Java Gson 简要笔记

Gson是Google开发的Java比较好用的 Json工具。

使用挺简单，假设有个类:

 class Runner {
     int attr;
     String name;
     public Runner(int attr, String name)   {
         this.attr = attr;
         this.name = name;
     }
 }

Object -> JSON （关键 line 3）:

 Gson gson = new Gson();
 Runner runner = new Runner(3, "lhfcws");
 String jsonStr = gson.toJson(runner);
 System.out.println(jsonStr);

JSON -> Object:

 Gson gson = new Gson();
 String jsonStr = "....";
 Runner runner = gson.fromJson(jsonStr, Runner.class);

当遇到泛型的时候，fromJson最好使用另一种方法，TypeToken。不然有时会把对象识别成LinkedHashMap结构：

 Gson gson = new Gson();
 String jsonStr = "....";
 List<Runner> runnerList = gson.fromJson(jsonStr, new TypeToken<List<Runner>>(){}.getType());