SpringMVC中使用@ResponseBody注解将任意POJO对象返回值转换成json进行返回

@ResponseBody

作用： 

      该注解用于将Controller的方法返回的对象，通过适当的HttpMessageConverter转换为指定格式后，写入到Response对象的body数据区。

使用时机：

      返回的数据不是html标签的页面，而是其他某种格式的数据时（如json、xml等）使用；

导包：

除了一些spring的包之外，还需要jackson-annotations.jar , jackson-core.jar , jackson-databind.jar 这三个包

开启@ResponseBody注解---在MVC中配置转换器：

1 <bean  
2        class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">  
3        <property name="messageConverters">  
4            <list>  
5             <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"></bean>  
6               <!--   <ref bean="mappingJacksonHttpMessageConverter" />-->  
7            </list>  
8        </property>  
9    </bean>  

配置完就可以直接使用了：

 1     @RequestMapping(value="/getStudentMistakesList", method = RequestMethod.GET)
 2     @ResponseBody
 3     public EduReturnJson getStudentMistakesList(HttpServletRequest request, HttpServletResponse response) throws Exception {
 4         Map<String,String> map = getParamMap(request);
 5         List<Map<String, String>> mistakesList = eduStudentMistakesService.getStudentMistakesList(map);
 6         if(mistakesList != null){
 7             eduReturnJson = new EduReturnJson(1, "", mistakesList);
 8             return eduReturnJson;
 9         }else{
10             return new EduReturnJson(0, "", mistakesList);
11         }
12     }

这时返回数据已经转换为json格式：

1 {"ret":1,"msg":"","data":[{"num":"34","courseid":"12","coursename":"语文"},{"num":"0","courseid":"13","coursename":"数学"},{"num":"0","courseid":"14","coursename":"英语"}],"count":0}

导包：

除了一些spring的包之外，还需要jackson-annotations.jar , jackson-core.jar , jackson-databind.jar 这三个包

开启@ResponseBody注解---在MVC中配置转换器：

1 <bean  
2        class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">  
3        <property name="messageConverters">  
4            <list>  
5             <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"></bean>  
6               <!--   <ref bean="mappingJacksonHttpMessageConverter" />-->  
7            </list>  
8        </property>  
9    </bean>  

配置完就可以直接使用了：

 1     @RequestMapping(value="/getStudentMistakesList", method = RequestMethod.GET)
 2     @ResponseBody
 3     public EduReturnJson getStudentMistakesList(HttpServletRequest request, HttpServletResponse response) throws Exception {
 4         Map<String,String> map = getParamMap(request);
 5         List<Map<String, String>> mistakesList = eduStudentMistakesService.getStudentMistakesList(map);
 6         if(mistakesList != null){
 7             eduReturnJson = new EduReturnJson(1, "", mistakesList);
 8             return eduReturnJson;
 9         }else{
10             return new EduReturnJson(0, "", mistakesList);
11         }
12     }

这时返回数据已经转换为json格式：

1 {"ret":1,"msg":"","data":[{"num":"34","courseid":"12","coursename":"语文"},{"num":"0","courseid":"13","coursename":"数学"},{"num":"0","courseid":"14","coursename":"英语"}],"count":0}