Registration and Login with Kotlin + Spring Security + Thymeleaf

Hello everyone, I hope you all are well, today we will learn how to create user registration and login using Kotlin, Spring security, Thymeleaf, JPA, and H2DB.GitHub repository link is provided at the end of this tutorial. You can download the source code.

Technologies used:

  • Spring Boot makes developing the web applications and microservices with Spring Framework faster and easier through three core capabilities: 1.  Autoconfiguration 2. An opinionated approach to configuration 3. The ability to create standalone applications
  • Kotlin is an open-source statically typed programming language. It is object-oriented and supports functional programming features. It is designed for the JVM (Java Virtual Machine)
  • Spring Security is a Java/Java EE framework that provides authentication, authorization, and other security features for enterprise applications.
  • Thymeleaf is a modern server-side Java template engine for both web and standalone environments.
  • Maven is a build automation tool used primarily for Java projects. Maven can also be used to build and manage projects written in C#, Ruby, Scala, and other languages.

User Interface

User Registration


User Login



Authentication success page

Project Structure:



Maven[pom.xml] 

A Project Object Model or POM is the fundamental unit of work in Maven. It is an XML file that contains information about the project and configuration details utilized by Maven to build the project. It contains default values for most projects. Some of the configurations that can be designated in the POM is the project dependencies, the plugins or goals that can be executed, the build profiles, and so on. Other information such as the project version, description, developers, mailing lists, and such can withal be designated.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
        https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.5</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.knf.dev.demo</groupId>
    <artifactId>kotlin-spring-thymeleaf-login-signup</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>kotlin-spring-thymeleaf-login-signup</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>11</java.version>
        <kotlin.version>1.5.31</kotlin.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.module</groupId>
            <artifactId>jackson-module-kotlin</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-reflect</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-stdlib-jdk8</artifactId>
        </dependency>

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <sourceDirectory>${project.basedir}/src/main/kotlin</sourceDirectory>
  <testSourceDirectory>${project.basedir}/src/test/kotlin</testSourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-maven-plugin</artifactId>
                <configuration>
                    <args>
                        <arg>-Xjsr305=strict</arg>
                    </args>
                    <compilerPlugins>
                        <plugin>spring</plugin>
                        <plugin>jpa</plugin>
                    </compilerPlugins>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-allopen</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-noarg</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                </dependencies>
            </plugin>
        </plugins>
    </build>

</project>


Create Entity Role

package com.knf.dev.demo.kotlinspringthymeleafloginsignup.model

import javax.persistence.*

@Entity
@Table(name = "role")
class Role {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    var id: Long? = null
    var name: String? = null

    constructor() {}
    constructor(name: String?) : super() {
        this.name = name
    }
}
The @Entity annotation specifies that the class is an entity and is mapped to a database table. The @Table annotation specifies the name of the database table to be used for mapping. The @Id annotation specifies the primary key of an entity and the @GeneratedValue provides for the specification of generation strategies for the values of primary keys.


Create Entity User

package com.knf.dev.demo.kotlinspringthymeleafloginsignup.model

import javax.persistence.*

@Entity
@Table(name = "user", uniqueConstraints = [UniqueConstraint(columnNames = ["email"])])
class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    var id: Long? = null

    @Column(name = "first_name")
    var firstName: String? = null

    @Column(name = "last_name")
    var lastName: String? = null
    var email: String? = null
    var password: String? = null

    @ManyToMany(fetch = FetchType.EAGER, cascade = [CascadeType.ALL])
    @JoinTable(
        name = "users_roles",
        joinColumns = [JoinColumn(name = "user_id", referencedColumnName = "id")],
        inverseJoinColumns = [JoinColumn(name = "role_id", referencedColumnName = "id")]
    )
    var roles: Collection<Role>? = null

    constructor() {}
    constructor(
        firstName: String?, lastName: String?, email: String?,
        password: String?, roles: Collection<Role>?
    ) : super() {
        this.firstName = firstName
        this.lastName = lastName
        this.email = email
        this.password = password
        this.roles = roles
    }
}
The @Entity annotation specifies that the class is an entity and is mapped to a database table. The @Table annotation specifies the name of the database table to be used for mapping. The @Id annotation specifies the primary key of an entity and the @GeneratedValue provides for the specification of generation strategies for the values of primary keys. The @Column annotation is used to specify the mapped column for a persistent property or field. If no Column annotation is specified, the default value will be applied. We use @ManyToMany annotation to create a many-to-many relationship between two entities. 


