Gson工具 基本API

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

class Util_JsonToObject{
public static  T jsonToObject(String jsonstring, Class type){ // 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"}]}		 
	}