如何使用GSON将JSON字符串转换为对象集合？

Question

我有以下课程:

public class UserObject implements Serializable
{
    public Integer id;
    public String name;
    public String phoneno;

    public UserObject()
    {
        this.id = new Integer(0);
        this.name = "";
        this.phoneno = "";
   }
}

我有一个json像下面这样的字符串:

[
    {
        "id": 1,
        "name": "First Name",
        "phoneno": "0123452",
    },
    {
        "id": 2,
        "name": "Second Name",
        "phoneno": "0123452",
    },
    {
        "id": 3,
        "name": "Third Name",
        "phoneno": "0123455",
   }
]

我可以很容易地从转换Collection的UserObject到JSON使用下面的代码:

Collection users = new Vector();
UserObject userObj = new UserObject();

userObj.id=1; userObj.name="First Name"; userObj.phoneno="0123451";
users.add(userObj);
userObj.id=2; userObj.name="Second Name"; userObj.phoneno="0123452";
users.add(userObj);
userObj.id=3; userObj.name="Second Name"; userObj.phoneno="0123455";
users.add(userObj);

Gson gson = new Gson();
String json = gson.toJson(users);

但我不知道如何将转换JSON string到collection的objects？我发现我可以使用,gson.fromJson()但不知道如何使用Collection.请帮忙.

Answer 1

给定此 JSON，您的包装类应如下所示：

public class Data {
    private List<User> users;
    // +getters/setters
}

public class User {
    private String name;
    private String email;
    private List<User> friends;
    // +getters/setters
}

然后将其转换，使用

Data data = gson.fromJson(this.json, Data.class);

要获得用户，请使用

List<User> users = data.getUsers();

Answer 2

下面的代码可以让你得到Collection的UserObject

Type token = new TypeToken<Collection<UserObject>>() {}.getType();
Collection<UserObject> result = gson.fromJson(json, token);

此外,请注意json问题中提供的内容无效,因为phoneno字段后面有一个额外的逗号.这是正确的:

[
    {
        "id": 1,
        "name": "First Name",
        "phoneno": "0123452"
    },
    {
        "id": 2,
        "name": "Second Name",
        "phoneno": "0123452"
    },
    {
        "id": 3,
        "name": "Third Name",
        "phoneno": "0123455"
    }
]