使用gson的tojson和fromjson实现对象和json的转换

Gson gson = new Gson(); // Or use new GsonBuilder().create();
     MyType target = new MyType();
     String json = gson.toJson(target); // serializes target to Json
     MyType target2 = gson.fromJson(json, MyType.class); // deserializes json into target2

Type listType = new TypeToken<List<String>>() {}.getType();
     List<String> target = new LinkedList<String>();
     target.add("blah");
     Gson gson = new Gson();
     String json = gson.toJson(target, listType);
     List<String> target2 = gson.fromJson(json, listType);

使用GsonBuilder创建gson对象
      Gson gson = new GsonBuilder()
         .registerTypeAdapter(Id.class, new IdTypeAdapter())
         .enableComplexMapKeySerialization()
         .serializeNulls()
         .setDateFormat(DateFormat.LONG)
         .setFieldNamingPolicy(FieldNamingPolicy.UPPER_CAMEL_CASE)
         .setPrettyPrinting()
         .setVersion(1.0)
         .create();
 
           Gson gson = new GsonBuilder()
       .register(Point.class, new MyPointTypeAdapter())
       .enableComplexMapKeySerialization()
       .create();

map对象转换成json对象

Gson gson = new GsonBuilder()
       .register(Point.class, new MyPointTypeAdapter())
       .enableComplexMapKeySerialization()
       .create();

Map<Point, String> original = new LinkedHashMap<Point, String>();
   original.put(new Point(5, 6), "a");
   original.put(new Point(8, 8), "b");
   System.out.println(gson.toJson(original, type));

The above code prints this JSON object:

{
     "(5,6)": "a",
     "(8,8)": "b"
   }

map对象转化成jsonArray对象：

Gson gson = new GsonBuilder().enableComplexMapKeySerialization().create();Map<Point, String> original = new LinkedHashMap<Point, String>();original.put(new Point(5, 6), "a");original.put(new Point(8, 8), "b");System.out.println(gson.toJson(original, type));The JSON output would look as follows:

   [[{"x": 5,"y": 6},"a"],[{"x": 8,"y": 8},"b"]]

JsonParser

parse方法将json类型的字符串，或者reader对象或者JsonReader对象解析成为jsonElement对象