Angular + Kotlin +Spring Boot + Mongo DB CRUD Example

Hello everyone, today we will learn how to develop a full-stack web application that is a basic User Management Application using Angular 10, Kotlin, Spring Boot, and MongoDB.You can download the source code from our GitHub Repository.



After completing this tutorial what we will build? 

We will build a full-stack web application that is a basic User Management Application with CRUD features: 

• Create User 
• List User 
• Update User 
• Delete User 

Following is the screenshot of our application -



A quick overview of Angular 10, Kotlin, Spring Boot, and MongoDB 

Kotlin

Kotlin is a statically typed, general-purpose programming language targeting the Java platform. Kotlin is concise, safe, pragmatic, and fixated on interoperability with Java code. It can be used virtually everywhere Java is utilized today: for server-side development, Android apps, and much more. Kotlin works great with all subsisting Java libraries and frameworks and runs with the same level of performance as Java.

MongoDB

MongoDB is a document database built on a scale-out architecture that has to propagate with developers of all kinds who are building scalable applications utilizing agile methodologies.

MongoDB was built for people who are building internet and business applications who need to evolve expeditiously and scale elegantly. If you are doing that, you should consider MongoDB.

Companies and development teams of all sizes use MongoDB because:
  • The document data model is a potent way to store and retrieve data that sanctions developers to move expeditiously.
  • MongoDB’s horizontal, scale-out architecture can fortify astronomically immense volumes of both data and traffic.
  • MongoDB has a great utilizer experience for developers who can install MongoDB and commence inscribing code immediately.

Angular

Angular is a TypeScript-predicated open-source web application framework led by the Angular Team at Google and by a community of individuals and corporations. Angular is a consummate re-indite from the same team that built AngularJS.

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.

We divided this tutorial into two parts

PART 1 - Restful API Development with Kotlin + Spring Boot (back end)
PART 2 - UI development using Angular 10 (front end/client)



PART 1 - Restful API Development with Kotlin + Spring Boot 

These are APIs that Spring backend App will export:



Backend project structure:




pom.xml[Maven]

Include spring-boot-starter-web for Spring MVC and REST structure, and spring-boot-starter-data-mongodb for CRUD repository.
<?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>2.3.7.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.knf.dev</groupId>
    <artifactId>springboot-kotlin-crud</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot-kotlin-crud</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <kotlin.version>1.3.72</kotlin.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-mongodb</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</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>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </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>
                    </compilerPlugins>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-allopen</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                </dependencies>
            </plugin>
        </plugins>
    </build>
</project> 



Creating the Document

import org.bson.types.ObjectId
import org.springframework.data.annotation.Id
import org.springframework.data.mongodb.core.mapping.Document
import org.springframework.web.bind.annotation.CrossOrigin

@Document(collection = "users")
data class User(
        @Id
        var id: String? = ObjectId().toHexString(),
        val firstName: String,
        val lastName: String,
        val emailId: String
)



Creating the Repository

Let’s now create the repository for accessing the data from the database.
package com.knf.dev.repository

import com.knf.dev.model.User
import org.springframework.data.mongodb.repository.MongoRepository
import org.springframework.stereotype.Repository

@Repository
interface UserRepository : MongoRepository<User, String>



Creating the controller End-points

package com.knf.dev.controller

import com.knf.dev.model.User
import com.knf.dev.repository.UserRepository
import org.springframework.http.HttpStatus
import org.springframework.http.ResponseEntity
import org.springframework.web.bind.annotation.*
import java.util.*

@RestController
@RequestMapping("/api/v1/")
@CrossOrigin(origins = arrayOf("http://localhost:4200"))
class UserController(private val userRepository: UserRepository) {

    @GetMapping("/users")
    fun getAllUsers(): List<User> =
            userRepository.findAll()

    @PostMapping("/users")
    fun createNewUser(@RequestBody user: User): User =
            userRepository.save(user)

    @GetMapping("/users/{id}")
    fun getUserById(@PathVariable(value = "id") userId: String): 
                                ResponseEntity<User> {
        return userRepository.findById(userId).map { user ->
            ResponseEntity.ok(user)
        }.orElse(ResponseEntity.notFound().build())
    }

    @PutMapping("/users/{id}")
    fun updateUserById(@PathVariable(value = "id") userId: String,
                       @RequestBody newUser: User): ResponseEntity<User> {

        return userRepository.findById(userId).map { existingUser ->
            val updatedUser: User = existingUser
                    .copy(firstName = newUser.firstName, lastName = 
                          newUser.lastName, emailId = newUser.emailId)
            ResponseEntity.ok().body(userRepository.save(updatedUser))
        }.orElse(ResponseEntity.notFound().build())