Repository Layer[UserRepository.kt]

package com.knf.dev.demo.kotlinspringthymeleafloginsignup.repository

import com.knf.dev.demo.kotlinspringthymeleafloginsignup.model.User
import org.springframework.data.jpa.repository.JpaRepository
import org.springframework.stereotype.Repository

@Repository
interface UserRepository : JpaRepository<User?, Long?> {
    fun findByEmail(email: String?): User?
}
Spring @Repository annotation is used to indicate that the class provides the mechanism for storage, retrieval, search, update and delete operation on objects. JpaRepository is a JPA specific extension of Repository. It contains API for basic CRUD operations and also API for pagination and sorting.


Service layer[UserService]

package com.knf.dev.demo.kotlinspringthymeleafloginsignup.service

import org.springframework.security.core.userdetails.UserDetailsService
import com.knf.dev.demo.kotlinspringthymeleafloginsignup.dto.UserRegistrationDto
import com.knf.dev.demo.kotlinspringthymeleafloginsignup.model.User

interface UserService : UserDetailsService {
    fun save(registrationDto: UserRegistrationDto?): User?
    val all: List<User?>?
}
The UserDetailsService interface is used to retrieve user-related data. It has one method named loadUserByUsername().


Implementation[UserServiceImpl.kt]

package com.knf.dev.demo.kotlinspringthymeleafloginsignup.service

import com.knf.dev.demo.kotlinspringthymeleafloginsignup.dto.UserRegistrationDto
import com.knf.dev.demo.kotlinspringthymeleafloginsignup.model.Role
import com.knf.dev.demo.kotlinspringthymeleafloginsignup.model.User
import com.knf.dev.demo.kotlinspringthymeleafloginsignup.repository.UserRepository
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.security.core.GrantedAuthority
import org.springframework.security.core.authority.SimpleGrantedAuthority
import org.springframework.security.core.userdetails.UserDetails
import org.springframework.security.core.userdetails.UsernameNotFoundException
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder
import org.springframework.stereotype.Service
import java.util.*
import java.util.function.Function
import java.util.stream.Collectors


@Service
class UserServiceImpl(private val userRepository: UserRepository) : UserService {
    @Autowired
    private val passwordEncoder: BCryptPasswordEncoder? = null
    override fun save(registrationDto: UserRegistrationDto?): User? {
        val user = User(
            registrationDto!!.firstName,
            registrationDto.lastName, registrationDto.email,
            passwordEncoder!!.encode(registrationDto.password),
            Arrays.asList(Role("ROLE_USER"))
        )
        return userRepository.save(user)
    }

    @Throws(UsernameNotFoundException::class)
    override fun loadUserByUsername(username: String): UserDetails {
        val user = userRepository.findByEmail(username)
            ?: throw UsernameNotFoundException("Invalid username or password.")
        return org.springframework.security.core.userdetails.User(
            user.email, user.password,
            mapRolesToAuthorities(user.roles!!)
        )
    }

    private fun mapRolesToAuthorities(roles: Collection<Role>): Collection<GrantedAuthority?> {
        return roles.stream().map(Function<Role, SimpleGrantedAuthority?> { role: Role ->
            SimpleGrantedAuthority(
                role.name
            )
        }).collect(Collectors.toList())
    }

    override val all: List<User?>?
        get() = userRepository.findAll()

