1.FinalHttp是什么 ：FinalHttp 对 HttpClient再次封装，最简洁的就是增加了许多回调的方法，对Get 和 Post 请求进行了简化。另外一点就是FinalHttp加入线程池操作，默认的Http请求池连接为3。下面是为FinalHttp可配置的操作。
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FinalHttp finalHttp = new FinalHttp();finalHttp.addHeader("Accept-Charset", "UTF-8");//配置http请求头finalHttp.configCharset("UTF-8");finalHttp.configCookieStore(null);finalHttp.configRequestExecutionRetryCount(3);//请求错误重试次数finalHttp.configSSLSocketFactory(null);finalHttp.configTimeout(5000);//超时时间finalHttp.configUserAgent("Mozilla/5.0");//配置客户端信息 |
2.FinalHttp 之 Get
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//------------------get 请求----------------------- public void get( String url, AjaxCallBack<? extends Object> callBack) { get( url, null, callBack); } public void get( String url, AjaxParams params, AjaxCallBack<? extends Object> callBack) { sendRequest(httpClient, httpContext, new HttpGet(getUrlWithQueryString(url, params)), null, callBack); } public void get( String url, Header[] headers, AjaxParams params, AjaxCallBack<? extends Object> callBack) { HttpUriRequest request = new HttpGet(getUrlWithQueryString(url, params)); if(headers != null) request.setHeaders(headers); sendRequest(httpClient, httpContext, request, null, callBack); } |
三个方法的却别在于：第二个增加了参数。第三个增加了http header。，此处，AjaxParams 是一个 map集合。来看看 sendRequest方法。
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protected <T> void sendRequest(DefaultHttpClient client, HttpContext httpContext, HttpUriRequest uriRequest, String contentType, AjaxCallBack<T> ajaxCallBack) { if(contentType != null) { uriRequest.addHeader("Content-Type", contentType); } new HttpHandler<T>(client, httpContext, ajaxCallBack,charset) .executeOnExecutor(executor, uriRequest); } |
这里面 直接调用了一个类HttpHandler的executeOnExecutor方法，传入了一个重要的参数executor。看看这个类：HttpHandler
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public class HttpHandler <T> extends AsyncTask<Object, Object, Object> implements EntityCallBack{ private final AjaxCallBack<T> callback; private int executionCount = 0; public HttpHandler(AbstractHttpClient client, HttpContext context, AjaxCallBack<T> callback,String charset) { this.client = client; this.context = context; this.callback = callback; this.charset = charset; } |
这个类继承了 AsyncTask，这个 AsyncTask是作者 自定义的，它相对于android 自带的 AsyncTask：修改了线程池属性，让并发线程按顺序执行。之前好像有人提到使用 afinal 加载图片是一个一个加载的，原因可能就在这里了。
这个类还实现了自定义的一个接口，里面的这个方法是我们回调的方法：
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public interface EntityCallBack { public void callBack(long count,long current,boolean mustNoticeUI);} |
这表明了HttpHandler 是一个异步加载类，我精简掉方法中暂时不用的代码，很显然，他的异步方法应该在 这个方法中执行doInBackground：
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@Override protected Object doInBackground(Object... params) { try { publishProgress(UPDATE_START); // 开始 makeRequestWithRetries((HttpUriRequest)params[0]);//调用 } catch (IOException e) { publishProgress(UPDATE_FAILURE,e,0,e.getMessage()); // 结束 } return null; } |
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private void makeRequestWithRetries(HttpUriRequest request) throws IOException { boolean retry = true; IOException cause = null; HttpRequestRetryHandler retryHandler = client.getHttpRequestRetryHandler(); while (retry) { try { if (!isCancelled()) { [color=Red]HttpResponse response = client.execute(request, context);[/color]//这里就开始执行了 if (!isCancelled()) { handleResponse(response); } } return; } catch (UnknownHostException e) { publishProgress(UPDATE_FAILURE,e,0,"unknownHostException：can't resolve host"); return; } catch (IOException e) { cause = e; retry = retryHandler.retryRequest(cause, ++executionCount,context); } catch (NullPointerException e) { cause = new IOException("NPE in HttpClient" + e.getMessage()); retry = retryHandler.retryRequest(cause, ++executionCount,context); }catch (Exception e) { cause = new IOException("Exception" + e.getMessage()); retry = retryHandler.retryRequest(cause, ++executionCount,context); } } if(cause!=null) throw cause; else throw new IOException("未知网络错误"); } |
HttpResponse response = client.execute(request, context);这就开始执行了。
retry = retryHandler.retryRequest(cause, ++executionCount,context);这里出现异常执行一次，次数加一次。直到你设置的次数超过为止，retryHandler 就会直接返回false 中断 while(retry)
http://www.kwstu.com/ArticleView/419895180_2013925101126966