json学习(一)

json的存在有三种结构：

对象：{"name":"LiLei","age":25}

数组：比如：[{"name":"LiLei","age":25},{"name":"Tom","age":25}]

值：{"name":"LiLei", "birthday":{"month":8,"day":26}}，类似于对象嵌套对象.

一、

1.简单的解析json字符串——根据json中的键得到它的值

String name = jsonObject.getString("name");
int num = jsonObject.getInt("age");

2.将json字符串转换为java对象

JSONObject obj = new JSONObject().fromObject(jsonStr);//将json字符串转换为json对象
Person jb = (Person)JSONObject.toBean(obj,Person.class);//将建json对象转换为Person对象

3.将java对象转换为json字符串

JSONObject json = JSONObject.fromObject(obj);//将java对象转换为json对象
String str = json.toString();//将json对象转换为字符串

二、json 与常见的类型之间的转换

//list转json
List list=new ArrayList();
list.add("1");
list.add("2");
JsonArray json=JsonArray.fromObject(list)

//map转json
Map map = new HashMap();
map.put("欧尼", "json");
map.put("听我", Boolean.TRUE);
map.put("three", new Integer(1));
JSONObject json = JSONObject.fromObject(map);

//Bean转成json代码
JsonBean jb=new JsonBean()
JSONObject jsonObject = JSONObject.fromObject(jb);

//数组转json
int [] arr = new int[] { 1,2,3};
JSONArray jsonarray = JSONArray.fromObject(arr);

//字符串转json
JSONArray jsonarr = JSONArray.fromObject("['json','is','easy']" );

String jsonStr =   "{\"id\": 2," + 
                           " \"title\": \"json title\", " + 
                           "\"config\": {" +
                           "\"name\": 34," +
                           "\"type\": 35," +
                           "}, \"class\": [" +
                           "\"one\", \"two\", \"three\"" +
                           "]}";
         //转换成为JSONObject对象
 JSONObject jsonObj = new JSONObject(jsonStr);

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