com.alibaba.fastjson.JSONArray cannot be cast to com.alibaba.fastjson.JSONObject

 

原來項目中使用的是jackson進行序列化，使用resttempldate調用后端服務（返回值用一個通用對象進行包裝，代碼在最后），代碼如下：

public List<Object> userInfo() {


        Map<String, String> data = new HashMap<>();
        data.put("id", super.getPara("id").trim());
        String url = "/***";
        ResponseData responseData = RestKit.getRestTemplate().postForObject(url, data, ResponseData.class);
        //List<Object> list = (List<Object>) responseData.getData();
        ArrayList<Object> list = (ArrayList<Object>) responseData.getData();
        LogObjectHolder.me().set(list.get(0));
        return list;
    }

但是需要將jackson轉換器由fastjson替代時，此時調用卻報com.alibaba.fastjson.JSONArray cannot be cast to com.alibaba.fastjson.JSONObject異常，原因是fastjson在使用resttemplate調用后返回的是jsonarray對象，雖然該對象也實現list接口，但是卻無法轉換成arraylist，所以上面代碼不能直接定死ArrayList對象，而是用List

List<Object> list = (List<Object>) responseData.getData();

返回值統一包裝對象代碼如下：

public class ResponseData<T> implements Serializable {

    public static final String DEFAULT_SUCCESS_MESSAGE = "請求成功";

    public static final String DEFAULT_ERROR_MESSAGE = "網絡異常";

    public static final Integer DEFAULT_SUCCESS_CODE = 200;

    public static final Integer DEFAULT_ERROR_CODE = 500;

    /**
     * 請求是否成功
     */
    private Boolean success;

    /**
     * 響應狀態碼
     */
    private Integer code;

    /**
     * 響應信息
     */
    private String message;

    /**
     * 響應對象
     */
    private T data;

    public ResponseData() {
    }

    public ResponseData(Boolean success, Integer code, String message, T data) {
        this.success = success;
        this.code = code;
        this.message = message;
        this.data = data;
    }
    

    public T getData() {
        return data;
    }

    public void setData(T data) {
        this.data = data;
    }
    

    public Boolean getSuccess() {
        return success;
    }

    public void setSuccess(Boolean success) {
        this.success = success;
    }

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public static SuccessResponseData success() {
        return new SuccessResponseData();
    }

    public static SuccessResponseData success(Object object) {
        return new SuccessResponseData(object);
    }

    public static SuccessResponseData success(Integer code, String message, Object object) {
        return new SuccessResponseData(code, message, object);
    }

    public static ErrorResponseData error(String message) {
        return new ErrorResponseData(message);
    }

    public static ErrorResponseData error(Integer code, String message) {
        return new ErrorResponseData(code, message);
    }

    public static ErrorResponseData error(Integer code, String message, Object object) {
        return new ErrorResponseData(code, message, object);
    }
}

另外，關於alibaba 的fastjson，還有個問題需要注意：

com.alibaba.fastjson.JSONArray cannot be cast to com.alibaba.fastjson.JSONObject
json中類型轉換問題，[{}]是錯誤的格式。如下面我的寫法：

JSONObject.parseObject("[{\"type\":\"slider\",\"show\":\"true\",\"start\":1,\"end\":100}]");

正確的寫法為：

JSONObject[] dataZoom = new JSONObject[]{JSONObject.parseObject("{\"type\":\"slider\",\"show\":\"true\",\"start\":1,\"end\":100}")};

參考文章：

https://blog.csdn.net/qq_33101355/article/details/80112179