Gson工具 基本API

1. 通过json字符串给 初始化对象： Gson.fromJson(jsonString  string，Class<T> type )

class Util_JsonToObject{public static <T> T jsonToObject(String jsonstring, Class<T> type){ //<T> 含泛型的方法 并不是返回值；     Gson son = new Gson();    T t= son.fromJson(jsonstring,type );    return t;}}

应用1：

String jsonString = "{'name':'samuel.cai','age':23,'grade':{'course':'English','score':100,'level':'A'}}";                Student student = new JsonStudent();student  = Util_JsonToObject.jsonToObject(jsonString, JsonStudent.class);

2. 实例对象生成json字符串 : Gson.toJson(Object obj);

class Util_ObjectToJson{public static String ObjectToJson(Object obj){ Gson json = new Gson();return json.toJson(obj);}}

应用2：

public class ObjectToJson {     public static void main(String[] args) {     FatherJson.Kids kids = new FatherJson().new Kids("samuel","male",35);     FatherJson father = new FatherJson("蔡xx",69,kids);         String jsonString = Util_ObjectToJson.ObjectToJson(father);              System.out.println(jsonString); //{"name":"蔡xx","age":69,"kids":{"kids_name":"samuel","kids_sex":"male","kids_age":35}}     }}

3. Json对象：  不论是哪种创建形式，最小粒子都是 Key-value 形式； 和hashmap结构相似；

              //两种创建Jason对象形式：1  key-value; 2 array; 
//1.1 创建jason对象；添加属性：如果Key的内容重复 value就会被覆盖；
//1.2 key不能重复；value可以重复；
//1.3 key必须为string, value 5中类型：boolean,数字类型；字符串；字符型,jasonElement类型;

应用3.1  JsonObect创建：

JsonObject.addProperty(key,value)

public class GjsonCreate1 {public static void main(String[] args) { JsonObject jobject = new JsonObject();jobject.addProperty("name1", "水浒传");jobject.addProperty("name2", "红楼梦");jobject.addProperty("name3", "三国");jobject.addProperty("name4", "西游记"); jobject.addProperty("name5", true);jobject.addProperty("name6", 7);jobject.addProperty("name7", 'A');jobject.addProperty("name1", "水浒传~");System.out.println(jobject.toString());//{"name1":"水浒传~","name2":"红楼梦","name3":"三国","name4":"西游记","name5":true,"name6":7,"name7":"A"}}

应用3.2  JsonArray 创建：

JsonArray.add(JsonObject)

public class GjsonCreate2 {public static void main(String[] args) { //JsonArray:JSONArray，顾名思义是由JSONObject构成的数组，用  [ { } , { } , ......  , { } ]  来表示JsonArray array = new JsonArray();JsonObject sh = new JsonObject();JsonObject hlm = new JsonObject();JsonObject sg = new JsonObject();JsonObject xyj = new JsonObject();sh.addProperty("宋江", "老大");hlm.addProperty("贾宝玉","娘娘腔");sg.addProperty("刘备", "爱哭");xyj.addProperty("唐僧", "假正经");array.add(sh);array.add(hlm);array.add(sg);array.add(xyj);System.out.println(array.toString());//[{"宋江":"老大"},{"贾宝玉":"娘娘腔"},{"刘备":"爱哭"},{"唐僧":"假正经"}] 

jobject.add("名著主人公性格", array);// jobject引用的是3.1 中的对象System.out.println(jobject.toString());//{"name1":"水浒传~","name2":"红楼梦","name3":"三国","name4":"西游记","name5":true,"name6":7,"name7":"A","名著主人公性格":[{"宋江":"老大"},{"贾宝玉":"娘娘腔"},{"刘备":"爱哭"},{"唐僧":"假正经"}]} }