}


Data Transfer Object[UserRegistrationDto.kt]

package com.knf.dev.demo.kotlinspringthymeleafloginsignup.dto

class UserRegistrationDto {
    var firstName: String? = null
    var lastName: String? = null
    var email: String? = null
    var password: String? = null

    constructor() {}
    constructor(
        firstName: String?,
        lastName: String?, email: String?, password: String?
    ) : super() {
        this.firstName = firstName
        this.lastName = lastName
        this.email = email
        this.password = password
    }
}


Security Configuration[SecurityConfiguration.kt]

package com.knf.dev.demo.kotlinspringthymeleafloginsignup.config

import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter
import org.springframework.beans.factory.annotation.Autowired
import com.knf.dev.demo.kotlinspringthymeleafloginsignup.service.UserService
import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder
import org.springframework.security.authentication.dao.DaoAuthenticationProvider
import kotlin.Throws
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder
import org.springframework.security.config.annotation.web.builders.HttpSecurity
import org.springframework.security.web.util.matcher.AntPathRequestMatcher
import java.lang.Exception

@Configuration
@EnableWebSecurity
class SecurityConfiguration : WebSecurityConfigurerAdapter() {
    @Autowired
    private val userService: UserService? = null
    @Bean
    fun passwordEncoder(): BCryptPasswordEncoder {
        return BCryptPasswordEncoder()
    }

    @Bean
    fun authenticationProvider(): DaoAuthenticationProvider {
        val auth = DaoAuthenticationProvider()
        auth.setUserDetailsService(userService)
        auth.setPasswordEncoder(passwordEncoder())
        return auth
    }

    @Throws(Exception::class)
    override fun configure(auth: AuthenticationManagerBuilder) {
        auth.authenticationProvider(authenticationProvider())
    }

    @Throws(Exception::class)
    override fun configure(http: HttpSecurity) {
        http.authorizeRequests().antMatchers(
            "/registration**", "/js/**",
            "/css/**", "/img/**"
        ).permitAll().anyRequest()
            .authenticated().and().formLogin().loginPage("/login").permitAll().and().logout()
            .invalidateHttpSession(true).clearAuthentication(true)
            .logoutRequestMatcher(AntPathRequestMatcher("/logout")).logoutSuccessUrl("/login?logout")
            .permitAll()
    }
}


Controller[HomeController.kt]

package com.knf.dev.demo.kotlinspringthymeleafloginsignup.controller

import org.springframework.stereotype.Controller
import org.springframework.web.bind.annotation.GetMapping

@Controller
class HomeController {
    @GetMapping("/login")
    fun login(): String {
        return "login"
    }

    @GetMapping("/")
    fun home(): String {
        return "index"
    }
}


Controller[RegistrationController.kt]

package com.knf.dev.demo.kotlinspringthymeleafloginsignup.controller

import org.springframework.web.bind.annotation.RequestMapping
import com.knf.dev.demo.kotlinspringthymeleafloginsignup.service.UserService
import org.springframework.web.bind.annotation.ModelAttribute
import com.knf.dev.demo.kotlinspringthymeleafloginsignup.dto.UserRegistrationDto
import org.springframework.stereotype.Controller
import org.springframework.web.bind.annotation.GetMapping
import org.springframework.web.bind.annotation.PostMapping

@Controller
@RequestMapping("/registration")
class RegistrationController(private val userService: UserService) {
    @ModelAttribute("user")
    fun userRegistrationDto(): UserRegistrationDto {
        return UserRegistrationDto()
    }

    @GetMapping
    fun showRegistrationForm(): String {
        return "registration"
    }

    @PostMapping
    fun registerUserAccount(@ModelAttribute("user") registrationDto: UserRegistrationDto?): String {
        userService.save(registrationDto)
        return "redirect:/registration?success"
    }
}


Spring Boot Main Driver

package com.knf.dev.demo.kotlinspringthymeleafloginsignup

import org.springframework.boot.SpringApplication
import org.springframework.boot.autoconfigure.SpringBootApplication

