教程] 《开源框架-Afinal》之FinalHttp 01一步一脚

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

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