ResponseEntity <T>和@ResponseBody有什么区别？

Question

我的控制器中有一个简单的处理程序,它返回一条消息

@RequestMapping(value = "/message")
@ResponseBody
public Message get() {
    return new Message(penguinCounter.incrementAndGet() + " penguin!");
}

同时我可以使用这样的东西

@RequestMapping(value = "/message")
ResponseEntity<Message> get() {
    Message message = new Message(penguinCounter.incrementAndGet() + " penguin!");
    return new ResponseEntity<Message>(message, HttpStatus.OK);
}

这两种方法有什么区别？我们不考虑HttpStatus :)

Answer 1

ResponseEntity将为您定义任意HTTP响应头提供一些额外的灵活性.在这里查看第4个构造函数:

http://docs.spring.io/spring/docs/3.0.x/api/org/springframework/http/ResponseEntity.html

ResponseEntity(T body, MultiValueMap<String,String> headers, HttpStatus statusCode) 

此处提供了可能的HTTP响应标头列表:

http://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Responses

一些常用的是Status,Content-Type和Cache-Control.

如果您不需要,使用@ResponseBody将更简洁一些.

Answer 2

HttpEntity表示由headers和body组成的 HTTP请求或响应。

// Only talks about body & headers, but doesn't talk about status code
public HttpEntity(T body, MultiValueMap<String,String> headers)

ResponseEntity扩展了 HttpEntity 但也添加了 Http 状态代码。

// i.e ResponseEntity = HttpEntity + StatusCode
public ResponseEntity(T body, MultiValueMap<String,String> headers, HttpStatus statusCode)

因此用于完全 配置HTTP 响应。

例如：

@ControllerAdvice 
public class JavaWebExeptionHandler {

    @Autowired
    ExceptionErrorCodeMap exceptionErrorCodeMap;

    @ExceptionHandler(RuntimeException.class)
    public final ResponseEntity<ExceptionResponseBody> handleAllExceptions(Exception ex) {
        Integer expCode = exceptionErrorCodeMap.getExpCode(ex.getClass());
        // We have not added headers to response here, If you want you can add by using respective constructor
        return new ResponseEntity<ExceptionResponseBody>(new ExceptionResponseBody(expCode, ex.getMessage()),
                HttpStatus.valueOf(expCode));
    }

}

@ResponseBody表示使用它的方法的返回值绑定到响应体 （意味着方法的返回值被视为Http响应体）