SpringMVC返回json数据的三种方式

1、第一种方式是spring2时代的产物，也就是每个json视图controller配置一个Jsoniew。

如：<bean id="defaultJsonView" class="org.springframework.web.servlet.view.json.MappingJacksonJsonView"/> 

或者<bean id="defaultJsonView" class="org.springframework.web.servlet.view.json.MappingJackson2JsonView"/>

同样要用jackson的jar包。

2、第二种使用JSON工具将对象序列化成json，常用工具Jackson，fastjson，gson。

利用HttpServletResponse，然后获取response.getOutputStream()或response.getWriter()

直接输出。

示例：

 public class JsonUtil
 {

     private static Gson gson=new Gson();


     /**
      * @MethodName : toJson
      * @Description : 将对象转为JSON串，此方法能够满足大部分需求
      * @param src
      *            :将要被转化的对象
      * @return :转化后的JSON串
      */
     public static String toJson(Object src) {
         if (src == null) {
             return gson.toJson(JsonNull.INSTANCE);
         }
         return gson.toJson(src);
     }
 }

3、第三种利用spring mvc3的注解@ResponseBody

例如：

 @ResponseBody
   @RequestMapping("/list")
   public List<String> list(ModelMap modelMap) {
     String hql = "select c from Clothing c ";
     Page<Clothing> page = new Page<Clothing>();
     page.setPageSize(6);
     page  = clothingServiceImpl.queryForPageByHql(page, hql);

     return page.getResult();
   }

然后使用spring mvc的默认配置就可以返回json了，不过需要jackson的jar包哦。

注意：当springMVC-servlet.xml中使用<mvc:annotation-driven />时，如果是3.1之前已经默认注入AnnotationMethodHandlerAdapter，3.1之后默认注入RequestMappingHandlerAdapter只需加上上面提及的jar包即可!

如果是手动注入RequestMappingHandlerAdapter 可以这样设置

配置如下：

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left: 760px; top: 1726px; width: 29px; height: 14px; z-index: 99;"></div></div></div><ol start="1" class="dp-xml" style="padding: 0px; border: none; list-style-position: initial; list-style-image: initial; color: rgb(92, 92, 92); margin: 0px 0px 1px 45px !important;"><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(108, 226, 108); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;"><span class="tag" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;"><</span><span class="tag-name" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;">bean</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;"> </span><span class="attribute" style="margin: 0px; padding: 0px; border: none; color: red; background-color: inherit;">class</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">=</span><span class="attribute-value" style="margin: 0px; padding: 0px; border: none; color: blue; background-color: inherit;">"org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter"</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">  </span></span></li><li style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(108, 226, 108); list-style: decimal-leading-zero outside; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">        <span class="attribute" style="margin: 0px; padding: 0px; border: none; color: red; background-color: inherit;">p:ignoreDefaultModelOnRedirect</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">=</span><span class="attribute-value" style="margin: 0px; padding: 0px; border: none; color: blue; background-color: inherit;">"true"</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;"> </span><span class="tag" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;">></span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">  </span></span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(108, 226, 108); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">            <span class="tag" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;"><</span><span class="tag-name" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;">property</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;"> </span><span class="attribute" style="margin: 0px; padding: 0px; border: none; color: red; background-color: inherit;">name</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">=</span><span class="attribute-value" style="margin: 0px; padding: 0px; border: none; color: blue; background-color: inherit;">"messageConverters"</span><span class="tag" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;">></span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">  </span></span></li><li style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(108, 226, 108); list-style: decimal-leading-zero outside; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">                <span class="tag" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;"><</span><span class="tag-name" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;">list</span><span class="tag" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;">></span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">  </span></span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(108, 226, 108); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">                    <span class="tag" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;"><</span><span class="tag-name" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;">bean</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;"> </span><span class="attribute" style="margin: 0px; padding: 0px; border: none; color: red; background-color: inherit;">class</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">=</span><span class="attribute-value" style="margin: 0px; padding: 0px; border: none; color: blue; background-color: inherit;">"org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"</span><span class="tag" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;">/></span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">  </span></span></li><li style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(108, 226, 108); list-style: decimal-leading-zero outside; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">                <span class="tag" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;"></</span><span class="tag-name" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;">list</span><span class="tag" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;">></span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">  </span></span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(108, 226, 108); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">            <span class="tag" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;"></</span><span class="tag-name" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;">property</span><span class="tag" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;">></span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">  </span></span></li><li style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(108, 226, 108); list-style: decimal-leading-zero outside; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">        <span class="tag" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;"></</span><span class="tag-name" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;">bean</span><span class="tag" style="margin: 0px; padding: 0px; border: none; color: rgb(153, 51, 0); background-color: inherit; font-weight: bold;">></span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">  </span></span></li></ol></div>

添加包
jackson-mapper-asl-*.jar
jackson-core-asl-*.jar

可以看出，使用方式越来越简单，程序员越来越傻，不知道是好事，还是坏事……