@SpringBootApplication
class KotlinSpringThymeleafLoginSignupApplication {
    companion object {
        @JvmStatic
        fun main(args: Array<String>) {
   SpringApplication.run(KotlinSpringThymeleafLoginSignupApplication::class.java, *args)
        }
    }
}


View Layer

index.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org" xmlns:sec="http://www.thymeleaf.
             org/thymeleaf-extras-springsecurity3">

<head>
    <meta charset="ISO-8859-1">
    <title>Spring Security Demo</title>

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">

</head>
<style>
    .navbar {
        background-color: green;
    }
</style>

<body>
<!-- create navigation bar ( header) -->
<nav class="navbar navbar-inverse navbar-fixed-top">
    <div class="container">
        <div class="navbar-header">
            <button type="button" class="navbar-toggle collapsed"
                    data-toggle="collapse" data-target="#navbar"
                    aria-expanded="false" aria-controls="navbar">
                <span class="sr-only">Toggle navigation</span>
                <span class="icon-bar"></span> <span
                    class="icon-bar"></span> <span class="icon-bar"></span>
            </button>
            <a class="navbar-brand" href="#" th:href="@{/}">
                Registration and
                Login</a>
        </div>
        <div id="navbar" class="collapse navbar-collapse">
            <ul class="nav navbar-nav">
                <li sec:authorize="isAuthenticated()">
                    <a th:href="@{/logout}">Logout</a></li>
            </ul>
        </div>
    </div>
</nav>

<br><br><br><br>
<div class="container">
    <div class="alert alert-success">
        <strong>Success!</strong> Login Successful.
    </div>
</div>
</body>
</html>


login.html

<!DOCTYPE html>
<html>

<head>
    <meta charset="ISO-8859-1">
    <title>Spring Security Demo</title>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">

</head>
<style>
    .navbar {
        background-color: green;
    }
</style>

<body>

<!-- create navigation bar ( header) -->
<nav class="navbar navbar-inverse navbar-fixed-top">
    <div class="container">
        <div class="navbar-header">
            <button type="button" class="navbar-toggle collapsed"
                    data-toggle="collapse" data-target="#navbar"
                    aria-expanded="false" aria-controls="navbar">
                <span class="sr-only">Toggle navigation</span>
                <span class="icon-bar"></span> <span
                    class="icon-bar"></span> <span class="icon-bar"></span>
            </button>
            <a class="navbar-brand" href="#" th:href="@{/}">
                Registration and
                Login</a>
        </div>
    </div>
</nav>

<br><br><br><br><br><br><br>
<div class="container">
    <div class="row">
        <div class="col-md-6 col-md-offset-3">

            <h1>User Login Page</h1>
            <form th:action="@{/login}" method="post">

                <!-- error message -->
                <div th:if="${param.error}">
                    <div class="alert alert-danger">Invalid username or
                        password.</div>
                </div>

                <!-- logout message -->
                <div th:if="${param.logout}">
                    <div class="alert alert-info">
                        You have been logged out.</div>
                </div>

                <div class="form-group">
                    <label for="username"> Username </label> :
                    <input type="text" class="form-control" id="username"
                           name="username" placeholder="Enter Email ID"
                           autofocus="autofocus">
                </div>

                <div class="form-group">
                    <label for="password">Password</label>:
                    <input type="password" id="password" name="password"
                           class="form-control" placeholder="Enter Password" />
                </div>

                <div class="form-group">
                    <div class="row">
                        <div class="col-sm-6 col-sm-offset-3">
                            <input type="submit" name="login-submit"
                                   id="login-submit"
                                   class="form-control btn btn-primary"
                                   value="Log In" />
                        </div>
                    </div>
                </div>
            </form>
            <div class="form-group">
                    <span>New user? <a href="/" th:href="@{/registration}">
                Register
                  here</a></span>
            </div>
        </div>
    </div>
</div>
</body>
</html>


registration.html

<!DOCTYPE html>
<html>

<head>
    <meta charset="ISO-8859-1">
    <title>Spring Security Demo</title>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">

