Prerequisites
Before we start, ensure you have the following:
- Java Development Kit (JDK) installed
- Apache Maven installed
- Node.js and npm installed
- Angular CLI installed (
npm install -g @angular/cli
) - An IDE (such as IntelliJ IDEA, Eclipse, or VS Code) installed
Step 1: Setting Up the Spring Boot Backend
1.1 Create a Spring Boot Project
-
Open Spring Initializr:
- Go to Spring Initializr in your web browser.
-
Configure Project Metadata:
- Project: Maven Project
- Language: Java
- Spring Boot: Select the latest version of Spring Boot 3.3
- Group: com.example
- Artifact: hello-world
- Name: hello-world
- Description: Hello World Service
- Package Name: com.example.helloworld
- Packaging: Jar
- Java Version: 17 (or your preferred version)
- Click
Next
.
-
Select Dependencies:
- On the
Dependencies
screen, select:- Spring Web
- Click
Next
.
- On the
-
Generate the Project:
- Click
Generate
to download the project zip file. - Extract the zip file to your desired location.
- Click
-
Open the Project in Your IDE:
- Open your IDE and import the project as a Maven project.
1.2 Update application.properties
Open the application.properties
file located in the src/main/resources
directory and add the following configuration:
server.port=8080
Explanation:
- Configures the server port to 8080.
1.3 Create HelloWorldController
Create a HelloWorldController
class in the com.example.helloworld.controller
package:
package com.example.helloworld.controller;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@CrossOrigin(origins = "http://localhost:4200")
@RestController
@RequestMapping("/api")
public class HelloWorldController {
@GetMapping("/hello")
public String sayHello() {
return "Hello, World!";
}
}
Explanation:
@CrossOrigin(origins = "http://localhost:4200")
: Enables CORS for requests from the Angular frontend running onlocalhost:4200
.@RestController
: Marks the class as a REST controller.@RequestMapping("/api")
: Maps requests to/api
.sayHello()
: Handles GET requests to/api/hello
and returns "Hello, World!".
1.4 Run the Spring Boot Application
Run the application by executing the HelloWorldApplication
class. The backend should be up and running on http://localhost:8080
.
Step 2: Setting Up the Angular Frontend
2.1 Create an Angular Project
- Open a terminal and run the following command to create a new Angular project:
ng new hello-world-client
- Navigate to the project directory:
cd hello-world-client
2.2 Install Dependencies
Install Bootstrap for styling:
npm install bootstrap
Add Bootstrap to angular.json
:
"styles": [
"src/styles.css",
"node_modules/bootstrap/dist/css/bootstrap.min.css"
],
2.3 Create HelloWorldService
Generate the HelloWorldService:
ng generate service services/hello-world
Edit hello-world.service.ts
:
import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs';
@Injectable({
providedIn: 'root'
})
export class HelloWorldService {
private baseUrl = 'http://localhost:8080/api/hello';
constructor(private http: HttpClient) { }
getHelloWorld(): Observable<string> {
return this.http.get(this.baseUrl, { responseType: 'text' });
}
}
Explanation:
@Injectable({ providedIn: 'root' })
: Marks the service as injectable and available throughout the app.HttpClient
: Service for making HTTP requests.getHelloWorld()
: Sends a GET request to the backend and returns a string.
2.4 Create HelloWorldComponent
Generate the HelloWorldComponent:
ng generate component components/hello-world
Edit hello-world.component.ts
:
import { Component, OnInit } from '@angular/core';
import { HelloWorldService } from '../../services/hello-world.service';
@Component({
selector: 'app-hello-world',
templateUrl: './hello-world.component.html',
styleUrls: ['./hello-world.component.css']
})
export class HelloWorldComponent implements OnInit {
message: string = '';
constructor(private helloWorldService: HelloWorldService) { }
ngOnInit(): void {
this.helloWorldService.getHelloWorld().subscribe(data => {
this.message = data;
});
}
}
Edit hello-world.component.html
:
<div class="container mt-5">
<div class="row justify-content-center">
<div class="col-md-6">
<div class="card">
<div class="card-header">Hello World</div>
<div class="card-body">
<p>{{ message }}</p>
</div>
</div>
</div>
</div>
</div>
Explanation:
HelloWorldComponent
retrieves the "Hello, World!" message from the backend and displays it.
2.5 Update Angular Routing
Edit app-routing.module.ts
:
import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
import { HelloWorldComponent } from './components/hello-world/hello-world.component';
const routes: Routes = [
{ path: 'hello', component: HelloWorldComponent },
{ path: '', redirectTo: '/hello', pathMatch: 'full' }
];
@NgModule({
imports: [RouterModule.forRoot(routes)],
exports: [RouterModule]
})
export class AppRoutingModule { }
Explanation:
- Defines a route for the
HelloWorldComponent
. - Redirects the root path to
/hello
.
2.6 Update Angular App Module
Edit app.module.ts
:
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { HttpClientModule } from '@angular/common/http';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { HelloWorldComponent } from './components/hello-world/hello-world.component';
@NgModule({
declarations: [
AppComponent,
HelloWorldComponent
],
imports: [
BrowserModule,
AppRoutingModule,
HttpClientModule
],
providers: [],
bootstrap: [AppComponent]
})
export class AppModule { }
Explanation:
- Imports necessary modules for the Angular app.
- Declares the components used in the app.
- Sets up the app's root module.
2.7 Run the Angular Application
Open a terminal in the Angular project directory and run the application:
ng serve
Visit http://localhost:4200
in your web browser to see the application.
Conclusion
In this tutorial, we created a simple "Hello World" application using Spring Boot 3 for the backend and Angular 18 for the frontend. We handled CORS issues to ensure smooth communication between the Angular frontend and the Spring Boot backend. By following this structure, you can extend and customize the application as needed.
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