gson解析对象数组，使用泛型封装报错

Question

问题如下：

 public class App {

    public static void main(String[] args) {
        List<User> userList = new ArrayList<>();

        String json = "[{\"uid\":1,\"username\":\"user1\",\"password\":\"user1\",\"type\":\"普通\"},"
                + "{\"uid\":2,\"username\":\"user2\",\"password\":\"user2\",\"type\":\"普通\"},"
                + "{\"uid\":3,\"username\":\"user3\",\"password\":\"user3\",\"type\":\"普通\"}]";

        userList = jsonToBeanList(json, User.class);
        // 这个地方报错：java.lang.ClassCastException: com.google.gson.internal.LinkedTreeMap 
        // cannot be cast to com.hezhujun.match.pojo.User
        for (User user : userList) {
            System.out.println(user);
        }

    }

    public static <T> List<T> jsonToBeanList(String json, Class<T> clas) {
        Gson gson = new Gson();
        List<T> list = gson.fromJson(json, new TypeToken<List<T>>() {
        }.getType());
        // 这个地方可以正常打印
        for (T t : list) {
            System.out.println(t);
        }
        return list;
    }

    /* 运行之后控制台输出的信息

     {uid=1.0, username=user1, password=user1, type=普通}
    Exception in thread "main" {uid=2.0, username=user2, password=user2, type=普通}
    {uid=3.0, username=user3, password=user3, type=普通}
    java.lang.ClassCastException: com.google.gson.internal.LinkedTreeMap cannot be cast to com.hezhujun.match.pojo.User
    at com.hezhujun.match.util.App.main(App.java:22)


     */
}

Answer 1

http://www.w2bc.com/Article/22805