Spring Boot Rest 中没有内容 [英] No Content in Spring Boot Rest

问题描述

如何配置 Spring Boot 在 GET 方法(通常是 findAll 方法)中不获取记录时返回 204?我不想在每种方法中都做处理，输入下面的代码:

How do I configure Spring Boot to return 204 in GET methods (typically findAll methods) when the method does not fetch records? I would not like to do treatment in each method, type the code below:

if(!result)
    return new ResponseEntity<Void>(HttpStatus.NO_CONTENT);
    return new ResponseEntity<Void>(HttpStatus.OK)

我想转换这个方法:

@GetMapping
public ResponseEntity<?> findAll(){
    List<User> result = service.findAll();
    return !result.isEmpty() ? 
            new ResponseEntity<>(result, HttpStatus.OK) : new ResponseEntity<Void>(HttpStatus.NO_CONTENT);
}

在这个:

@GetMapping
public List<User> findAll(){
    return service.findAll();
}

如果 findAll() 的结果为空或 null，那么我的控制器应该返回 204 而不是 200.

If the result from findAll() is empty or null then my controller should return 204 instead of 200.

推荐答案

你可以注册一个自定义的 ResponseBodyAdvice 允许自定义 @ResponseBody 或 ResponseEntity 处理程序方法(就在内容被 MessageConverter 序列化之前):

You could register a custom ResponseBodyAdvice which allows customizing the response of @ResponseBody or ResponseEntity handler methods (right before the content is being serialized by a MessageConverter):

@ControllerAdvice
class NoContentControllerAdvice implements ResponseBodyAdvice<List<?>> {

    @Override
    public boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) {
        return List.class.isAssignableFrom(returnType.getParameterType());
    }

    @Override
    public List<?> beforeBodyWrite(List<?> body, MethodParameter returnType, MediaType selectedContentType,
               Class<? extends HttpMessageConverter<?>> selectedConverterType,
               ServerHttpRequest request, ServerHttpResponse response) {

        if (body.isEmpty()) {
            response.setStatusCode(HttpStatus.NO_CONTENT);
        }
        return body;
    }
}

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