    }

    @DeleteMapping("/users/{id}")
    fun deleteUserById(@PathVariable(value = "id") userId: String): 
                            ResponseEntity<Void> {
        return userRepository.findById(userId).map { user ->
            userRepository.delete(user)
            ResponseEntity<Void>(HttpStatus.OK)
        }.orElse(ResponseEntity.notFound().build())

    }
}



Spring Boot Main Driver

package com.knf.dev

import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication

@SpringBootApplication
class SpringbootKotlinCrudApplication

fun main(args: Array<String>) {
    runApplication<SpringbootKotlinCrudApplication>(*args)
}


PART 2 - UI development using Angular

Project Structure:




package.json

A package.json is a JSON file that subsists at the root of a Javascript/Node project. It holds metadata pertinent to the project and is utilized for managing the project's dependencies, scripts, version, and a whole lot more.
{
  "name": "front-end-simple-crud",
  "version": "0.0.0",
  "scripts": {
    "ng": "ng",
    "start": "ng serve",
    "build": "ng build",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e"
  },
  "private": true,
  "dependencies": {
    "@angular/animations": "~10.1.2",
    "@angular/common": "~10.1.2",
    "@angular/compiler": "~10.1.2",
    "@angular/core": "~10.1.2",
    "@angular/forms": "~10.1.2",
    "@angular/platform-browser": "~10.1.2",
    "@angular/platform-browser-dynamic": "~10.1.2",
    "@angular/router": "~10.1.2",
    "bootstrap": "^4.5.3",
    "jquery": "^3.5.1",
    "rxjs": "~6.6.0",
    "tslib": "^2.0.0",
    "zone.js": "~0.10.2"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "^0.1100.3",
    "@angular/cli": "~10.1.2",
    "@angular/compiler-cli": "~10.1.2",
    "@types/jasmine": "~3.5.0",
    "@types/jasminewd2": "~2.0.3",
    "@types/node": "^12.11.1",
    "codelyzer": "^6.0.0",
    "jasmine-core": "~3.6.0",
    "jasmine-spec-reporter": "~5.0.0",
    "karma": "~5.0.0",
    "karma-chrome-launcher": "~3.1.0",
    "karma-coverage-istanbul-reporter": "~3.0.2",
    "karma-jasmine": "~4.0.0",
    "karma-jasmine-html-reporter": "^1.5.0",
    "protractor": "~7.0.0",
    "ts-node": "~8.3.0",
    "tslint": "~6.1.0",
    "typescript": "~4.0.2"
  }
}



The User.ts file(User Model)

Path - src/app/user.ts 
Before defining the UserListComponent, let’s define a User class for working with users. create a new file user.ts inside src/app folder and add the following code to it -
export class User {
    _id: string;
    firstName: string;
    lastName: string;
    emailId: string;
    active: boolean;

}



Create User List Template and Component

User List Component

Path - src/app/user-list/user-list.component.ts
Let's create the UserListComponent component, which will display a list of users, create a new user, and delete a user.
import { UserDetailsComponent } from '../user-details/user-details.component';
import { Observable } from "rxjs";
import { UserService } from "../user.service";
import { User } from "../user";
import { Component, OnInit } from "@angular/core";
import { Router } from '@angular/router';

@Component({
  selector: "app-user-list",
  templateUrl: "./user-list.component.html",
  styleUrls: ["./user-list.component.css"]
})
export class UserListComponent implements OnInit {
  users: Observable<User[]>;

  constructor(private userService: UserService,
    private router: Router) { }

  ngOnInit() {
    this.reloadData();
  }

  reloadData() {
    this.users = this.userService.getUsersList();
  }

  deleteUser(_id: string) {
    this.userService.deleteUser(_id)
      .subscribe(
        data => {
          console.log(data);
          this.reloadData();
        },
        error => console.log(error));
  }
  updateUser(id: string) {
    this.router.navigate(['update', id]);
  }
  userDetails(_id: string) {
    this.router.navigate(['details', _id]);
  }
}



User List Template

Path - src/app/user-list/user-list.component.html
Add user-list.component.html file with the following code to it -
<div class="panel panel-primary">
  <div class="panel-heading">
    <h2>User List</h2>
  </div>
  <div class="panel-body">
    <table class="table table-striped">
      <thead>
        <tr>
          <th>Firstname</th>
          <th>Lastname</th>
          <th>Email</th>
          <th>Actions</th>
        </tr>
      </thead>
      <tbody>
        <tr *ngFor="let user of users | async">
          <td>{{user.firstName}}</td>
          <td>{{user.lastName}}</td>
          <td>{{user.emailId}}</td>
          <td>
            <button (click)="updateUser(user.id)" class="btn btn-warning" 
style="margin-left: 10px">Update</button>
            <button (click)="deleteUser(user.id)" class="btn btn-danger" 
style="margin-left: 10px">Delete</button>
            <button (click)="userDetails(user.id)" class="btn btn-info" 
style="margin-left: 10px">Details</button>
          </td>
        </tr>
      </tbody>
    </table>
  </div>
</div>



