Spring MVC, JSON，字符串字段序列化错误，长度超过1000个字符

Question

我尝试通过注释@ResponseBody将实体列表作为JSON数据从服务器发送到客户端。问题是长度超过1000的文本字段序列化不正确。在这种情况下，字符串替换为空符号"u0000"序列。

我配置JSON映射器:

@Configuration
@EnableWebMvc
@EnableScheduling
@ComponentScan({"configs", "controllers", "services", "models"})
public class WebConfig
{
    @Bean RequestMappingHandlerAdapter requestMappingHandlerAdapter()
    {
        RequestMappingHandlerAdapter reqMapHAdapter=new RequestMappingHandlerAdapter();
        Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
        builder.indentOutput(true);
        MappingJackson2HttpMessageConverter httpMsgConv=new MappingJackson2HttpMessageConverter(builder.build());
        httpMsgConv.setPrettyPrint(true);
        ArrayList<MediaType> mediaTypes=new ArrayList<>();
        mediaTypes.add(new MediaType("application", "json", StandardCharsets.UTF_8));
        httpMsgConv.setSupportedMediaTypes(mediaTypes);
        ArrayList<HttpMessageConverter<?>> msgConvs=new ArrayList<>();
        msgConvs.add(httpMsgConv);
        reqMapHAdapter.setMessageConverters(msgConvs);
        return reqMapHAdapter;
    }
    ...
}

控制器的方法:

@Controller
public class MyController
{
    @RequestMapping(value={GET_MESSAGES_URL}, method=RequestMethod.GET)
    @ResponseBody List<MessageViewItem> getMessages()
    {
        // getting List<MesssageViewItem>
        List<MessageViewItem> messages=...;
        return messages;
    }
}

MessageViewItem类:

public class MessageViewItem 
{
    private String  text,
                    localizedSendingDate;
    private UserShortViewItem author;
    private Long  messageId;
    // default constructor, getters and setters ...
}

和结果，如果text.length()<=1000:

[ {
  "text" : "123",
  "localizedSendingDate" : "1 day ago",
  "author" : {
    "viewName" : "John Doe",
    "imageUrl" : "/test_web_spring/images/usersImages/0/0/4.jpg",
    "id" : 940
  },
  "messageId" : 3540
} ]

如果text.length()>1000(我从消息中剪切了一大段"u0000"):

[ {
  "text" : " : u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000
u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000",
  "localizedSendingDate" : "3 hour ago",
  "author" : {
    "viewName" : "John Doe",
    "imageUrl" : "/test_web_spring/images/usersImages/0/0/4.jpg",
    "id" : 940
  },
  "messageId" : 3812
} ]

尽管如此，手动调用ObjectMapper。writeValueAsString按预期工作，通常序列化长度超过1000个字符的文本字段。

有什么想法，如何解决这个问题?

ADD: Test controller的method:

@RequestMapping(value={"/testJsonConv"}, method=RequestMethod.GET)
@ResponseBody MessageViewItem testJsonConv()
{
    MessageViewItem msgViewItem=new MessageViewItem();
    msgViewItem.setText("Sed ut perspiciatis, unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam eaque ipsa, quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt, explicabo. nemo enim ipsam voluptatem, quia voluptas sit, aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos, qui ratione voluptatem sequi nesciunt, neque porro quisquam est, qui dolorem ipsum, quia dolor sit, amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt, ut labore et dolore magnam aliquam quaerat voluptatem. ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? quis autem vel eum iure reprehenderit, qui in ea voluptate velit esse, quam nihil molestiae consequatur, vel illum, qui dolorem eum fugiat, quo voluptas nulla pariatur?Sed ut perspiciatis, unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam eaque ipsa, quae ab illo");      
    return msgViewItem;
}

result(cut large part "u0000"):

{
  "text" : " : u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000u0000",
  "localizedSendingDate" : null,
  "author" : null,
  "messageId" : null
}

Answer 1

我看到两个可能的解决方案:

1. 使用显式转换为JSON，像这样:

   @ controllerMyController的公共类{

   // manually convert you'r data to JSON string, and send as text
   @RequestMapping(value={GET_MESSAGES_URL}, 
       method=RequestMethod.GET, produces=MediaType.TEXT_PLAIN) throws ...
   @ResponseBody String getMessages()
   {
       // getting List<MesssageViewItem>
       List<MessageViewItem> messages=...;
       return mapper.writeValueAsString(messages);
   }
   

   }

不要忘记为文本媒体类型添加消息转换器:

@Configuration
@EnableScheduling
@EnableAsync
@ComponentScan({"configs", "models"})
public class WebConfig 
{
    @Bean RequestMappingHandlerAdapter requestMappingHandlerAdapter()
    {
        RequestMappingHandlerAdapter reqMapHAdapter=new RequestMappingHandlerAdapter();
        ArrayList<HttpMessageConverter<?>> msgConvs=new ArrayList<>();
        StringHttpMessageConverter stringConverter = new StringHttpMessageConverter(Charset.forName("UTF-8"));
        stringConverter.setSupportedMediaTypes(Arrays.asList(MediaType.TEXT_PLAIN));
        msgConvs.add(stringConverter);
        reqMapHAdapter.setMessageConverters(msgConvs);
        return reqMapHAdapter;
    }
    ...
}

更新依赖关系后，我的项目问题是失望的。我将spring更新到4.2.4，并且(可能是最重要的)- jackson，从codehaus更新到最后一个更快的xml版本。

这是一个帖子，我想标记作为答案。作者建议更新杰克逊图书馆，这对我有帮助。但是,不幸的是，我找不到这篇文章。