使用org.json包将JSON对象转换为Java bean

Question

I have Java bean class, for example:

public class User  implements Serializable{
    protected String Name        = null;
    protected String Password    = null;
    // ...
}  

I can convert it easily to org.json object using

User u = new User();
u.setName("AAA");
u.setPassword("123");
JSONObject jo = new JSONObject(u);

Is it way to convert JSONObject to Java bean class?

Answer 1

There's an existing library that implements the reflection method to convert JSON Object to Java bean, called Gson .

Using it you can convert JSON text (the result of calling jo.toString() in your code) back to the User type:

User user = new Gson().fromJson(jSONObjectAsString, User.class);

This library also implements a toJson() method, so it should be possible for you to replace your use of the json.org implementation with Gson for all cases.

Answer 2

There is no built-in way to do that using the json.org library.

Depending on your needs, you can either

1. write a fromJSONObject() method for each of your beans, which uses JSONObject#has() and JSONObject#get*() to get the needed values and handle any type problems.
2. Write a global method which uses JSONObject#names() and reflection to populate a bean instance with data from a JSONObject. This is not difficult, but could be too heavy lifting if all you need it to use it with a couple of bean classes.

Answer 3

public static Object toBean(JSONObject jobject, Object object) {
    for (Field field : object.getClass.getDeclaredFields()) {
        field.set(object, jobject.getString(field.getName()));
    }
}

Call:

User user = (User) toBean(jo, new User());