Java Spring Boot (Part 1)
Neil Haddley • April 6, 2021
Spring based Java Applications that you can just run.
I used Spring Tool Suite (an Eclipse-based IDE) and Maven (a Java build and dependency management tool) to create a REST API with Spring Boot.
Creating a REST project using Spring Boot
I opened Spring Tool Suite, created a new Spring Starter Project, added a Book class and a BooksRestController, then ran and tested the app in the browser.
I created a new Spring Starter Project
I entered the project name and package details
The REST API project depends on "Spring Web"
I added a new class
I added class "Book"
I added 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.
I ran it as a Spring Boot App
http://localhost:8080/books
http://localhost:8080/books/1788395549
http://localhost:8080/books/1234567890
React client
I added static files (images, HTML, and JavaScript) to the /src/main/resources/static folder of the Spring Boot project, including 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
JAVA
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
JAVA
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
JAVASCRIPT
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
1<!DOCTYPE html> 2<html lang="en"> 3 4<head> 5 <title>React App</title> 6</head> 7 8<body> 9 10 <noscript>You need to enable JavaScript to run this app.</noscript> 11 <div id="root"></div> 12 13 <script>!function (e) {function r(r) {for (var n, i, l = r[0], p = r[1], f = r[2], c = 0, s = []; c < l.length; c++)i = l[c], Object.prototype.hasOwnProperty.call(o, i) && o[i] && s.push(o[i][0]), o[i] = 0; for (n in p) Object.prototype.hasOwnProperty.call(p, n) && (e[n] = p[n]); for (a && a(r); s.length;)s.shift()(); return u.push.apply(u, f || []), t()} function t() {for (var e, r = 0; r < u.length; r++) {for (var t = u[r], n = !0, l = 1; l < t.length; l++) {var p = t[l]; 0 !== o[p] && (n = !1)} n && (u.splice(r--, 1), e = i(i.s = t[0]))} return e} var n = {}, o = {1: 0}, u = []; function i(r) {if (n[r]) return n[r].exports; var t = n[r] = {i: r, l: !1, exports: {}}; return e[r].call(t.exports, t, t.exports, i), t.l = !0, t.exports} i.m = e, i.c = n, i.d = function (e, r, t) {i.o(e, r) || Object.defineProperty(e, r, {enumerable: !0, get: t})}, i.r = function (e) {"undefined" != typeof Symbol && Symbol.toStringTag && Object.defineProperty(e, Symbol.toStringTag, {value: "Module"}), Object.defineProperty(e, "__esModule", {value: !0})}, i.t = function (e, r) {if (1 & r && (e = i(e)), 8 & r) return e; if (4 & r && "object" == typeof e && e && e.__esModule) return e; var t = Object.create(null); if (i.r(t), Object.defineProperty(t, "default", {enumerable: !0, value: e}), 2 & r && "string" != typeof e) for (var n in e) i.d(t, n, function (r) {return e[r]}.bind(null, n)); return t}, i.n = function (e) {var r = e && e.__esModule ? function () {return e.default} : function () {return e}; return i.d(r, "a", r), r}, i.o = function (e, r) {return Object.prototype.hasOwnProperty.call(e, r)}, i.p = "/"; var l = this["webpackJsonpnode-spring-client"] = this["webpackJsonpnode-spring-client"] || [], p = l.push.bind(l); l.push = r, l = l.slice(); for (var f = 0; f < l.length; f++)r(l[f]); var a = p; t()}([])</script> 14 <script src="/js/2.bd91be3c.chunk.js"></script> 15 <script src="/js/main.d36b6e09.chunk.js"></script> 16 17</body> 18 19</html>