Java Spring Boot (Part 1)
Neil Haddley • April 6, 2021
Spring based Java Applications that you can just run.
Spring Tool Suite
Spring Tool Suite is an Integrated Development Environment based on Eclipse.
Maven
Maven is a build and dependency management tool for Java.
The pom.xml file is used to maintain a list of modules that the Spring application depends on.
Module jar files are downloaded from a managed repository.
Creating a REST project using Spring Boot
Open Spring Tool Suite
Create new Spring Starter Project
Add Book class
Add BooksRestController
Run as Spring Boot App
Test using Browser
Create new Spring Starter Project
Enter the project name and package details
The REST API project depends on "Spring Web"
Add a new class
Add class "Book"
Add class "BooksRestController"
Annotations
The @RestController annotation is used to mark the BooksRestController class as a Spring Framework RestController.
Add @RestController annotation to BooksRestController classUse CTRL+Space to import org.springframework.web.bind.annotation.RestController
Add "books" ArrayList to the BooksRestController
Books REST Controller
The @GetMapping annotation is used to mark the book and books methods as HTTP Get method handlers.
The completed BooksRestController code is shown below.
Run as Spring Boot App
http://localhost:8080/books
http://localhost:8080/books/1788395549
http://localhost:8080/books/1234567890
React client
Static files can be added to the /src/main/resources/static folder of the Spring Boot project.
The static files can be image files, html files and javascript files.
The static files can be a React app that calls the REST API exposed by the (same) Spring Boot project.
Static files
Running the React/Spring Boot app
Book.java
TEXT
1package com.haddley.Books; 2 3public class Book { 4 5 public Book(long id, String title) { 6 _id = id; 7 _title = title; 8 } 9 10 private long _id; 11 12 public long getId() { 13 return _id; 14 } 15 16 public void setId(long id) { 17 this._id = id; 18 } 19 20 public String getTitle() { 21 return _title; 22 } 23 24 public void setTitle(String title) { 25 this._title = title; 26 } 27 28 private String _title; 29 30}
BooksRestController.java
TEXT
1package com.haddley.Books; 2 3import java.util.ArrayList; 4 5import org.springframework.http.HttpStatus; 6import org.springframework.web.bind.annotation.GetMapping; 7import org.springframework.web.bind.annotation.PathVariable; 8import org.springframework.web.bind.annotation.RestController; 9import org.springframework.web.server.ResponseStatusException; 10 11 12@RestController 13public class BooksRestController { 14 15 private static ArrayList<Book> books = new ArrayList<Book>(); 16 17 static { 18 books.add(new Book(1788395549, "Learning Node.js Development")); 19 books.add(new Book(1788620216, "Hands-On Microservices with Node.js")); 20 } 21 22 @GetMapping("/books/{id}") 23 public Book book(@PathVariable Long id) { 24 @SuppressWarnings("unchecked") 25 ArrayList<Book> result = (ArrayList<Book>) BooksRestController.books.clone(); 26 result.removeIf(n -> (n.getId() != id)); 27 if (result.isEmpty()){ 28 throw new ResponseStatusException(HttpStatus.NOT_FOUND, "Book Not Found"); 29 } 30 return result.get(0); 31 } 32 33 @GetMapping("/books") 34 public ArrayList<Book> books() { 35 return BooksRestController.books; 36 } 37 38}
App.js
TEXT
1import React, { useEffect, useState } from 'react'; 2 3function App() { 4 5 const [books, setBooks] = useState([]); 6 7 useEffect(() => { 8 9 console.log("use effect"); 10 fetch('/books') 11 .then( 12 (d) => { 13 d.json().then((b) => { 14 setBooks(() => b) 15 }); 16 } 17 ) 18 19 } 20 , []) 21 22 return ( 23 24 <> 25 {books.map(book => 26 <h4>{book.title}</h4>)} 27 </> 28 29 ); 30} 31 32export default App;
index.html
HTML
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