java学习第二阶段day8

摘要: JSON 字符串解析(官方JSON fastjson(阿里巴巴) GJson(谷歌))

JSON 字符串解析(官方JSON fastjson(阿里巴巴) GJson(谷歌))
需要导入 各自的第三方包

官方json解析

student2 类

public class Student2 {

public String name;
public int age;
public int id;
public Student2() {
// TODO Auto-generated constructor stub
}
public Student2(String name, int age, int id) {
super();
this.name = name;
this.age = age;
this.id = id;
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
public int getId() {
return id;
}
@Override
public String toString() {
return "Student2 [name=" + name + ", age=" + age + ", id=" + id + "]";
}

}
----------
JsonClass 类

public class JsonClass {
public static void main(String[] args) throws JSONException {
//官方JSON
//例子
//1、建一个student 类
Student2 student2 = new Student2("张三",12,9);
//2、
//1)用JSONObject 的构造方法 student类 必须要 get方法 本类返回属性
//对象 转换成json 字符串
JSONObject obj = new JSONObject(student2);
System.out.println(obj);
//2) 用JSONObject 的put 方法
//把 键 对应的 值 保存 起来(和map 一样)
JSONObject obj2 = new JSONObject();
obj2.put("name","王五");
obj2.put("id",4);
obj2.put("age",22);
System.out.println(obj2);

//结果 ：{"id":9,"name":"张三","age":12}
//{"dd":"王五","ff":4,"aa":22}

}
}
-----------------
JsonClass2 类

public class JsonClass2 {
public static void main(String[] args) throws JSONException {
Student2 stu = new Student2("哈哈",22,99);
JSONObject obj = new JSONObject(stu);
JSONObject obj2 = new JSONObject();
obj2.put("Student2", obj);
System.out.println(obj2);
//结果 : {"Student2":{"id":99,"name":"哈哈","age":22}}
}

}
--------------

JsonClass3

public class JsonClass3 {
public static void main(String[] args) {
Student2 stu1 = new Student2("李四",33,90);
Student2 stu2 = new Student2("李飞",21,88);
List<Student2> list = new ArrayList<Student2>();
list.add(stu1);
list.add(stu2);
JSONArray array = new JSONArray(list);
System.out.println(array);
//结果： [{"id":90,"name":"李四","age":33},{"id":88,"name":"李飞","age":21}]
}
}
--------------

JsonClass4

public class JsonClass3 {
public static void main(String[] args) throws JSONException {
Student2 stu1 = new Student2("李四",33,90);
Student2 stu2 = new Student2("李飞",21,88);
List<Student2> list = new ArrayList<Student2>();
list.add(stu1);
list.add(stu2);
JSONArray array = new JSONArray(list);
JSONObject obj = new JSONObject();
obj.put("Student2", array);
System.out.println(obj);
//结果：{"Student2":[{"id":90,"name":"李四","age":33},{"id":88,"name":"李飞","age":21}]}
}
}
------------------
Json 字符串 转换成为 对象

public class JsonClass5 {
public static void main(String[] args) throws JSONException {
Student2 stu1 = new Student2("李四",33,90);
JSONObject obj = new JSONObject(stu1);
Student2 stu = new Student2();
int id = obj.getInt("id");//通过id键获得整数值。
int age = obj.getInt("age");
String name = obj.getString("name");//通过名字为name的键获得字符串值
stu.setAge(age);
stu.setId(id);
stu.setName(name);
System.out.println(stu);
//结果:Student2 [name=李四, age=33, id=90]

}
}
----------------
JsonClass6

public class JsonClass3 {
public static void main(String[] args) throws JSONException {
Student2 stu1 = new Student2("李四",33,90);
JSONObject obj = new JSONObject(stu1);
JSONObject obj2 = new JSONObject();
//设置 Student2键 的值 为 obj -->stu1
obj2.put("Student2",obj);
//通过键Student2获得JSONObject对象
JSONObject obj3 = obj2.getJSONObject("Student2");
Student2 stu = new Student2();
int id = obj3.getInt("id");//通过id键获得整数值。
int age = obj3.getInt("age");
String name = obj3.getString("name");//通过名字为name的键获得字符串值
stu.setAge(age);
stu.setId(id);
stu.setName(name);
System.out.println(stu);
//结果:Student2 [name=李四, age=33, id=90]

}
}

--------------------------------------------------------------------

FastJson

FastJson 类

public class FastJson {
public static void main(String[] args){
Student2 stu = new Student2("哒哒",24,66);
JSONObject obj = new JSONObject(stu);
//结果:{"id":66,"name":"哒哒","age":24}
System.out.println(obj);
//把字符串 转换 成 对象
Student2 stu2 = JSON.parseObject(obj.toString(), Student2.class);
//结果:Student2 [name=哒哒, age=24, id=66]
System.out.println(stu2);
}
}
---------------
FastJson2 类

public class FastJson2 {
public static void main(String[] args){
Student2 stu = new Student2("哒哒",24,66);
Student2 stu2 = new Student2("滴滴",12,55);
List<Student2> list = new ArrayList<Student2>();
list.add(stu);
list.add(stu2);
JSONArray obj = new JSONArray(list);

//把字符串 转换 成 对象
List<Student2> list2 = JSON.parseArray(obj.toString(), Student2.class);
for(Student2 s : list2){
System.out.println(s);
//结果:Student2 [name=哒哒, age=24, id=66]
//Student2 [name=滴滴, age=12, id=55]
}
}
}
----------------------------------------------------------

Gson

public class Gson {
public static void main(String[] args){
Student2 stu = new Student2("哒哒",24,66);
JSONObject obj = new JSONObject(stu);
//创建一个Gson 对象
Gson gson = new Gson();
//调用 Gson 方法fromJson
Student2 stu2 = gson.fromJson(obj.toString(), Student2.class);
System.out.println(stu2);
//结果: Student2 [name=哒哒, age=24, id=66]
}
}
--------------