Android：试图序列化...忘了注册类型适配器？“ [英] Android: Attempted to serialize ... Forgot to register a type adapter?"

问题描述

如何使用 Gson 将HashMap转换为JSON。

  class ClassData {
 public String jsonString; 
 public Class classType; 
} 
 HashMap< String，ClassData> map = new HashMap<>（）; 
 
 void convert（）{
 new Gson（）。toJson（map）; //抛出
} 
  

我得到下一个异常

试图序列化java.lang.Class：java.lang.String。忘记
注册一个类型的适配器？

解决方案

您需要实现自己的用于ClassData的自定义序列化程序，然后将其注册到您的Gson Builder。

  public class ClassDataSerializerExample {
 static class ClassData {
 public String jsonString; 
 public Class classType; 
 
 public ClassData（String jsonString，Class classType）{
 this.jsonString = jsonString; 
 this.classType = classType; 
} 
} 
 
 static class ClassDataSerializer实现了JsonSerializer< ClassData> {
 @Override 
 public JsonElement serialize（ClassData src，Type typeOfSrc，JsonSerializationContext context）{
 return new JsonPrimitive（src.jsonString）; 
 
 
 
 public static void main（String [] args）{
 GsonBuilder gsonBuilder = new GsonBuilder（）; 
 gsonBuilder.registerTypeAdapter（ClassData.class，new ClassDataSerializer（））; 
 
 HashMap< String，ClassData> map = new HashMap<>（）; 
 map.put（key，new ClassData（key，String.class））; 
 
 Gson gson = gsonBuilder.create（）; 
 String json = gson.toJson（map）; 
 
 System.out.println（json）; 
 
 
 
 
 
输出：{key：key} 
 
 
 
了解更多： https://sites.google.com/site/gson/gson-user-guide#TOC-Writing-a-Serializer  
 
How to convert HashMap to JSON using Gson.
class ClassData {
    public String jsonString;
    public Class classType;
}
HashMap<String, ClassData> map = new HashMap<>();

void convert(){
    new Gson().toJson(map); // throws
}
I am getting the next exception

  
Attempted to serialize java.lang.Class: java.lang.String. Forgot to
  register a type adapter?

解决方案
You need to implement your own custom serializer for ClassData, and then register it to your Gson Builder. 
public class ClassDataSerializerExample {
    static class ClassData {
        public String jsonString;
        public Class classType;

        public ClassData(String jsonString, Class classType) {
            this.jsonString = jsonString;
            this.classType = classType;
        }
    }

    static class ClassDataSerializer implements JsonSerializer<ClassData> {
        @Override
        public JsonElement serialize(ClassData src, Type typeOfSrc, JsonSerializationContext context) {
            return new JsonPrimitive(src.jsonString);
        }
    }

    public static void main(String[] args) {
        GsonBuilder gsonBuilder = new GsonBuilder();
        gsonBuilder.registerTypeAdapter(ClassData.class, new ClassDataSerializer());

        HashMap<String, ClassData> map = new HashMap<>();
        map.put("key", new ClassData("key", String.class));

        Gson gson = gsonBuilder.create();
        String json = gson.toJson(map);

        System.out.println(json);
    }
}
Output: {"key":"key"}

Read more: https://sites.google.com/site/gson/gson-user-guide#TOC-Writing-a-Serializer

                        
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