具有未知动态属性的 Jackson 反序列化 [英] Jackson deserialization with unknown dynamic properties

问题描述

我有一个 JSON 字符串，例如:

I have a JSON string like:

"shipping_profiles": {
  "563": {
    "name": "name",
    "value": "value"            
  },
  "564": {
    "name": "name",
    "value": "value"            
  },
  "565": {
    "name": "name",
    "value": "value"            
  },
  "566": {
    "name": "name",
    "value": "value"            
  }
}

现在我用 Jackson 2.0 解析它.我正在尝试从 JSON 字符串中获取 List.

Now I am parsing it with Jackson 2.0. I am trying to get a List<shipping_profiles> from the JSON string.

有可能吗?

推荐答案

您的 shipping_profiles 属性看起来不像数组.它代表具有动态属性的对象，所以我们应该把它当作一个对象来对待.如果我们对属性一无所知，我们可以使用 @JsonAnySetter 注释.算法可能如下所示:

Your shipping_profiles property doesn't look like array. It represent object with dynamic properties, so we should treat it like an object. If we do not know anything about properties we can use @JsonAnySetter annotation. Algorithm could looks like below:

1. 将 JSON 反序列化为 JSON 模型类.
2. 使用 ObjectMapper 将动态对象(地图)转换为应用的 POJO 类
3. 随时使用应用的 POJO.

请参阅我的示例实现.我希望，它可以帮助您解决您的问题.输入 JSON:

Please see my example implementation. I hope, it help you solve your problem. Input JSON:

{
   "shipping_profiles":{
      "563":{
         "name":"name563",
         "value":"value563"
      },
      "564":{
         "name":"name564",
         "value":"value564"
      },
      "565":{
         "name":"name565",
         "value":"value565"
      },
      "566":{
         "name":"name566",
         "value":"value566"
      }
   }
}

示例程序:

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import com.fasterxml.jackson.annotation.JsonAnySetter;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JacksonProgram {

    public static void main(String[] args) throws IOException {
        ObjectMapper mapper = new ObjectMapper();

        File source = new File("X:/test.json");
        Entity entity = mapper.readValue(source, Entity.class);
        ShippingProfiles shippingProfiles = entity.getShippingProfiles();
        List<Map<String, String>> profileMaps = shippingProfiles.getProfiles();

        List<Profile> profiles = new ArrayList<Profile>(profileMaps.size());
        for (Map<String, String> item : profileMaps) {
            profiles.add(mapper.convertValue(item, Profile.class));
        }
        System.out.println(profiles);
    }
}

class Entity {

    @JsonProperty("shipping_profiles")
    private ShippingProfiles shippingProfiles;

    public ShippingProfiles getShippingProfiles() {
        return shippingProfiles;
    }

    public void setShippingProfiles(ShippingProfiles shippingProfiles) {
        this.shippingProfiles = shippingProfiles;
    }
}

class ShippingProfiles {

    private List<Map<String, String>> profiles = new ArrayList<Map<String, String>>();

    @JsonAnySetter
    public void setDynamicProperty(String name, Map<String, String> map) {
        profiles.add(map);
    }

    public List<Map<String, String>> getProfiles() {
        return profiles;
    }

    public void setProfiles(List<Map<String, String>> profiles) {
        this.profiles = profiles;
    }
}

class Profile {

    private String name;
    private String value;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }

    @Override
    public String toString() {
        return "Profile [name=" + name + ", value=" + value + "]";
    }
}

以上应用打印:

[Profile [name=name563, value=value563], Profile [name=name564, value=value564], Profile [name=name565, value=value565], Profile [name=name566, value=value566]]

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