使用Volley和Gson:解析项目和项目列表

Question

关于Gson,我从未喜欢的一件事是你必须传递一个Class对象或一个TypeToken,如果你得到一个项目或一个项目列表.现在,当试图与Gson一起使用Volley时,这个问题仍然存在,我正在尝试创建一个可用于这两个方面的GsonRequest类.

我的解决方案非常难看,有两个不同的构造函数:一个获取Class<T>参数,另一个获取Type参数.然后,在parseNetworkResponse, gson.fromJson被称为与场中的任何一个,牢记一个必须null.

知道如何以更好的方式实现这一点吗？(我不喜欢有一个GsonRequest和GsonCollectionRequest几乎相同的课程)

我的代码,这里:

public class GsonRequest<T> extends Request<T> {

    private final Gson gson;
    private final Class<T> clazz;
    private final Type type;
    private final Listener<T> listener;
    private final Map<String, String> headers;
    private final Map<String, String> params;

    public GsonRequest(int method, String url, Gson gson, Class<T> clazz, Map<String, String> headers, Map<String, String> params, Listener<T> listener, ErrorListener errorListener) {
        super(method, url, errorListener);
        this.gson = gson;
        this.clazz = clazz;
        this.type = null;
        this.listener = listener;
        this.headers = headers;
        this.params = params;
    }

    public GsonRequest(int method, String url, Gson gson, Type type, Map<String, String> headers, Map<String, String> params, Listener<T> listener, ErrorListener errorListener) {
        super(method, url, errorListener);
        this.gson = gson;
        this.clazz = null;
        this.type = type;
        this.listener = listener;
        this.headers = headers;
        this.params = params;
    }

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

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

    @Override
    protected Response<T> parseNetworkResponse(NetworkResponse response) {
        try {

            if (this.clazz != null) {
                return Response.success(
                        this.gson.fromJson(new String(response.data, HttpHeaderParser.parseCharset(response.headers)), this.clazz),
                        HttpHeaderParser.parseCacheHeaders(response));
            } else {
                return (Response<T>) Response.success(
                        this.gson.fromJson(new String(response.data, HttpHeaderParser.parseCharset(response.headers)), this.type),
                        HttpHeaderParser.parseCacheHeaders(response));
            }

        } catch (JsonSyntaxException e) {
            e.printStackTrace();
            return Response.error(new ParseError(e));
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
            return Response.error(new ParseError(e));
        }
    }

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

}

Answer 1

我使用以下方法来解析 JSON 列表。首先不要在构造函数中发送 Class，而是从反射包中传递 Type 类。

我的课是这样的：

public class DownloadRequest<T> extends Request<T> {

private final Gson gson = new Gson();
private final Type type;
private final Map<String, String> params;
private final Response.Listener<T> listener;

public DownloadRequest(int method, String url, Map<String, String> params, Type type, Response.Listener<T> listener, Response.ErrorListener errorListener) {
    super(method, url, errorListener);
    this.type = type;
    this.params = params;
    this.listener = listener;
}

@Override
protected Response<T> parseNetworkResponse(NetworkResponse networkResponse) {

    try {
        String json = new String(networkResponse.data, HttpHeaderParser.parseCharset(networkResponse.headers));
        T parseObject = gson.fromJson(json, type);
        return Response.success(parseObject,HttpHeaderParser.parseCacheHeaders(networkResponse));
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }

    return null;
}

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

}

T parseObject = gson.fromJson(json, type);在调用 Request.success 方法之前设置该行很重要。