Create Add User Template and Component

Add User Component

Path - src/app/create-user/create-user.component.ts
CreateUserComponent is used to create and handle new user form data. Add the following code to it -
import { UserService } from '../user.service';
import { User } from '../user';
import { Component, OnInit } from '@angular/core';
import { Router } from '@angular/router';

@Component({
  selector: 'app-create-user',
  templateUrl: './create-user.component.html',
  styleUrls: ['./create-user.component.css']
})
export class CreateUserComponent implements OnInit {

  user: User = new User();
  submitted = false;

  constructor(private userService: UserService,
    private router: Router) { }

  ngOnInit() {
  }

  newUser(): void {
    this.submitted = false;
    this.user = new User();
  }

  save() {
    this.userService
      .createUser(this.user).subscribe(data => {
        console.log(data)
        this.user = new User();
        this.gotoList();
      },
        error => console.log(error));
  }

  onSubmit() {
    this.submitted = true;
    this.save();
  }

  gotoList() {
    this.router.navigate(['/users']);
  }
}



Create a User Template

Path - src/app/create-user/create-user.component.html 
The create-user.component.html shows the add using HTML form. Add the following code to it -
<h3>Create User</h3>
<div [hidden]="submitted" style="width: 400px;">
  <form (ngSubmit)="onSubmit()">
    <div class="form-group">
      <label for="name">First Name</label>
      <input type="text" class="form-control" id="firstName" 
required [(ngModel)]="user.firstName" name="firstName">
    </div>

    <div class="form-group">
      <label for="name">Last Name</label>
      <input type="text" class="form-control" id="lastName" 
required [(ngModel)]="user.lastName" name="lastName">
    </div>

    <div class="form-group">
      <label for="name">Email Id</label>
      <input type="text" class="form-control" id="emailId" 
required [(ngModel)]="user.emailId" name="emailId">
    </div>

    <button type="submit" class="btn btn-danger">Submit</button>
  </form>
</div>

<div [hidden]="!submitted">
  <h4>Successfully submitted!</h4>
</div>



Update User Template and Component

Update User Component

Path - src/app/update-user/update-user.component.ts 
UpdateUserComponent is used to update an existing user.
import { Component, OnInit } from '@angular/core';
import { User } from '../user';
import { ActivatedRoute, Router } from '@angular/router';
import { UserService } from '../user.service';

@Component({
  selector: 'app-update-user',
  templateUrl: './update-user.component.html',
  styleUrls: ['./update-user.component.css']
})
export class UpdateUserComponent implements OnInit {

  _id: string;
  user: User;

  constructor(private route: ActivatedRoute, private router: Router,
    private userService: UserService) { }

  ngOnInit() {
    this.user = new User();

    this._id = this.route.snapshot.params['_id'];

    this.userService.getUser(this._id)
      .subscribe(data => {
        this.user = data;
      }, error => console.log(error));
  }

  updateUser() {
    this.userService.updateUser(this._id, this.user)
      .subscribe(data => {
        console.log(data);
        this.user = new User();
        this.gotoList();
      }, error => console.log(error));
  }

  onSubmit() {
    this.updateUser();
  }

  gotoList() {
    this.router.navigate(['/users']);
  }
}



Update User Template

Path - src/app/update-user/update-user.component.html 
The update-user.component.html shows the updated user HTML form. Add the following code to this file -
<h3>Update User</h3>
<div  style="width: 500px;">
  <form (ngSubmit)="onSubmit()">
    <div class="form-group">
      <label for="name">First Name</label>
      <input type="text" class="form-control" id="firstName" 
required [(ngModel)]="user.firstName" name="firstName">
    </div>

    <div class="form-group">
      <label for="name">Last Name</label>
      <input type="text" class="form-control" id="lastName" 
required [(ngModel)]="user.lastName" name="lastName">
    </div>

    <div class="form-group">
      <label for="name">Email Id</label>
      <input type="text" class="form-control" id="emailId" 
required [(ngModel)]="user.emailId" name="emailId">
    </div>