</head>
<style>
    .navbar {
        background-color: green;
    }
</style>

<body>

<!-- create navigation bar ( header) -->
<nav class="navbar navbar-inverse navbar-fixed-top">
    <div class="container">
        <div class="navbar-header">
            <button type="button" class="navbar-toggle collapsed"
                    data-toggle="collapse" data-target="#navbar"
                    aria-expanded="false" aria-controls="navbar">
                <span class="sr-only">Toggle navigation</span>
                <span class="icon-bar"></span> <span
                    class="icon-bar"></span> <span class="icon-bar"></span>
            </button>
            <a class="navbar-brand" href="#" th:href="@{/}">
                Registration and
                Login </a>
        </div>
    </div>
</nav>

<br><br><br><br><br><br><br>
<!-- Create HTML registration form -->
<div class="container">
    <div class="row">
        <div class="col-md-6 col-md-offset-3">

            <!-- success message -->
            <div th:if="${param.success}">
                <div class="alert alert-info">You've successfully registered
                    to our awesome app!</div>
            </div>

            <h1>Registration</h1>

            <form th:action="@{/registration}" method="post"
                  th:object="${user}">
                <div class="form-group">
                    <label class="control-label" for="firstName">
                        First Name </label>
                    <input id="firstName" class="form-control"
                           th:field="*{firstName}" required
                           autofocus="autofocus" />
                </div>

                <div class="form-group">
                    <label class="control-label" for="lastName">
                        Last Name </label> <input id="lastName"
                                                  class="form-control" th:field="*{lastName}"
                                                  required autofocus="autofocus" />
                </div>

                <div class="form-group">
                    <label class="control-label" for="email"> Email
                    </label> <input id="email" class="form-control"
                                    th:field="*{email}" required autofocus="autofocus"
                />
                </div>

                <div class="form-group">
                    <label class="control-label" for="password">
                        Password </label> <input id="password"
                                                 class="form-control" type="password"
                                                 th:field="*{password}" required
                                                 autofocus="autofocus" />
                </div>

                <div class="form-group">
                    <button type="submit" class="btn btn-primary">
                        Register</button>
                    <span>Already registered? <a href="/"
                                                 th:href="@{/login}">Login
                                here</a></span>
                </div>
            </form>
        </div>
    </div>
</div>
</body>

</html>


Demo 

Start the Spring Boot web app: mvn spring-boot:run



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ReactJS, Spring Boot JWT Authentication Example

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In this tutorial, we’ll create a user registration & login example using ReactJS, Spring Boot, Spring Security, and JWT authentication. You could download the source code from our Github repository, the download link is provided at the end of this tutorial. Technologies used Backend Technologies: Java 17 Spring Boot 2.7.0 Spring Security Spring Data JPA JWT H2 Database Frontend Technologies: React 17.0.1 Axios 0.27.2 Redux 4.0.5 Bootstrap 4.5.2 ReactJS - SpringBoot - JWT - Flow Backend Project Directory: Frontend Project Directory: Following is the screenshot of our application - User Registration: User Signin: Profile View: Access Resource: We will build two projects:  1. Backend:   spring-boot-security-jwt 2. Frontend: react-redux-jwt Project 1: spring-boot-security-jwt Pom.xml <?xml version = "1.0" encoding = "UTF-8" ?> <project xmlns = "http://maven.apache.org/POM/4.0.0" xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
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Spring Boot + Mockito simple application with 100% code coverage

