Spring mvc SpringMVC：在每个响应中追加新行

考虑简单的@RestController，返回一个映射：

@GetMapping("/foo")
public ResponseEntity<Map<String, Object>> foo() {
    Map<String, Any> map = HashMap<>();
    map.put(...);
    return ResponseEntity(map, HttpStatus.OK);
}

并加入:

override fun addFormatters(registry: FormatterRegistry) {
    registry.addFormatter(MapFormatter())
}

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不幸的是，它从来没有被调用过，我想格式化程序是用来做其他事情的。

您可以使用Jackson将其序列化为字符串，然后附加所需内容，并将其作为响应实体的主体

大概是这样的：

//Somewhere in the class fields
private final ObjectMapper mapper = new ObjectMapper();

@GetMapping("/foo")
public ResponseEntity<Map<String, Object>> foo() {
    Map<String, Any> map = HashMap<>();
    map.put(...);
    return ResponseEntity(mapper.writeValueAsString(map) + "/n", HttpStatus.OK);
}

---

最后通过

HttpMessageConverter

完成：

class GsonHttpMessageConverter : AbstractHttpMessageConverter<Map<String, Any?>>(
        MediaType("application", "json", Charset.forName("UTF-8"))) {

    override fun readInternal(clazz: Class<out Map<String, Any?>>, inputMessage: HttpInputMessage)
            = Gson().fromJson(IOUtils.toString(inputMessage.body, "UTF-8"), clazz)

    override fun supports(clazz: Class<*>) = Map::class.java.isAssignableFrom(clazz)

    override fun writeInternal(payload: Map<String, Any?>, outputMessage: HttpOutputMessage) {   
        outputMessage.body.write(Gson().toJson(payload) + "\n".toByteArray())
    }
}

类GsonHttpMessageConverter:AbstractHttpMessageConverter( MediaType（“应用程序”、“json”、Charset.forName（“UTF-8”））{ 重写fun readInternal（clazz:Class，inputMessage:HttpInputMessage） =Gson（）.fromJson（IOUtils.toString（inputMessage.body，“UTF-8”），clazz） 覆盖有趣的支持（clazz:Class）=Map:：Class.java.isAssignableFrom（clazz） 重写fun writeInternal（有效负载：Map，outputMessage:HttpOutputMessage）{ outputMessage.body.write（Gson（）.toJson（有效负载）+“\n”.toByteArray（）） } }

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我正在寻找某种通用解决方案，即

@配置

或

过滤器

，可以处理此问题。您的最后一部分是我正在寻找的，但仍然不确定如何实现这一点。

//Need to look at the documentation and figure out how to set this.    
@Bean
public Jackson2ObjectMapperBuilderCustomizer mapperBuilderCustomizer() {
    return jacksonObjectMapperBuilder -> jacksonObjectMapperBuilder
}

class GsonHttpMessageConverter : AbstractHttpMessageConverter<Map<String, Any?>>(
        MediaType("application", "json", Charset.forName("UTF-8"))) {

    override fun readInternal(clazz: Class<out Map<String, Any?>>, inputMessage: HttpInputMessage)
            = Gson().fromJson(IOUtils.toString(inputMessage.body, "UTF-8"), clazz)

    override fun supports(clazz: Class<*>) = Map::class.java.isAssignableFrom(clazz)

    override fun writeInternal(payload: Map<String, Any?>, outputMessage: HttpOutputMessage) {   
        outputMessage.body.write(Gson().toJson(payload) + "\n".toByteArray())
    }
}