用Gson解析JSON地图/词典？

Question

我需要解析一个看起来像这样的JSON响应:

{"key1": "value1", 
 "key2": "value2", 
 "key3": 
    {"childKey1": "childValue1", 
     "childKey2": "childValue2", 
     "childKey3": "childValue3" }
}

class Egg { 
    @SerializedName("key1")
    private String mKey1;

    @SerializedName("key2")
    private String mKey2;

    @SerializedName("key3")
    // ???
}

我正在阅读Gson文档,但无法弄清楚如何正确地将字典反序列化为Map.

Answer 1

Gson很容易将带有name:value对的JSON对象的反序列化处理成Java Map.

以下是使用原始问题中的JSON的示例.(此示例还演示了使用a FieldNamingStrategy来避免为每个字段指定序列化名称,前提是字段到元素名称映射是一致的.)

import java.io.FileReader;
import java.lang.reflect.Field;
import java.util.Map;

import com.google.gson.FieldNamingStrategy;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

public class Foo
{
  public static void main(String[] args) throws Exception
  {
    GsonBuilder gsonBuilder = new GsonBuilder();
    gsonBuilder.setFieldNamingStrategy(new MyFieldNamingStrategy());
    Gson gson = gsonBuilder.create();
    Egg egg = gson.fromJson(new FileReader("input.json"), Egg.class);
    System.out.println(gson.toJson(egg));
  }
}

class Egg
{
  private String mKey1;
  private String mKey2;
  private Map<String, String> mKey3;
}

class MyFieldNamingStrategy implements FieldNamingStrategy
{
  //Translates the Java field name into its JSON element name representation.
  @Override
  public String translateName(Field field)
  {
    String name = field.getName();
    char newFirstChar = Character.toLowerCase(name.charAt(1));
    return newFirstChar + name.substring(2);
  }
}