Question

我想做定制的嵌套序列化。这是一个示例。我的申请中也有类似情况。我认为我对这里的事情没有很好的了解。似乎有一个SerializationContext传递到serialize方法中。我认为，它可以用于嵌套序列化。我还没有在网上找到一个简单的例子...

但是，我在这里所做的没有用。如果看到输出，它将输出Property对象的所有字段，而我只想获取几个，并且使用不同的名称，等等。

public class Outer {

    private String name;
    private String objectId;

    private List<Property> properties;
    // getters setters 
}

public class Property {
    private Integer id;
    private String info;
    private Date createdOn;
    private String dontCare;


    Property (Integer id) {
        this.createdOn = new Date();
        this.dontCare = ( (id%2 == 0) ? "Y" : "N");
        this.id = id;
        SimpleDateFormat dt = new SimpleDateFormat("mm-dd hh:mm:ss"); 
        this.info = dt.format(createdOn);
    }
   // getters setters
}

public class Practice {

    public static void main (String args[])
    {

        JsonSerializer<List<Property>> listSerializer = new JsonSerializer<List<Property>>() {

            @Override
            public JsonElement serialize(List<Property> src, Type typeOfSource, JsonSerializationContext context) {


                JsonSerializer<Property> serializer = new JsonSerializer<Property>() {  
                    @Override
                    public JsonElement serialize(Property src, Type typeOfSrc, JsonSerializationContext context) {
                        JsonObject property = new JsonObject();
                        property.addProperty("Identifier", src.getId());
                        return property;
                    }
                }; // will implement in a second  

                GsonBuilder gsonBuilder = new GsonBuilder();
                gsonBuilder.registerTypeAdapter(Property.class, serializer);
                Gson customGson = gsonBuilder.setPrettyPrinting().create();  

                JsonObject jsonObject = new JsonObject();
                List<Property> properties = new ArrayList<Property>(src.size());
                String propertiesAsString = "";

                for (Property aProperty : src) {
                    propertiesAsString +=customGson.toJson(aProperty); 
                }

                JsonObject propertiesJsonObject = new JsonObject();
                propertiesJsonObject.addProperty("properties", propertiesAsString);
                return propertiesJsonObject;
            }
        };


        GsonBuilder gsonBuilder4List = new GsonBuilder();
        Type propertyListType = new TypeToken<List<Property>> () {}.getType();
        gsonBuilder4List.registerTypeAdapter(propertyListType, listSerializer);

        Gson customGson4List = gsonBuilder4List.setPrettyPrinting().create();
        String customJSON2 = customGson4List.toJson(giveMePropertyList(3));  

        System.out.println("Property List...");
        System.out.println (customJSON2);
    }

    public static ArrayList<Property> giveMePropertyList (int count)
    {
        ArrayList<Property> list = new ArrayList<Property>();
        for (int i = 0; i < count; i++) {
            int random = (int )(Math.random() * 98768 + 1);
            list.add(new Property(random));
        }

        return list;
    }
}

输出为

Property List...
[
  {
    "id": 43875,
    "info": "51-06 08:51:38",
    "createdOn": "Nov 6, 2018 8:51:38 AM",
    "dontCare": "N"
  },
  {
    "id": 30511,
    "info": "51-06 08:51:38",
    "createdOn": "Nov 6, 2018 8:51:38 AM",
    "dontCare": "N"
  },
  {
    "id": 17348,
    "info": "51-06 08:51:38",
    "createdOn": "Nov 6, 2018 8:51:38 AM",
    "dontCare": "Y"
  }
]

Answer 1

这就是我想要的这是输出

Custom adapters
{
  "Identification": "3",
  "properties": [
    {
      "Identifier": 16034,
      "Information": "43-06 02:43:48 (Y)"
    },
    {
      "Identifier": 46046,
      "Information": "43-06 02:43:48 (Y)"
    },
    {
      "Identifier": 91351,
      "Information": "43-06 02:43:48 (N)"
    }
  ]
}

这是我所缺少的代码。我仍然需要了解接线方式... 如果有人在评论中简要解释一下，那将非常有帮助

TypeToken<List<Property>> typeDescription = new TypeToken<List<Property>>() {};
JsonElement properties = context.serialize(src.getProperties(), typeDescription.getType());
outer.add("properties", properties);

完整代码（与TypeToken相关的代码，我来自另一个stackoverflow答案...）

package wrk;

import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer;
import com.google.gson.reflect.TypeToken;


public class Practice {

    public static void main (String args[])
    {
        JsonSerializer<Property> serializer4property = new JsonSerializer<Property>() {  
            @Override
            public JsonElement serialize(Property src, Type typeOfSrc, JsonSerializationContext context) {
                JsonObject property = new JsonObject();
                property.addProperty("Identifier", src.getId());
                property.addProperty("Information", src.getInfo() + " (" + src.getDontCare() + ")");
                return property;
            }
        };

        JsonSerializer<Outer> serializer4outer = new JsonSerializer<Outer>() {  
            @Override
            public JsonElement serialize(Outer src, Type typeOfSrc, JsonSerializationContext context) {
                JsonObject outer = new JsonObject();
                outer.addProperty("Identification", src.getName());

                TypeToken<List<Property>> typeDescription = new TypeToken<List<Property>>() {};
                JsonElement properties = context.serialize(src.getProperties(), typeDescription.getType());
                outer.add("properties", properties);

                return outer;
            }
        };

        System.out.println("An outer object...");
        Outer outer = giveMeAnOuter(3);

        System.out.println("");
        System.out.println("Custom adapters");
        GsonBuilder gsonBuilder = new GsonBuilder();
        gsonBuilder.registerTypeAdapter(Property.class, serializer4property);
        gsonBuilder.registerTypeAdapter(Outer.class, serializer4outer);
        Gson customGson = gsonBuilder.setPrettyPrinting().create();
        String customJSON = customGson.toJson(outer);  
        System.out.println (customJSON);

        /*
        System.out.println("\n");
        System.out.println ("Default behavior");
        GsonBuilder gsonBuilder2 = new GsonBuilder();
        Gson customGson2 = gsonBuilder2.setPrettyPrinting().create();
        String customJSON2 = customGson2.toJson(outer);  
        System.out.println (customJSON2);
        */

    }


    public static Outer giveMeAnOuter (int count)
    {
        Outer anOuter = new Outer();
        anOuter.setName(String.valueOf(count));

        ArrayList<Property> properties = new ArrayList<Property>();
        for (int i = 1; i <= count; i++) {
            int random = (int )(Math.random() * 98768 + 1);
            properties.add(new Property(random));
        }
        anOuter.setFirstProperty(properties.get(0));
        anOuter.setProperties(properties);

        return anOuter;
    }
}

Gson序列化无法使其正常工作

1 个答案: