Gson 解析小技巧

解析 List 的时候官方的使用:

List dims=gson.fromJson(json,new TypeToken>(){}.getType());

使用TypeToken 匿名内部类的方式.获取到匿名内部类定义的泛型.

当我们封装一个工具类的时候,解析 List 的时候不可避免要传递一个 TypeToken 匿名内部类的进来.
有什么办法只传递Dim 而不用写很长的 TypeToken 呢?
方式其实很简单,就是为 Gson 构造一个正确的 Type 给它.

TypeFactory是一个工具类简单封装.

/**
 * Created by dim on 16/5/27.
 */
public class TypeFactory {

    public static Type $List(Type type) {
        return $Gson$Types.newParameterizedTypeWithOwner(null, List.class, type);
    }

    public static Type $Set(Type type) {
        return $Gson$Types.newParameterizedTypeWithOwner(null, Set.class, type);
    }

    public static Type $HashMap(Type type, Type type2) {
        return $Gson$Types.newParameterizedTypeWithOwner(null, HashMap.class, type, type2);
    }

    public static Type $Map(Type type, Type type2) {
        return $Gson$Types.newParameterizedTypeWithOwner(null, Map.class, type, type2);
    }

    public static Type $Parameterized(Type ownerType, Type rawType, Type... typeArguments) {
        return $Gson$Types.newParameterizedTypeWithOwner(ownerType, rawType, typeArguments);
    }

    public static Type $Array(Type type) {
        return $Gson$Types.arrayOf(type);
    }

    public static Type $SubtypeOf(Type type) {
        return $Gson$Types.subtypeOf(type);
    }

    public static Type $SupertypeOf(Type type) {
        return $Gson$Types.supertypeOf(type);
    }
}

使用:

List dims = gson.fromJson(json, TypeFactory.$List(Dim.class));

再使用静态导入方法:

import static com.dim.TypeFactory.*;
...

List dims = gson.fromJson(json, $List(Dim.class));
...

一些复杂的泛型

List dims = gson.fromJson(json, $List(Dim.class));
List> dimss= gson.fromJson(json,$List($List(Dim.class)));
Dim[] dimArray=gson.fromJson(json,$Array(Dim.class));
Set dimSet=gson.fromJson(json,$Set(Dim.class));
Map dimMap=gson.fromJson(json,$Map(String.class,Dim.class));
Map> dimsMap=gson.fromJson(json,$Map(String.class,$List(Dim.class)));