xUtils是github上的一个Android开源工具项目,其中HttpUtils模块是处理网络连接部分,刚好最近想整理下Android网络编程知识,今天学习下xUtils中HttpUtils.
xUtils项目地址:https://github.com/wyouflf/xUtils
先看看分析的时序图,了解下基本的过程
![](//pubimage.360doc.com/wz/default.gif)
1. Activity创建HttpUtils对象
- HttpUtils http = new HttpUtils();
查看HttpUtils类的构造函数
- public HttpUtils() {
- this(HttpUtils.DEFAULT_CONN_TIMEOUT);
- }
-
- public HttpUtils(int connTimeout) {
- HttpParams params = new BasicHttpParams();
-
- ConnManagerParams.setTimeout(params, connTimeout);
- HttpConnectionParams.setSoTimeout(params, connTimeout);
- HttpConnectionParams.setConnectionTimeout(params, connTimeout);
-
- ConnManagerParams.setMaxConnectionsPerRoute(params, new ConnPerRouteBean(10));
- ConnManagerParams.setMaxTotalConnections(params, 10);
-
- HttpConnectionParams.setTcpNoDelay(params, true);
- HttpConnectionParams.setSocketBufferSize(params, 1024 * 8);
- HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1);
-
- SchemeRegistry schemeRegistry = new SchemeRegistry();
- schemeRegistry.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));
- schemeRegistry.register(new Scheme("https", DefaultSSLSocketFactory.getSocketFactory(), 443));
-
- httpClient = new DefaultHttpClient(<span style="font-family: Arial, Helvetica, sans-serif;">new ThreadSafeClientConnManager(params, schemeRegistry)</span>, params);
-
- httpClient.setHttpRequestRetryHandler(new RetryHandler(DEFAULT_RETRY_TIMES));
-
- httpClient.addRequestInterceptor(new HttpRequestInterceptor() {
- @Override
- public void process(org.apache.http.HttpRequest httpRequest, HttpContext httpContext) throws org.apache.http.HttpException, IOException {
- if (!httpRequest.containsHeader(HEADER_ACCEPT_ENCODING)) {
- httpRequest.addHeader(HEADER_ACCEPT_ENCODING, ENCODING_GZIP);
- }
- }
- });
-
- httpClient.addResponseInterceptor(new HttpResponseInterceptor() {
- @Override
- public void process(HttpResponse response, HttpContext httpContext) throws org.apache.http.HttpException, IOException {
- final HttpEntity entity = response.getEntity();
- if (entity == null) {
- return;
- }
- final Header encoding = entity.getContentEncoding();
- if (encoding != null) {
- for (HeaderElement element : encoding.getElements()) {
- if (element.getName().equalsIgnoreCase("gzip")) {
- response.setEntity(new GZipDecompressingEntity(response.getEntity()));
- return;
- }
- }
- }
- }
- });
- }
这里主要是设置HttpParams参数,然后创建httpClient对象。
注意这个类ThreadSafeClientConnManager,它主要是为了使用线程安全的连接管理来创建HttpClient。
不过这里就有个疑问了,之前看资料了解到一般创建HttpClient都是用的 单例模式,说是一个httpClient就相当于是一个小型的浏览器,如果创建多个httpClient就很消耗资源了,我看了这个开源项目给的demo,是创建一个请求就创建一个HttpClient, 到时跟作者联系看看是什么回事。
2.发送请求
- http.send(HttpRequest.HttpMethod.GET,
- "http://www.baidu.com",
- new RequestCallBack<String>() {
-
-
- @Override
- public void onStart() {
- resultText.setText("conn...");
- }
-
-
- @Override
- public void onLoading(long total, long current, boolean isUploading) {
- resultText.setText(current + "/" + total);
- }
-
-
- @Override
- public void onSuccess(ResponseInfo<String> responseInfo) {
- resultText.setText("response:" + responseInfo.result);
- }
-
-
-
-
- @Override
- public void onFailure(HttpException error, String msg) {
- resultText.setText(msg);
- }
- });
调用send方法发生请求,
HttpRequest.HttpMethod.GET指明请求的方式,
"http://www.baidu.com"请求的地址,
new RequestCallBack<String>()请求的回调函数,这里面四个方法方便开发者处理请求的各个阶段的结果。
3. http.send()
- public <T> HttpHandler<T> send(HttpRequest.HttpMethod method, String url,
- RequestCallBack<T> callBack) {
