Java @ResponseBody , ResponseEntity Spring 将对象作为 JSON 返回
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@ResponseBody , ResponseEntity Spring return Object as JSON
提问by Mohammad Karmi
I'm using Spring version 4 ( spring data), I want to return Object as JSON , I wonderd that the following code worked even without annotating the user class wtih xmlRootElement:
我正在使用 Spring 版本 4（spring 数据），我想将 Object 作为 JSON 返回，我想知道即使没有使用 xmlRootElement 注释用户类，以下代码也能工作：
@RequestMapping(value = "/resources/users", method = RequestMethod.GET)
public ResponseEntity<User> getUserByLogonId(OAuth2Authentication auth) {
String userLogonId = ((org.springframework.security.core.userdetails.User) auth.getUserAuthentication()
.getPrincipal()).getUsername();
UsersServices usersServices = new UsersServicesImpl(usersOperations);
User user = usersServices.findByLogonId(userLogonId);
HttpStatus userStatus = HttpStatus.NOT_FOUND;
if (user != null) {
userStatus = HttpStatus.FOUND;
}
return new ResponseEntity<User>(user, userStatus);
}
can any body explain ? is ResponseBody/ResponseEntity do the work itself ? when I need to annotate the object class to be returned as JSON.
任何机构都可以解释吗？ResponseBody/ResponseEntity 是自己做的工作吗？当我需要注释要作为 JSON 返回的对象类时。
采纳答案by sunkuet02
@RestControlleritself adds @ResponseBodyannotation. You can see it in the Github Issue
@RestController本身添加了@ResponseBody注释。你可以在Github Issue 中看到
You can also check the official spring tutorials. Here you can check the below lines and examples:
您还可以查看官方 spring 教程。您可以在此处查看以下行和示例：
These controller methods return simple POJOs -
Collection<Bookmark>, andBookmark, etc., in all but theaddcase. When an HTTP request comes in that specifies anAccept header,Spring MVCloops through the configuredHttpMessageConverteruntil it finds one that can convert from thePOJOdomain model types into the content-type specified in theAccept header, if so configured.
这些控制器方法返回简单的 POJO -
Collection<Bookmark>、 和Bookmark等，除了这种add情况。当传入指定 的 HTTP 请求时Accept header，Spring MVC循环遍历已配置，HttpMessageConverter直到找到可以从POJO域模型类型转换为 中指定的内容类型Accept header（如果已配置）的请求。
You can also follow the below lines and examples from Official doc
您还可以按照官方文档中的以下行和示例进行操作
@RestController is a stereotype annotation that combines @ResponseBody and @Controller. More than that, it gives more meaning to your Controller and also may carry additional semantics in future releases of the framework.
@RestController 是结合@ResponseBody 和@Controller 的构造型注解。更重要的是，它为您的控制器赋予了更多意义，并且还可能在框架的未来版本中携带额外的语义。
And,
和，
As with @RequestBody and @ResponseBody, Spring uses HttpMessageConverter to convert from and to the request and response streams.
与@RequestBody 和@ResponseBody 一样，Spring 使用 HttpMessageConverter 来转换请求和响应流。
回答by Nikolai
xmlRootElementis using for representing of a object as XML element in an XML document. XML has nothing to do with JSON.
When you annotate your class by @RestControllerit combines @Controllerfor class and @ResponseBodyfor every method. And then HttpMessageConverterconverts from and to the request and response streams.@ResponseEntityis using for forming http response with custom params (headers, http code and etc.). For example:
xmlRootElement用于将对象表示为 XML 文档中的 XML 元素。XML 与 JSON 无关。
当您通过@RestController它@Controller为类和@ResponseBody每个方法注释您的类时。然后HttpMessageConverter在请求和响应流之间进行转换。@ResponseEntity用于使用自定义参数（标头、http 代码等）形成 http 响应。例如：
return new ResponseEntity<String>("Hello World", responseHeaders, HttpStatus.CREATED);
回答by Srinivas Seema
Spring boot uses the Hymanson json libraries for marshalling and unmarshalling the java objects to/from json objects no need any explicit configuration.
Spring Boot 使用 Hymanson json 库将 java 对象编组和解组到 json 对象，无需任何显式配置。
