What annotations are used to return json?

The returned json is annotated with "@ResponseBody". "@ResponseBody" is applied to the method. "@ResponseBody" means that the return result of the method is directly written into the "HTTP response body".

#This article will introduce two examples to demonstrate the JSON return annotation method.

Example 1

@ResponseBody acts on the method. @ResponseBody means that the return result of the method is directly written into the HTTP response body, and the data is generally obtained asynchronously. When using [that is, AJAX], after using @RequestMapping, the return value is usually parsed as a jump path, but after adding @ResponseBody, the return result will not be parsed as a jump path, but will be written directly into the HTTP response body. For example, if you obtain json data asynchronously and add @ResponseBody, the json data will be returned directly. @RequestBody Inserts the HTTP request body into the method, using an appropriate HttpMessageConverter to write the request body to an object.

The following parts are located in Spring-mvc.xml or dispatcherServlet-servlet.xml (ServletName-servlet.xml replaced Spring-mvc.xml in Spring 3.0)

<!-- 用于将对象转换为 JSON  -->  
    <bean>  
        <property>  
            <list>  
                <value>text/plain;charset=UTF-8</value>  
            </list>
        </property>
    </bean>  
    <bean></bean>  
    <bean>  
        <property>  
            <list>  
                <ref></ref>
                <ref></ref>  
            </list>  
        </property>  
    </bean>

In the corresponding Controller Medium:

@RequestMapping(value="/login",method=RequestMethod.POST)
    public @ResponseBody User login(String username,String password){
        User user = userService.login(username, password);
        return user;
    }

Here I use the jackson package:

(1) jackson-core 2.5.0

(2) jackson-databind 2.5.0

(3)jackson-annotations 2.5.0

Build path after import;

Warning: If you use the pojo class generated by orm tools such as hibernate, one-to-one, one-to-many, etc. relationships may be An infinite loop of json will be output:

You need to import com.fasterxml.jackson.annotation.JsonIgnore in the pojo class, and add the @JsonIgnore annotation to the class that needs to be shielded, so that the annotated attributes will not appear. in json.

Example 2

@ResponseBody  
    @RequestMapping(value = "/login")  
    public ModelAndView ajaxLogin(Model model,User user,HttpServletRequest request, HttpSession session){  
        String errorMessage=loginCommon(model, user, request, session);  
        Map map=new HashMap();  
        if(ValueWidget.isNullOrEmpty(errorMessage)){  
            map.put(Constant2.AJAX_LOGIN_RESULT, "success");  
        }else{  
            map.put(Constant2.AJAX_LOGIN_RESULT, "failed");  
        }  
        map.put("error", errorMessage);  
        model.addAttribute("user", null);  
        return new ModelAndView(new MappingJacksonJsonView(),map);  
    }

or

model.addAttribute("user", user1);

operation result:

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