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In this article, we will show you a simple  Spring Boot example to demonstrate test methods for Controllers, Service, and Repository, And code coverage analysis using the EclEmma plugin. Technologies used: Spring Boot 2.6.4 Mockito 3.11.2 Maven 3+ EclEmma plugin Junit 5 Java 17 A quick overview of  Spring Boot, Mockito, and EclEmma plugin Spring boot: Spring boot to develop REST web services and microservices. Spring Boot has taken the Spring framework to the next level. It has drastically reduced the configuration and setup time required for spring projects. We can set up a project with almost zero configuration and start building the things that actually matter to your application. Mockito: Mockito is a mocking framework, a JAVA-predicated library that is utilized for efficacious unit testing of JAVA applications. Mockito is utilized to mock interfaces so that a dummy functionality can be integrated into a mock interface that can be utilized in unit testing. EclEmma : E
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Top 5 Java ORM tools - 2024

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  The term ORM refers to object-relational mapping, which uses objects to adapt programming languages to database systems while allowing them to function with SQL and object-oriented programming ideas. Any kind of database management system that can accomplish object mapping to the table in the virtual system is suitable for the implementation of ORM. Java has a wide variety of ORM tools, some of which are mentioned below: 1. Hibernate Hibernate is a lightweight, open-source, non-invasive Java ORM (Object-Relational Mapping) framework that allows developers to create objects that function independently of database software and create persistence logic in any Java or JavaEE application. It offers an abstraction layer, so developers don't have to bother about implementations; Hibernate handles these tasks internally, such as connecting to databases and creating queries to carry out CRUD operations, among other things. Persistence logic development is done with it. Persistence logic r
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Java - Blowfish Encryption and decryption Example

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Blowfish is an encryption method developed by Bruce Schneier in 1993 as an alternative to the DES encryption method. It is significantly faster than DES and provides good encryption speed, although no effective cryptanalysis technique has been found to date. It is one of the first secure block ciphers that is not protected by any patents and is therefore freely available for anyone to use. This is a symmetric block cipher algorithm. Block size: 64 bits Key size: variable size from 32 to 448 bits number of subsections: 18 [P-array] number of rounds: 16 number of substitution blocks: 4 [each with 512 records of 32 bits each] develop  Example 1: Encryption and decryption using Blowfish import java.io.UnsupportedEncodingException; import java.nio.charset.Charset; import java.security.InvalidKeyException; import java.security.NoSuchAlgorithmException; import java.util.Base64; import javax.crypto.BadPaddingException; import javax.crypto.Cipher; import javax.crypto.IllegalBlockSizeExc
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Spring boot video streaming example-HTML5

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Hello everyone, Today we will learn how to stream MP4 video using Spring Boot and Spring Web Flux.  The Source code download link is provided at the end of this post. New, Quarkus Practice User Interface   Project Structure: G radle(build.gradle) plugins { id 'org.springframework.boot' version '2.5.4' id 'io.spring.dependency-management' version '1.0.11.RELEASE' id 'java' } group = 'com.knf.demo' version = '0.0.1-SNAPSHOT' sourceCompatibility = '11' repositories { mavenCentral() } dependencies { implementation 'org.springframework.boot:spring-boot-starter-webflux' testImplementation 'org.springframework.boot:spring-boot-starter-test' testImplementation 'io.projectreactor:reactor-test' } test { useJUnitPlatform() } Service (VideoStreamingService.java) package  com.knf.demo.service ; import org.springframework.beans.factory.annotation. Autowired ; import org.springframew
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Google Cloud Storage + Spring Boot - File Upload, Download, and Delete

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In this section, we will learn  how to  create a simple spring boot application to perform different file operations such as upload, download, list, and delete files from the Google Cloud Storage. 1.  A little bit of Background Google Cloud Storage Cloud Storage is a managed service for storing unstructured data. Store any amount of data and retrieve it as often as you like. More Info - click here! Spring Boot Spring Boot makes it easy to create stand-alone, production-grade Spring-based Applications that you can "just run".  More Info - click here! 2. Create a GCP Project First, Sign into the Google console at  https://console.cloud.google.com . You can create a new project by first selecting the project dropdown in the top left and selecting " New Project ". Next, specify your GCP  Project name  and  Project ID . Then  Click on the " CREATE " button. Copy " Project ID " and keep it for future purposes. 3. Create a Google Cloud Storage bucket Fr
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