1、Map集合转JSON对象

创建一个Map集合；
新建json对象，并将Map引入json中。

public void demo1(){ //创建一个Map集合Map<String, String> map = new HashMap<>();map.put("1729210001","zhangsan");map.put("1729210002","lisi");map.put("1729210003","wangwu");//Map-->jsonJSONObject json = new JSONObject(map);//引入json对象System.out.println(json);//打印json：{"1729210003":"wangwu","1729210002":"lisi","1729210001":"zhangsan"}
}

2、普通对象转JSON对象

创建一个Person类和Address类（此处省略了有参/无参构造方法、get()方法、set()方法）；
新建Person对象和Address对象，并赋值；
新建json对象，并将对象引入json中。

public class Person { private String name;private int age;private Address address;
}public class Address { private String homeAddress;private String schoolAddress;
}@Test
public void demo2(){ //创建一个Person对象Person per =new Person();per.setName("zhangsan");per.setAge(23);Address add = new Address("杭州","宁波");per.setAddress(add);//Javabean-->jsonJSONObject json = new JSONObject(per);System.out.println(json);//打印json：{"address":{"schoolAddress":"宁波","homeAddress":"杭州"},"name":"zhangsan","age":23}
}

3、字符串转JSON对象

字符串类型的需要符合json格式；
将字符串引入到json对象中。

@Test
public void demo3(){ String str = "{\"name\":\"zhangsan\",\"age\":23}";//需要符合json格式JSONObject json = new JSONObject(str);System.out.println(json);
}