有很多方法!
使用@ResponseBody：

@ResponseBody
@ExceptionHandler(EntityNotFoundException.class)
protected ProblemDetail handleEntityNotFoundException(EntityNotFoundException ex, 
                                                      HttpServletRequest request) {
    ProblemDetail problemDetail = forStatusAndDetail(NOT_FOUND, ex.getMessage());
    problemDetail.setTitle("entity.not.found");
    return problemDetail;
}

使用SpringResponseEntitystatic模式：

@ExceptionHandler(EntityNotFoundException.class)
protected ResponseEntity<ProblemDetail> handleEntityNotFoundException(
        EntityNotFoundException ex, 
        HttpServletRequest request) {
    ProblemDetail problemDetail = forStatusAndDetail(NOT_FOUND, ex.getMessage());
    problemDetail.setTitle("entity.not.found");
    return ResponseEntity.ok(problemDetail);
}

支持的其他状态：

accepted()
badRequest()
noContent()
notFound()
unprocessableEntity()

自定义body和header的示例：

@GetMapping("/customHeader")
ResponseEntity<String> customHeader() {
    return ResponseEntity.ok()
        .header("Custom-Header", "foo")
        .body("Custom header set");
}

或者使用传统构造函数和自定义状态：

return new ResponseEntity<>(body, HttpStatus.OK);

参考：

• https://www.baeldung.com/spring-response-entity
• https://www.baeldung.com/spring-request-response-body
• https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/http/ResponseEntity.html