    <button type="submit" class="btn btn-success">Submit</button>
  </form>
</div>



Create a View User Details Template and Component

User Details Component

Path - src/app/user-details/user-details.component.ts 
The UserDetailsComponent component is used to display a particular user detail. Add the following code to it -
import { User } from '../user';
import { Component, OnInit, Input } from '@angular/core';
import { UserService } from '../user.service';
import { Router, ActivatedRoute } from '@angular/router';

@Component({
  selector: 'app-user-details',
  templateUrl: './user-details.component.html',
  styleUrls: ['./user-details.component.css']
})
export class UserDetailsComponent implements OnInit {

  _id: string;
  user: User;

  constructor(private route: ActivatedRoute,private router: Router,
    private userService: UserService) { }

  ngOnInit() {
    this.user = new User();

    this._id = this.route.snapshot.params['_id'];
    console.log("gh"+this._id);
    this.userService.getUser(this._id)
      .subscribe(data => {
        console.log(data)
        this.user = data;
      }, error => console.log(error));
  }

  list(){
    this.router.navigate(['users']);
  }
}



User Details  Template

Path - src/app/user-details/user-details.component.html 
The user-details.component.html displays a particular user detail. Add the following code to it -
<h2>User Details</h2>

<hr />
<div *ngIf="user">
  <div>
    <label><b>First Name: </b></label> {{user.firstName}}
  </div>
  <div>
    <label><b>Last Name: </b></label> {{user.lastName}}
  </div>
  <div>
    <label><b>Email Id: </b></label> {{user.emailId}}
  </div>
</div>

<br>
<br>
<button (click)="list()" class="btn btn-primary">User List</button><br>



User Service

Path - src/app/user.service.ts 
The UserService will be used to get the data from the backend by calling  APIs. Update the user.service.ts file inside src/app directory with the following code to it -
import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs';

@Injectable({
  providedIn: 'root'
})
export class UserService {

  private baseUrl = 'http://localhost:8000/api/v1/users';

  constructor(private http: HttpClient) { }

  getUser(_id: string): Observable<any> {
    return this.http.get(`${this.baseUrl}/${_id}`);
  }

  createUser(user: Object): Observable<Object> {
    return this.http.post(`${this.baseUrl}`, user);
  }

  updateUser(_id: string, value: any): Observable<Object> {
    return this.http.put(`${this.baseUrl}/${_id}`, value);
  }

  deleteUser(_id: string): Observable<any> {
    return this.http.delete(`${this.baseUrl}/${_id}`, 
{ responseType: 'text' });
  }

  getUsersList(): Observable<any> {
    return this.http.get(`${this.baseUrl}`);
  }
}



App Routing Module

Path: /src/app/app.routing.module.ts 
Routing for the Angular app is configured as an array of Routes, each component is mapped to a path so the Angular Router knows which component to display based on the URL in the browser address bar.
import { UserDetailsComponent } from './user-details/user-details.component';
import { CreateUserComponent } from './create-user/create-user.component';
import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import {UserListComponent } from './user-list/user-list.component';
import { UpdateUserComponent } from './update-user/update-user.component';

const routes: Routes = [
  { path: '', redirectTo: 'user', pathMatch: 'full' },
  { path: 'users', component: UserListComponent },
  { path: 'add', component: CreateUserComponent },
  { path: 'update/:_id', component: UpdateUserComponent },
  { path: 'details/:_id', component: UserDetailsComponent },
];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }



App Component

Path: /src/app/app.component.ts 
The app component is the root component of the application, it defines the root tag of the app as with the selector property of the @Component decorator.
import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'Angular 10 + Node.js + Mongo DB CRUD ';
}



App Component Template

Path: /src/app/app.component.html 
Defines the HTML template associated with the root AppComponent.
<nav class="navbar navbar-expand-sm bg-success navbar-dark">
  <!-- Links -->
  <ul class="navbar-nav">
    <li class="nav-item">
        <a routerLink="users" class="nav-link" routerLinkActive="active">
User List</a>
    </li>
    <li class="nav-item">
        <a routerLink="add" class="nav-link" routerLinkActive="active">
Add User</a>
    </li>
  </ul>
</nav>
<div class="container">
  <br>
  <h2 style="text-align: center;">{{title}}</h2>
  <hr>  
  <div class="card">
    <div class="card-body">
  <router-outlet></router-outlet>
    </div>
  </div>
</div>

<footer class="footer">
  <div class="container">
      <span>All Rights Reserved 2020 @Knowledge Factory</span>
  </div>
</footer>



