Why Use Assert with Spring Validator? A Comparison and Usage Guide

Why Use Assert with Spring Validator?

In short, Validator only solves the data validation of the parameter itself and cannot handle validation between the parameter and business data.

Let's look at an example.

@RestController
@Slf4j
@RequestMapping("/assert")
public class ArtisanController {

    @Autowired
    private ArtisanDao artisanDao;

    /**
     * Validator only solves the data validation of the parameter itself, cannot solve validation between parameter and business data
     */
    @PostMapping("/testNoAssert")
    public void testNoAssert(@RequestParam("artisanId") String artisanId) {
        Artisan artisan = artisanDao.selectArtisanReturnNull(artisanId);
        if (artisan == null) {
            throw new IllegalArgumentException("用户不存在");
        }
    }
}

Non‑null checks are familiar to everyone.

How would this look using Assert?

@PostMapping("/testWithAssert")
public void testWithAssert(@RequestParam("artisanId") String artisanId) {
    Artisan artisan = artisanDao.selectArtisanReturnNull(artisanId);
    Assert.notNull(artisan, "用户不存在（Assert抛出）");
}

Notice that the Assert version is more elegant and concise while achieving the same effect.

Assert assertions basically replace traditional if‑statements, reducing the number of lines needed for business parameter validation and improving code readability – thumbs up!

Everyone uses it; just search and you’ll see many examples.

Return Result

Let's take a look.

The exception thrown is IllegalArgumentException , so it should be handled globally.

@ExceptionHandler({IllegalArgumentException.class, IllegalStateException.class})
@ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
public ResponseData
exception(IllegalArgumentException e) {
    return ResponseData.fail(ResponseCode.ILLEGAL_ARGUMENT.getCode(), e.getMessage());
}

In my case the result is processed by a global exception handler; without it the raw error would be returned.

org.springframework.util.Assert

Let's see what methods Assert provides.

They can be roughly classified as:

Object and Type Assertions

Text Assertions

Logic Assertions

Collection and Map Assertions

Array Assertions

Source Code

https://github.com/yangshangwei/boot2

Thank you for reading, hope it helps :)

Source: artisan.blog.csdn.net/article/details/123105926