Google Volley使用之自定义

jopen 8年前

【工匠若水 http://blog.csdn.net/yanbober】 阅读前一篇《Google Volley使用之基础》 http://blog.csdn.net/yanbober/article/details/45307015

开源项目链接

Volley自定义 Android Developer文档

Volley主页：https://android.googlesource.com/platform/frameworks/volley

Volley仓库：git clone https://android.googlesource.com/platform/frameworks/volley

Volley GitHub Demo：在GitHub主页搜索Volley会有很多，不过建议阅读Android Developer文档。

背景知识

Most requests have ready-to-use implementations in the toolbox; if your response is a string, image, or JSON, you probably won’t need to implement a custom Request.

For cases where you do need to implement a custom request, this is all you need to do:

  • Extend the Request class, where represents the type of parsed response the request expects.
    So if your parsed response is a string, for example, create your custom request by extending Request[String].
    See the Volley toolbox classes StringRequest and ImageRequest for examples of extending Request[T].
  • Implement the abstract methods parseNetworkResponse() and deliverResponse(), described in more detail below.

正如官方牛逼的说法一样：

你要是请求的是string, image, or JSON还好办，有现成的，前一篇已经详细说明了。But你要是返回的不是这些呢？那就比较蛋疼，需要自定义。不过好的一点是Volley框架的扩展性非常好。所以如果需要customer的话你需要按照如下处理：

  • 继承Request[T]类，[T]就是你的响应数据格式。你可以在写customer的时候参考StringRequest实现。
  • 实现parseNetworkResponse() and deliverResponse()两个抽象方法。

在StringRequest中，deliverResponse()方法调用了mListener中的onResponse()方法，并将response内容传入。parseNetworkResponse()方法对服务器响应的数据进行解析，数据是字节的形式放在NetworkResponse的data变量中的，这里将数据取出然后组装成一个String，并传入Response的success()方法中。

开搞一个实现

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 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(String url, Class<T> clazz, Map<String, String> headers,              Listener<T> listener, ErrorListener errorListener) {          super(Method.GET, url, errorListener);          this.clazz = clazz;          this.headers = headers;          this.listener = listener;      }        @Override      public Map<String, String> getHeaders() throws AuthFailureError {          return headers != null ? headers : super.getHeaders();      }        @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));          }      }  }

这是官方的GSON的反馈解析实现。

public class XMLRequest extends Request<XmlPullParser> {          private final Listener<XmlPullParser> listener;          public XMLRequest(int method, String url, Listener<XmlPullParser> listener,                ErrorListener errorListener) {            super(method, url, errorListener);            this.listener = listener;        }          public XMLRequest(String url, Listener<XmlPullParser> listener, ErrorListener errorListener) {            this(Method.GET, url, listener, errorListener);        }          @Override       protected Response<XmlPullParser> parseNetworkResponse(NetworkResponse response) {            try {                String xmlString = new String(response.data,                        HttpHeaderParser.parseCharset(response.headers));                XmlPullParserFactory factory = XmlPullParserFactory.newInstance();                XmlPullParser xmlPullParser = factory.newPullParser();                xmlPullParser.setInput(new StringReader(xmlString));                return Response.success(xmlPullParser, HttpHeaderParser.parseCacheHeaders(response));            } catch (UnsupportedEncodingException e) {                return Response.error(new ParseError(e));            } catch (XmlPullParserException e) {                return Response.error(new ParseError(e));            }        }          @Override       protected void deliverResponse(XmlPullParser response) {            listener.onResponse(response);        }    }

这是一个XmlPullParser反馈解析的实现。

通过如上你会发现Volley框架不愧于是Google大牛搞的，连拓展自定义都这么方便，设计模式运用的出神入化，膜拜。

【工匠若水 http://blog.csdn.net/yanbober】 继续阅读《 Google Volley框架源码走读》 http://blog.csdn.net/yanbober/article/details/45307217

来自： http://blog.csdn.net//yanbober/article/details/45307099