.class);
}

public List<Student> readByRhid(String emailId) {

Query query = new Query();

Criteria criteria = Criteria.where(LabelConstant.STUDENT_DETAIL + "." + LabelConstant.EMAILID).regex("^"+emailId+"$", "i");

query.addCriteria(criteria);

return mongoTemplate.find(query, Student.class);

}

Use This Criteria

Criteria criteria = Criteria.where(LabelConstant.STUDENT_DETAIL + "." + LabelConstant.EMAILID).regex("^"+emailId+"$", "i");

1	Criteria criteria = Criteria.where(LabelConstant.STUDENT_DETAIL + "." + LabelConstant.EMAILID).regex("^"+emailId+"$", "i");

How to add CORS with Spring?

March 7, 2018March 7, 2018 Faiz Akram

1st Example For All Location

@Configuration
@EnableWebMvc
public class WebConfig extends WebMvcConfigurerAdapter {
 
    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**");
    }
}

@Configuration

@EnableWebMvc

public class WebConfig extends WebMvcConfigurerAdapter {

@Override

public void addCorsMappings(CorsRegistry registry) {

registry.addMapping("/**");

}

2nd Example For Validate which location and which method to allow

@Configuration
@EnableWebMvc
public class AppConfig extends WebMvcConfigurerAdapter {
	@Override
	public void addCorsMappings(CorsRegistry registry) {
	  registry.addMapping("/**")
	   	  .allowedOrigins("http://localhost:8585", "http://localhost:8787")
		  .allowedMethods("POST", "GET",  "PUT", "OPTIONS", "DELETE")
		  .allowedHeaders("X-Auth-Token", "Content-Type")
		  .exposedHeaders("custom-header1", "custom-header2")
		  .allowCredentials(false)
		  .maxAge(4800);
	}
}

@Configuration

@EnableWebMvc

public class AppConfig extends WebMvcConfigurerAdapter {

@Override

public void addCorsMappings(CorsRegistry registry) {

registry.addMapping("/**")

.allowedOrigins("http://localhost:8585", "http://localhost:8787")

.allowedMethods("POST", "GET", "PUT", "OPTIONS", "DELETE")

.allowedHeaders("X-Auth-Token", "Content-Type")

.exposedHeaders("custom-header1", "custom-header2")

.allowCredentials(false)

.maxAge(4800);

}

How To Register Multiple Interceptor In Spring MVC?

March 7, 2018 Faiz Akram

Create Configuration Class extends with WebMvcConfigurerAdapter

 @Override
   public void addInterceptors(InterceptorRegistry registry) {
      // Register guest interceptor with single path pattern
      registry.addInterceptor(new GuestInterceptor()).addPathPatterns("/guest");

      // Register admin interceptor with multiple path patterns
      registry.addInterceptor(new AdminInterceptor())
              .addPathPatterns(new String[] { "/admin", "/admin/*" });
   }

@Override

public void addInterceptors(InterceptorRegistry registry) {

// Register guest interceptor with single path pattern

registry.addInterceptor(new GuestInterceptor()).addPathPatterns("/guest");

// Register admin interceptor with multiple path patterns

registry.addInterceptor(new AdminInterceptor())

.addPathPatterns(new String[] { "/admin", "/admin/*" });

}

Log4j Multiple Appender Simple Example in java

February 23, 2018 Faiz Akram

# Root logger option

log4j.rootLogger=INFO, DEBUG, file,console
# Console Appender

log4j.appender.console=org.apache.log4j.ConsoleAppender

log4j.appender.console.Append=true

log4j.appender.console.layout=org.apache.log4j.PatternLayout

log4j.appender.console.layout.ConversionPattern=%d{yyyy-MM-ddHH:mm:ss,SSS} %-5p [ %M ]  ( %C )  %c{1}:%L - %m%n
# File Appender

log4j.appender.file=org.apache.log4j.FileAppender

log4j.appender.file.DatePattern='.'yyyy-MM-dd-HH-mm

log4j.appender.file.Append=true

log4j.appender.file.layout=org.apache.log4j.PatternLayout

log4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-ddHH:mm:ss,SSS} %-5p [ %M ]  ( %C )  %c{1}:%L - %m%n

log4j.appender.file.File=C:/log/SpringMain.log

log4j.appender.file.MaxBackupIndex=10