App Module

Path: /src/app/app.module.ts 
Defines the root module, named AppModule, that tells Angular how to assemble the application. Initially declares only the AppComponent. 
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { CreateUserComponent } from './create-user/create-user.component';
import { UserDetailsComponent } from './user-details/user-details.component';
import { UserListComponent } from './user-list/user-list.component';
import { UpdateUserComponent } from './update-user/update-user.component';
import { HttpClientModule } from '@angular/common/http';
@NgModule({
  declarations: [
    AppComponent,
    CreateUserComponent,
    UserDetailsComponent,
    UserListComponent,
    UpdateUserComponent
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    FormsModule,
    HttpClientModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }



index.html

Path: /src/index.html 
The main index.html file is the initial page loaded by the browser that kicks everything off.
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>Angular10CRUD</title>
  <base href="/">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="icon" type="image/x-icon" href="favicon.ico">
</head>
<body>
  <app-root></app-root>
</body>
</html>



Main/Bootstrap File

Path: /src/main.ts
The main file is the entry point used by angular to launch
and bootstrap the application.
import { enableProdMode } from '@angular/core';
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';

import { AppModule } from './app/app.module';
import { environment } from './environments/environment';

if (environment.production) {
  enableProdMode();
}

platformBrowserDynamic().bootstrapModule(AppModule)
  .catch(err => console.error(err));

Local Setup and Run the application

Step 1: Install Mongo DB - Click here


Step 2: Download or clone the source code from GitHub to a local machine - Click here



Backend


Step 3: mvn clean install


Step 4: Run the Spring Boot application - mvn spring-boot:run



Frontend


Step 5: npm install 


Step 6: npm serve

From the browser call the endpoint http://localhost:4200/

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Example 1: Java 8 program to print odd numbers from a List   import java.util.Arrays; import java.util.List; import java.util.stream.Collectors; /*Java 8 Program to find Odd Numbers from a List*/ public class DriverClass { public static void main( String [] args) { List < Integer > numbers = Arrays. asList( 1 , 4 , 8 , 40 , 11 , 22 , 33 , 99 ); List < Integer > oddNumbers = numbers.stream(). filter(o -> o % 2 != 0 ). collect(Collectors.toList()); System.out.println(oddNumbers); } } 1. Initialize List using Arrays.asList() method. Java's built-in Arrays.asList() method converts an array into a list. This method takes an array as an argument and returns a List object. 2.  Java List interface provides stream() method which returns a sequential Stream with list of Integer as its source. 3. The Java stream filter(...
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Java Stream API - How to convert List of objects to another List of objects using Java streams?

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In this section, we will show you how to convert a List of objects to another List of objects in Java using the Java streams map(). The ‘map’ method maps each element to its corresponding result. Java Stream API   The Java Stream API provides a functional programming approach over the object oriented capabilities of Java. It is used for processing collections of objects. The Stream in Java can be defined as a sequence of elements from a source List, Set or Array. Most of the stream operations return a Stream. This avails engender a chain of stream operations(stream pipe-lining). The streams withal support the aggregate or terminal operations on the elements. for example, finding the sum or maximum element or finding the average etc...Stream operations can either be executed sequentially or parallel. when performed parallelly, it is called a parallel stream.   Stream map() Method   The Java 8 Stream map() is an intermediate operation. It converts Stream<obj1> to Str...
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Registration and Login with Spring Boot + Spring Security + Thymeleaf

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In this section, we will learn how to create user registration and login using Spring boot, Spring security, Thymeleaf, JPA, and H2DB. The GitHub repository link is provided at the end of this tutorial. You can download the source code. Technologies used: Spring Boot 2.5.5  Spring Data JPA  Spring Security  Thymeleaf  Maven 3+  Java 17  H2 Database   User Interface User Registration Authentication Failed Authentication success Sign out Final Project Structure: Complete 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" 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-pare...
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Java, Spring Boot Mini Project - Library Management System - Download

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Hello everyone, Hope you are doing well. Here, we provide a Library Management System mini-project for beginners, it's free for download. Maybe you can build more on top of this project and create your own product, that's all about you. The source code download link is provided at the end of this post. 1. Benefit of this project You could cover the following technologies and features by learning and debugging this mini project. Java 17 Java Stream Java Lamda Expressions Java Records Functional programming Object-oriented programming var Keyword in Java Generics in Java Java Switch Spring boot 2.6.4 Spring Security Thymeleaf template engine OpenCSV Spring Data JPA Server Side Pagination H2 Database  Bootstrap HTML CSS and more... 2. Objective Of Spring Boot On Library Management System The main objective of this project is to manage the details of the books, author, category, and publisher. Only Admin/Librarian will manage all these activities. Also, they can export the data in ...
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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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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.IllegalBlockSiz...
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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.springframework...
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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 bucke...
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