錯誤資訊
Exception in thread "main" java.lang.ClassCastException: com.alibaba.fastjson.JSONObject cannot be cast to com.xh.demo.UserDO
泛性類
@Data
public class ResultSetDTO<T> {
private Integer totalSize;
private Integer count;
private List<T> records;
}
物體類
@Data
public class UserDO {
private String id;
private String name;
}
Demo測驗
public class AppDemo {
public static void main(String[] args) {
ResultSetDTO<UserDO> resultSetDTO = new ResultSetDTO<UserDO>();
resultSetDTO.setTotalSize(10);
resultSetDTO.setCount(10);
List<UserDO> list = new ArrayList<>();
UserDO userDO = null;
for (int i = 10000; i < 10003; i++) {
userDO = new UserDO();
userDO.setId(i + "");
userDO.setName("TEST_" + i);
list.add(userDO);
}
resultSetDTO.setRecords(list);
String jsonString = JSON.toJSONString(resultSetDTO);
System.out.println(jsonString);
ResultSetDTO<XsyUserDO> resultSet = JSON.parseObject(jsonString, ResultSetDTO.class);
List<UserDO> records = resultSet.getRecords();
// 轉換是報例外
for (UserDO user : records) {
System.out.println(user.getName());
}
}
debuge 除錯時發現 resultSet.getRecords(); 回傳的是 ArrayList<JSONObject> 型別，不是 ArrayList<UserDO> 型別，由于型別參考必須強制指定目標物件，因此違背了 FastJson 規范，所以報：Exception in thread "main" java.lang.ClassCastException: com.alibaba.fastjson.JSONObject cannot be cast to com.xh.demo.UserDO，
解決方法
// 方法一
JSONObject parseObject = JSON.parseObject(jsonString);
List<UserDO> records = JSON.parseArray(parseObject.getString("records"), UserDO.class);
for (UserDO user : records) {
System.out.println(user.getName());
}
// 方法二
ResultSetDTO<XsyUserDO> resultSet = JSON.parseObject(jsonString, ResultSetDTO.class);
List<UserDO> records = JSONObject.parseArray(resultSet.getRecords().toString(), UserDO.class);
for (UserDO user : records) {
System.out.println(user.getName());
}
// 方法三
ResultSetDTO<XsyUserDO> resultSet = JSON.parseObject(jsonString, new TypeReference<ResultSetDTO<UserDO>>(){});
List<UserDO> records = resultSet.getRecords();
for (UserDO user : records){
System.out.println(user.getName());}
}
———————————
如有不足請留言指正
相互學習，共同進步
轉載請註明出處，本文鏈接：https://www.uj5u.com/qita/226637.html
標籤：其他