最简单的方法是抛出一个ResponseStatusException:

@RequestMapping(value = "/matches/{matchId}", produces = "application/json")
@ResponseBody
public String match(@PathVariable String matchId, @RequestBody String body) {
    String json = matchService.getMatchJson(matchId);
    if (json == null) {
        throw new ResponseStatusException(HttpStatus.NOT_FOUND);
    }
    return json;
}

这不是最紧凑的方式，但在我看来很干净:

if(json == null) {
    throw new BadThingException();
}
...

@ExceptionHandler(BadThingException.class)
@ResponseStatus(value = HttpStatus.BAD_REQUEST)
public @ResponseBody MyError handleException(BadThingException e) {
    return new MyError("That doesn’t work");
}

如果使用Spring 3.1+，您可以在异常处理方法中使用@ResponseBody，否则使用ModelAndView或其他东西。

@ResponseBody不能与@ExceptionHandler [sp -6902] #11567一起工作

在控制器中处理异常而无需显式返回ResponseEntity的最简单、最干净的方法是添加@ExceptionHandler方法。

使用Spring Boot 2.0.3.RELEASE的示例片段:

// Prefer static import of HttpStatus constants as it's cleaner IMHO

// Handle with no content returned
@ExceptionHandler(IllegalArgumentException.class)
@ResponseStatus(BAD_REQUEST)
void onIllegalArgumentException() {}

// Return 404 when JdbcTemplate does not return a single row
@ExceptionHandler(IncorrectResultSizeDataAccessException.class)
@ResponseStatus(NOT_FOUND)
void onIncorrectResultSizeDataAccessException() {}

// Catch all handler with the exception as content
@ExceptionHandler(Exception.class)
@ResponseStatus(I_AM_A_TEAPOT)
@ResponseBody Exception onException(Exception e) {
  return e;
}

题外话:

如果在所有上下文/用法中，matchService.getMatchJson(matchId) == null是无效的，那么我的建议是让getMatchJson抛出一个异常，例如，IllegalArgumentException，而不是返回null，并让它冒泡泡到控制器的@ExceptionHandler。 如果用null来测试其他条件，那么我将有一个特定的方法，例如matchService.hasMatchJson(matchId)。一般来说，我尽可能避免null，以避免意外的NullPointerException。

这里有一个不同的方法。创建一个带有@ResponseStatus注解的自定义Exception，如下所示。

@ResponseStatus(code = HttpStatus.NOT_FOUND, reason = "Not Found")
public class NotFoundException extends Exception {

    public NotFoundException() {
    }
}

需要的时候扔出去。

@RequestMapping(value = "/matches/{matchId}", produces = "application/json")
@ResponseBody
public String match(@PathVariable String matchId) {
    String json = matchService.getMatchJson(matchId);
    if (json == null) {
        throw new NotFoundException();
    }
    return json;
}

正如在一些回答中提到的，可以为您想要返回的每个HTTP状态创建一个异常类。我不喜欢为每个项目的每个状态创建一个类的想法。这是我想出的替代方案。

创建接受HTTP状态的通用异常 创建一个Controller Advice异常处理程序

让我们来看看代码

package com.javaninja.cam.exception;

import org.springframework.http.HttpStatus;


/**
 * The exception used to return a status and a message to the calling system.
 * @author norrisshelton
 */
@SuppressWarnings("ClassWithoutNoArgConstructor")
public class ResourceException extends RuntimeException {

    private HttpStatus httpStatus = HttpStatus.INTERNAL_SERVER_ERROR;

    /**
     * Gets the HTTP status code to be returned to the calling system.
     * @return http status code.  Defaults to HttpStatus.INTERNAL_SERVER_ERROR (500).
     * @see HttpStatus
     */
    public HttpStatus getHttpStatus() {
        return httpStatus;
    }

    /**
     * Constructs a new runtime exception with the specified HttpStatus code and detail message.
     * The cause is not initialized, and may subsequently be initialized by a call to {@link #initCause}.
     * @param httpStatus the http status.  The detail message is saved for later retrieval by the {@link
     *                   #getHttpStatus()} method.
     * @param message    the detail message. The detail message is saved for later retrieval by the {@link
     *                   #getMessage()} method.
     * @see HttpStatus
     */
    public ResourceException(HttpStatus httpStatus, String message) {
        super(message);
        this.httpStatus = httpStatus;
    }
}

然后我创建一个控制器通知类

package com.javaninja.cam.spring;


import com.javaninja.cam.exception.ResourceException;

import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ExceptionHandler;


/**
 * Exception handler advice class for all SpringMVC controllers.
 * @author norrisshelton
 * @see org.springframework.web.bind.annotation.ControllerAdvice
 */
@org.springframework.web.bind.annotation.ControllerAdvice
public class ControllerAdvice {

    /**
     * Handles ResourceExceptions for the SpringMVC controllers.
     * @param e SpringMVC controller exception.
     * @return http response entity
     * @see ExceptionHandler
     */
    @ExceptionHandler(ResourceException.class)
    public ResponseEntity handleException(ResourceException e) {
        return ResponseEntity.status(e.getHttpStatus()).body(e.getMessage());
    }
}

使用它

throw new ResourceException(HttpStatus.BAD_REQUEST, "My message");

http://javaninja.net/2016/06/throwing-exceptions-messages-spring-mvc-controller/

我将稍微改变一下实现:

首先，我创建了一个UnknownMatchException:

@ResponseStatus(HttpStatus.NOT_FOUND)
public class UnknownMatchException extends RuntimeException {
    public UnknownMatchException(String matchId) {
        super("Unknown match: " + matchId);
    }
}

注意@ResponseStatus的使用，它将被Spring的ResponseStatusExceptionResolver识别。如果抛出异常，它将创建具有相应响应状态的响应。(我还擅自将状态代码更改为404 - Not Found，我认为这更适合这个用例，但您可以坚持使用HttpStatus。BAD_REQUEST如果你喜欢。)

接下来，我将更改MatchService具有以下签名:

interface MatchService {
    public Match findMatch(String matchId);
}

最后，我将更新控制器并委托给Spring的MappingJackson2HttpMessageConverter来自动处理JSON序列化(如果您将Jackson添加到类路径中，并将@EnableWebMvc或<mvc:annotation-driven />添加到配置中，则默认添加JSON序列化。请参阅参考文档):

@RequestMapping(value = "/matches/{matchId}", produces = MediaType.APPLICATION_JSON_VALUE)
@ResponseBody
public Match match(@PathVariable String matchId) {
    // Throws an UnknownMatchException if the matchId is not known
    return matchService.findMatch(matchId);
}

注意，将域对象与视图对象或DTO对象分离是非常常见的。这可以通过添加一个小型DTO工厂来轻松实现，该工厂返回可序列化的JSON对象:

@RequestMapping(value = "/matches/{matchId}", produces = MediaType.APPLICATION_JSON_VALUE)
@ResponseBody
public MatchDTO match(@PathVariable String matchId) {
    Match match = matchService.findMatch(matchId);
    return MatchDtoFactory.createDTO(match);
}