1、JSONObject只是一种数据结构,可以理解为JSON格式的数据结构(key-value 结构),可以使用put方法给json对象添加元素。JSONObject可以很方便的转换成字符串,也可以很方便的把其他对象转换成JSONObject对象。
2、JSON(JavaScript Object Notation的首字母缩写)是一种轻量级数据交换格式,最常用于客户端 - 服务器通信。它既易于读/写,又与语言无关。JSON值可以是另一个JSON 对象,数组,数字,字符串,布尔值(true / false)或null。也是后端开发中经常要接触的一个一个类,将要数据封装成json然后传递给前端。
作者的项目demo
public void jsonTest(){//创建JSONObjectJSONObject json = new JSONObject();//添加属性json.put("username", "张三");json.put("password", "123");//打印System.out.println(json);//增加属性json.element("sex", "男");json.put("age", 18);System.out.println(json);//根据key返回输出System.out.println(json.get("sex"));}
public void beanConvertJson(){//定义对象Student stu = new Student("张三", "123456");//JavaBean对象转json字符串JSONObject jsonObject = JSONObject.fromObject(stu);System.out.println(jsonObject);//json字符串转为javaBean//定义json字符串String jsondata = "{\"username\":\"李四\", \"password\":\"123\"}";//转为json对象JSONObject json = JSONObject.fromObject(jsondata);//转为JavaBean对象,强转Student stu2 = (Student)JSONObject.toBean(json, Student.class);System.out.println(stu2.toString());}
// deepBean与json互转public void deepBeanConvertJson(){String jsondata = "{\"student\":{\"username\":\"李四\", \"password\":\"123\"},\"count\":20,\"name\":\"这是我的班级名\"}";//转为json对象JSONObject json = JSONObject.fromObject(jsondata);//转为JavaBean对象,强转Grade grade = (Grade)JSONObject.toBean(json, Grade.class);System.out.println(grade.toString());}
public void listConvertJson(){//定义list集合List list = new ArrayList();list.add(new Student("张三", "123"));list.add(new Student("李四", "456"));//list转json字符串JSONArray jsonArray = JSONArray.fromObject(list);System.out.println(jsonArray);//json字符串转listList list2 = new ArrayList();String jsondata = "[{\"password\":\"123\",\"username\":\"张三\"},{\"password\":\"456\",\"username\":\"李四\"}]";JSONArray jsonArray1 = JSONArray.fromObject(jsondata);for(int i = 0; i < jsonArray1.size(); i++) {JSONObject jsonObject2 = jsonArray1.getJSONObject(i);Student stu2 = (Student)JSONObject.toBean(jsonObject2, Student.class);list2.add(stu2);}System.out.println(list2);}
public void mapConvertJson(){//定义map集合Map map = new HashMap();map.put("1", new Student("张三", "123"));map.put("2", new Student("李四", "456"));//Map转json字符串JSONObject jsonMap = JSONObject.fromObject(map);System.out.println(jsonMap);//定义字符串map集合String jsondata = "{\"1\":{\"password\":\"123\",\"username\":\"张三\"},\"2\":{\"password\":\"456\",\"username\":\"李四\"}}";//map集合字符串转为mapMap map2 = (Map)JSONObject.fromObject(jsondata);Set set = map2.keySet();//定义迭代器,迭代输出Iterator ite = set.iterator();while(ite.hasNext()) {//取出一个字符串对象String key = (String)ite.next();//转为json格式JSONObject jsonObject = JSONObject.fromObject(map2.get(key));//转为对象Student stu = (Student)JSONObject.toBean(jsonObject, Student.class);System.out.println(key+" "+stu);}}
@AllArgsConstructor
@NoArgsConstructor
@Data
public class Student {private String username;private String password;
}
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Grade {private Student student;private Integer count;private String name;}
net.sf.json-lib json-lib 2.4 jdk15