在android中使用GSON解析带有动态key和value的JSON

The most straightforward approach I can think of is to just treat the structure as a Map (of Map).

对于Gson，这相对容易做到，只要Map struct 是静态已知的，根的每个分支都有相同的深度，所有的东西都是String.

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

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

public class GsonFoo
{
  public static void main(String[] args) throws Exception
  {
    Gson gson = new Gson();
    Type mapType = new TypeToken<Map<String,Map<String, String>>>() {}.getType();
    Map<String,Map<String, String>> map = gson.fromJson(new FileReader("input.json"), mapType);
    System.out.println(map);

    // Get the count...
    int count = Integer.parseInt(map.get("0").get("count"));

    // Get each numbered entry...
    for (int i = 1; i <= count; i++)
    {
      System.out.println("Entry " + i + ":");
      Map<String, String> numberedEntry = map.get(String.valueOf(i));
      for (String key : numberedEntry.keySet())
        System.out.printf("key=%s, value=%s\n", key, numberedEntry.get(key));
    }

    // Get the routes...
    Map<String, String> routes = map.get("routes");

    // Get each route...
    System.out.println("Routes:");
    for (String key : routes.keySet())
      System.out.printf("key=%s, value=%s\n", key, routes.get(key));
  }
}

For more dynamic Map structure handling, I strongly suggest switching to use Jackson, instead of Gson, as Jackson will deserialize any JSON object of any arbitrary complexity into a Java Map, with just one simple line of code, and it will automatically retain the types of primitive values.

import java.io.File;
import java.util.Map;

import org.codehaus.jackson.map.ObjectMapper;

public class JacksonFoo
{
  public static void main(String[] args) throws Exception
  {
    ObjectMapper mapper = new ObjectMapper();
    Map map = mapper.readValue(new File("input.json"), Map.class);
    System.out.println(map);
  }
}

The same can be achieved with Gson, but it requires dozens of lines of code. (Plus, Gson has other shortcomings that make switching to Jackson well worth it.)