Spring Boot Web应用开发是否必须引入Thymeleaf这类模板引擎？

Hey there! Great question—especially since this is your first independent Spring Boot project. Let’s break this down clearly:

The Short Answer #

No, you don’t have to use a template engine like Thymeleaf at all if your backend is focused on sending JSON data to the client.

Here’s Why #

Template engines like Thymeleaf, FreeMarker, or JSP are built for one main job: rendering complete HTML pages on the server by merging your backend data (like what you fetch from PostgreSQL) into pre-written HTML templates. This is the traditional "server-side rendering" approach, where the browser gets a fully built webpage directly from the server.

But if your project uses a JSON-based API pattern (where your backend sends raw JSON data, and the client—whether it’s a React/Vue frontend, mobile app, or even vanilla JavaScript—handles turning that JSON into HTML), template engines are totally irrelevant here. Your Spring Boot app only needs to expose REST endpoints that return JSON, which it can do natively without any extra template dependencies.

How Spring Boot Handles JSON Without Templates #

By default, if you don’t add any template engine dependencies to your pom.xml (Maven) or build.gradle (Gradle), Spring Boot won’t attempt to render HTML. Instead, it uses the Jackson library (included automatically with the spring-boot-starter-web dependency) to serialize your Java objects (like the data you pull from PostgreSQL) into JSON.

Here’s a quick example of how that looks in code:

@RestController
@RequestMapping("/api/items")
public class ItemController {

    private final ItemRepository itemRepository;

    // Constructor injection (Spring Boot 3+ preferred)
    public ItemController(ItemRepository itemRepository) {
        this.itemRepository = itemRepository;
    }

    @GetMapping
    public List<Item> getAllItems() {
        // Fetch data from PostgreSQL directly
        return itemRepository.findAll();
    }
}

This controller will return a JSON array of your Item objects as soon as you hit the /api/items endpoint—no template engine required.

When Would You Need a Template Engine? #

You’d only need to add a template engine if you’re building a server-rendered app, where the server sends fully built HTML pages to the browser (for example, a classic Spring MVC app where you return ModelAndView objects pointing to Thymeleaf templates). But since you’re working with JSON data, this isn’t necessary for your use case.

Final Takeaway #

Feel free to skip adding any template engine dependencies to your project. Your Spring Boot app will work perfectly fine returning JSON to your client, and you can focus on building your REST API and integrating with PostgreSQL. If you run into specific issues with JSON serialization or endpoint setup, just share more details and we can help!

内容的提问来源于stack exchange，提问作者lu_lu