首先引入相关jar包，
假设有一个实体类User
public class User{
private int id;
private String name;
}
然后通过fastJson进行类型转换
public static void main(String[] args){
String userString = "{"id":1,"name","lz"}";
JSONObject userJson = JSONObject.parseObject(userString);
User user = JSON.toJavaObject(userJson,User.class);
}