Volley简介(三)

自定义Request:

我们先看下Request，是所有网络请求的基类。

支持的请求方式，包含post，get等请求方式，在定义请求方式中可以自己设定。

 /**     * Supported request methods.     */    public interface Method {        int DEPRECATED_GET_OR_POST = -1;        int GET = 0;        int POST = 1;        int PUT = 2;        int DELETE = 3;        int HEAD = 4;        int OPTIONS = 5;        int TRACE = 6;        int PATCH = 7;    }

构造方法，如果想修改请求方法就在这里设定：

 /**     * Creates a new request with the given URL and error listener.  Note that     * the normal response listener is not provided here as delivery of responses     * is provided by subclasses, who have a better idea of how to deliver an     * already-parsed response.     *     * @deprecated Use {@link #Request(int, String, com.android.volley.Response.ErrorListener)}.     */    @Deprecated    public Request(String url, Response.ErrorListener listener) {        this(Method.DEPRECATED_GET_OR_POST, url, listener);    }    /**     * Creates a new request with the given method (one of the values from {@link Method}),     * URL, and error listener.  Note that the normal response listener is not provided here as     * delivery of responses is provided by subclasses, who have a better idea of how to deliver     * an already-parsed response.     */    public Request(int method, String url, Response.ErrorListener listener) {        mMethod = method;        mUrl = url;        mErrorListener = listener;        setRetryPolicy(new DefaultRetryPolicy());        mDefaultTrafficStatsTag = TextUtils.isEmpty(url) ? 0: Uri.parse(url).getHost().hashCode();    }

监听处理，将网络请求交给你的监听处理。

  /**     * Subclasses must implement this to perform delivery of the parsed     * response to their listeners.  The given response is guaranteed to     * be non-null; responses that fail to parse are not delivered.     * @param response The parsed response returned by     * {@link #parseNetworkResponse(NetworkResponse)}     */    abstract protected void deliverResponse(T response);

处理请求的数据，返回的是数据是字节数组，然后根据你的需要处理数组：

/**     * Subclasses must implement this to perform delivery of the parsed     * response to their listeners.  The given response is guaranteed to     * be non-null; responses that fail to parse are not delivered.     * @param response The parsed response returned by     * {@link #parseNetworkResponse(NetworkResponse)}     */    abstract protected void deliverResponse(T response);

以上的方法是重写中，必要涉及到的，下面我们来看下StringRequest的代码：

public class StringRequest extends Request<String> {    private final Listener<String> mListener;    public StringRequest(int method, String url, Listener<String> listener,            ErrorListener errorListener) {        super(method, url, errorListener);        mListener = listener;    }    public StringRequest(String url, Listener<String> listener, ErrorListener errorListener) {        this(Method.GET, url, listener, errorListener);    }    @Override    protected void deliverResponse(String response) {        mListener.onResponse(response);    }    @Override    protected Response<String> parseNetworkResponse(NetworkResponse response) {        String parsed;        try {            parsed = new String(response.data, HttpHeaderParser.parseCharset(response.headers));        } catch (UnsupportedEncodingException e) {            parsed = new String(response.data);        }        return Response.success(parsed, HttpHeaderParser.parseCacheHeaders(response));    }}

ImageRequest ,JsonArrayRequest等，形式相同，所以我们自定义的请求也可以“借鉴”下这种写法。

public class DownLoadRequest extends Request {private Listener listener;/** 自定义的类 */private SimpleKeyBean simBean;/** * 构造：自定义请求参数 *  * @param url * @param sim * @param listener * @param errorlistener */public DownLoadRequest(String url, SimpleKeyBean sim, Listener listener,ErrorListener errorlistener) {super(Method.GET, url, errorlistener);// TODO Auto-generated constructor stubthis.listener = listener;this.simBean = sim;}@Overrideprotected void deliverResponse(Object res) {// TODO Auto-generated method stublistener.onResponse(res);}@Overrideprotected Response parseNetworkResponse(NetworkResponse response) {// TODO Auto-generated method stubDownBMBean bean;try {// 文件路径String path = DataProcess.dirPackage() + "/" + simBean.getSinger()+ "-" + simBean.getSong() + ".mp3";// 将字节数组保存为文件DataProcess.saveByteFile(response.data, path);// 创建返回的对象bean = new DownBMBean("suc", path);// 返回数据return Response.success(bean,HttpHeaderParser.parseCacheHeaders(response));} catch (Exception e) {// TODO: handle exceptionreturn Response.error(new ParseError(e));}}}

使用：

RequestQueue reQueue = Volley.newRequestQueue(this);//传递请求的参数DownLoadRequest request = new DownLoadRequest(path, simBean,new Response.Listener() {public void onResponse(Object bean) {// TODO Auto-generated method stub//获取返回的对象dwBean = (DownBMBean) bean;insHandler.sendEmptyMessage(1);}}, new Response.ErrorListener() {public void onErrorResponse(VolleyError arg0) {// TODO Auto-generated method stubinsHandler.sendEmptyMessage(2);}});reQueue.add(request);