java - 如何将android volley gson请求解析为对象列表/集合

Question

我正在尝试使用 android volley 发出 Gson 请求。目前它工作正常，我很高兴。但是，为什么我尝试获取 List<> 或对象集合，我的代码不再有效。

当前代码:

public class ReviewModel 
{
  public long Id;
  public Strring Description;
}

这里是我如何使用我的 gson 类:

    GsonRequest<ReviewModel> jsObjRequest = new GsonRequest<ReviewModel>(Request.Method.GET,
            url, ReviewModel.class, new Response.Listener<ReviewModel>() {
                @Override
                public void onResponse(ReviewModel response) {
                    ReviewsHandleOkResponse(response);
                }

            }, new ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    ReviewsHandleErrorResponse(error);
                }
            });
    Network.getInstance(getActivity()).addToRequestQueue(jsObjRequest);
}

这是我的 Volley GSON 请求类:

public class GsonRequest<T> extends Request<T> {
private final Gson gson = new Gson();
private final Class<T> clazz;
private final Map<String, String> headers;
private final Map<String, String> params;
private final Listener<T> listener;

/**
 * Make a GET request and return a parsed object from JSON.
 * 
 * @param url
 *            URL of the request to make
 * @param clazz
 *            Relevant class object, for Gson's reflection
 * @param headers
 *            Map of request headers
 */
public GsonRequest(int method, String url, Class<T> clazz,
        Map<String, String> headers, Map<String, String> params,
        Listener<T> listener, ErrorListener errorListener) {
    super(method, Network.getFullUrl(url), errorListener);
    this.clazz = clazz;
    this.headers = headers;
    this.params = params;
    this.listener = listener;
}

/**
 * Recieves header
 * 
 * @param method
 * @param url
 * @param clazz
 * @param params
 * @param listener
 * @param errorListener
 */
public GsonRequest(int method, String url, Class<T> clazz,
        Map<String, String> params, Listener<T> listener,
        ErrorListener errorListener) {
    super(method, Network.getFullUrl(url), errorListener);
    this.clazz = clazz;
    this.headers = new HashMap<String, String>();
    this.params = params;
    this.listener = listener;
}

/**
 * No params or headers
 * 
 * @param method
 * @param url
 * @param clazz
 * @param listener
 * @param errorListener
 */
public GsonRequest(int method, String url, Class<T> clazz,
        Listener<T> listener, ErrorListener errorListener) {
    super(method, Network.getFullUrl(url), errorListener);
    this.clazz = clazz;
    this.headers = new HashMap<String, String>();
    this.params = new HashMap<String, String>();
    this.listener = listener;
}

@Override
public Map<String, String> getHeaders() throws AuthFailureError {
    return headers != null ? headers : super.getHeaders();
}

@Override
public Map<String, String> getParams() throws AuthFailureError {
    return params != null ? params : super.getParams();
}

    @Override
protected void deliverResponse(T response) {
    listener.onResponse(response);
}

@Override
protected Response<T> parseNetworkResponse(NetworkResponse response) {
    try {
        String json = new String(response.data,
                HttpHeaderParser.parseCharset(response.headers));
        return Response.success(gson.fromJson(json, clazz),
                HttpHeaderParser.parseCacheHeaders(response));
    } catch (UnsupportedEncodingException e) {
        return Response.error(new ParseError(e));
    } catch (JsonSyntaxException e) {
        return Response.error(new ParseError(e));
    }
  }
}

然而，当我将其解析为 List<ReviewModel> 时我遇到编译错误。

根据我的研究，我需要做一些事情:

Type collectionType = new TypeToken<ArrayList<ReviewModel>>(){}.getType();      
    // api/v1/reviews/products/{productId}/{pageNumber}/{pageSize}
    String url = "api/v1/reviews/products/" + productId + "/" + currentPage + "/" + pageSize;
    GsonRequest<ArrayList<ReviewModel>> jsObjRequest = new GsonRequest<ArrayList<ReviewModel>>(Request.Method.GET,
            url, (Class<ArrayList<ReviewModel>>) collectionType, new Response.Listener<ArrayList<ReviewModel>>() {
                @Override
                public void onResponse(ArrayList<ReviewModel> response) {
                    ReviewsHandleOkResponse(response);
                }

            }, new ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    ReviewsHandleErrorResponse(error);
                }
            });
    Network.getInstance(getActivity()).addToRequestQueue(jsObjRequest);
}

但这给了我以下错误:

10-28 21:12:59.940: E/AndroidRuntime(28564): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.menu/com.menu.activities.ProductViewActivity}: java.lang.ClassCastException: com.google.gson.internal.$Gson$Types$ParameterizedTypeImpl cannot be cast to java.lang.Class

我是否需要修改我的 GsonRequest 类，并添加另一个不采用类型类的构造函数？

Answer 1

使用 YourClass[] 作为 Volley 请求中的对象列表。它解决了我的问题。以下代码应该可以帮助您:

GsonRequest<ReviewModel[]> jsObjRequest = new GsonRequest<ReviewModel[]>(Request.Method.GET,
        url, ReviewModel[].class, new Response.Listener<ReviewModel[]>() {
            @Override
            public void onResponse(ReviewModel[] response) {
                ReviewsHandleOkResponse(response);
            }
        }, new ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                ReviewsHandleErrorResponse(error);
            }
        });
Network.getInstance(getActivity()).addToRequestQueue(jsObjRequest);
}