如何使用Jackson将嵌套的ObjectId序列化为String？ [英] How to serialize nested ObjectId to String with Jackson?

问题描述

很多 问题有关从 ObjectId 转换为 String 与杰克逊。所有答案建议创建自己的 JsonSerializer< ObjectId> 或使用 @JsonSerialize注释 ObjectId 字段（using = ToStringSerializer.class）。

There are many questions concerning conversion from ObjectId to String with jackson. All answers suggest either creating own JsonSerializer<ObjectId> or annotating the ObjectId field with @JsonSerialize(using = ToStringSerializer.class).

但是，我有一张有时包含<$ c $的地图c> ObjectIds ，即：

However, I have a map that sometimes contains ObjectIds, i.e.:

class Whatever {
  private Map<String, Object> parameters = new HashMap<>();
  Whatever() {
    parameters.put("tom", "Cat");
    parameters.put("jerry", new ObjectId());
  }
}

我希望杰克逊将其转换为：

I want jackson to convert it to:

{
  "parameters": {
    "tom": "cat",
    "jerry": "57076a6ed1c5d61930a238c5"
  }
}

但我得到：

{
  "parameters": {
    "tom": "cat",
    "jerry": {
      "date": 1460103790000,
      "machineIdentifier": 13747670,
      "processIdentifier": 6448,
      "counter": 10631365,
      "time": 1460103790000,
      "timestamp": 1460103790,
      "timeSecond": 1460103790
    }
  }
}

我已经注册了转换（在Spring中）

I have registered the conversion (in Spring) with

public class WebappConfig extends WebMvcConfigurerAdapter {
  @Override
  public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder
        .serializerByType(ObjectId.class, new ToStringSerializer());
    MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter(builder.build());
    converters.add(converter);
  }
}

第一级 ObjectIds 已正确转换。如何让杰克逊转换成嵌套的？我是否必须为此地图编写自定义转换器？

And the first-level ObjectIds are converted correctly. How to make jackson convert also the nested ones? Do I have to write custom converter for this map?

请记住，此地图可以多次嵌套（即包含另一张地图）。我只想将 ObjectId 转换为 String 每当jackson看到它时。

Keep in mind that this Map can be nested multiple times (i.e. contain another maps). I just want to convert ObjectId to String whenever jackson sees it.

推荐答案

我想你从 org那里拿走了 org.bson.types.ObjectId 。 springframework.boot：弹簧引导起动数据的mongodb 。你的代码对我来说非常好。我可以看到的一件事是你没有在 WebappConfig 上面显示 @Configuration 注释。

I suppose that you are taking about org.bson.types.ObjectId from org.springframework.boot:spring-boot-starter-data-mongodb. Your code works perfectly fine for me. 1 thing i can see is that you don't show @Configuration annotation above WebappConfig.

这是我的演示项目，你可以在你的设置上进行测试吗？

Here is my demo project, can you test it on yours setup?

Application.java

import com.fasterxml.jackson.databind.ser.std.ToStringSerializer;
import org.bson.types.ObjectId;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @Configuration
    public static class WebappConfig extends WebMvcConfigurerAdapter {
        @Override
        public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
            Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
            builder
                    .serializerByType(ObjectId.class, new ToStringSerializer());
            MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter(builder.build());
            converters.add(converter);
        }
    }

    @RestController
    public static class MyRestController {

        @ResponseBody
        @RequestMapping("/")
        public Whatever method() {
            return new Whatever();
        }
    }

    public static class Whatever {
        private Map<String, Object> parameters = new HashMap<>();

        public Whatever() {
            parameters.put("tom", "Cat");
            parameters.put("jerry", new ObjectId());
        }

        public Map<String, Object> getParameters() {
            return parameters;
        }

        public void setParameters(Map<String, Object> parameters) {
            this.parameters = parameters;
        }
    }
}

从127.0回复.0.1：8080

{
  "parameters": {
    "tom": "Cat",
    "jerry": "5709df1cf0d9550b4de619d2"
  }
}

Gradle：

dependencies {
    compile("org.springframework.boot:spring-boot-starter-data-mongodb")
    compile("org.springframework.boot:spring-boot-starter-web")
}

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