- return send(method, url, null, callBack);
- }
-
- public <T> HttpHandler<T> send(HttpRequest.HttpMethod method, String url, RequestParams params,
- RequestCallBack<T> callBack) {
- if (url == null) throw new IllegalArgumentException("url may not be null");
-
- HttpRequest request = new HttpRequest(method, url);
- return sendRequest(request, params, callBack);
- }
- private <T> HttpHandler<T> sendRequest(HttpRequest request, RequestParams params, RequestCallBack<T> callBack) {
-
- HttpHandler<T> handler = new HttpHandler<T>(httpClient, httpContext, responseTextCharset, callBack);
-
- handler.setExpiry(currentRequestExpiry);
- handler.setHttpRedirectHandler(httpRedirectHandler);
- request.setRequestParams(params, handler);
-
- handler.executeOnExecutor(executor, request);
- return handler;
- }
查看httpUtils的send函数,发现最后会调用sendRequest函数
在sendRequest里创建HttpHandler对象
4. HttpHandler
- HttpHandler<T> extends CompatibleAsyncTask<Object, Object, Void> implements RequestCallBackHandler
参看httpHandler发现它继承CompatibleAsyncTask
5.CompatibleAsyncTask
查看CompatibleAsyncTask ,发现它是A compatible AsyncTask for android2.2.你懂得
6.handler.executeOnExecutor(executor, request)
在第3步里创建完httpHandler后,调用handler.executeOnExecutor(executor, request),而通过第4步了解到httpHandler继承CompatiableAsyncTask, 就先去看看doInBackground里做了什么事情。
7.doInBackground(Object... params)
- //先处理传递进来的params
-
- this.publishProgress(UPDATE_START);
-
-
- lastUpdateTime = SystemClock.uptimeMillis();
-
-
- ResponseInfo<T> responseInfo = sendRequest(request);
- if (responseInfo != null) {
- this.publishProgress(UPDATE_SUCCESS, responseInfo);
- return null;
- }
先处理传递进来的params,调用publishProgress更新下当前的状态,然后调用sendRequest
8.sendRequest(HttpRequestBase request)
- private ResponseInfo<T> sendRequest(HttpRequestBase request) throws HttpException {
-
-
- HttpRequestRetryHandler retryHandler = client.getHttpRequestRetryHandler();
- while (true) {
-
- requestMethod = request.getMethod();
- if (HttpUtils.sHttpCache.isEnabled(requestMethod)) {
- String result = HttpUtils.sHttpCache.get(requestUrl);
- if (result != null) {
- return new ResponseInfo<T>(null, (T) result, true);
- }
- }
-
-
- ResponseInfo<T> responseInfo = null;
- if (!isCancelled()) {
- HttpResponse response = client.execute(request, context);
- responseInfo = handleResponse(response);
- }
- return responseInfo;
- } catch (Exception e) {
- exception = e;
- retry = retryHandler.retryRequest(exception, ++retriedCount, context);
- }
- if (!retry) {
- throw new HttpException(exception);
- }
- }
- }
这个方法仔细看看,
先获取下client.getHttpRequestRetryHandler(),获取retry的设置
- requestMethod = request.getMethod();
- if (HttpUtils.sHttpCache.isEnabled(requestMethod)) {
- String result = HttpUtils.sHttpCache.get(requestUrl);
- if (result != null) {
- return new ResponseInfo<T>(null, (T) result, true);
- }
- }
如果使用了缓存则通过requestUrl去httpCache去获取,获取到了则创建ResponseInfo对象
如果没有缓存
- HttpResponse response = client.execute(request, context);
- responseInfo = handleResponse(response);
调用httpClient执行http请求,获取到得结果交由handleResponse处理
如果之前的处理出现异常则
- retry = retryHandler.retryRequest(exception, ++retriedCount, context);
调用retry机制,直到有结果,或者超过retry的次数
9.handleResponse()
第8步的时候,如果client执行获取到结果则调用handleResponse(HttpResponse response)处理结果
- ResponseInfo<T> handleResponse(HttpResponse response) throws HttpException, IOException {
-
- StatusLine status = response.getStatusLine();
- int statusCode = status.getStatusCode();
- if (statusCode < 300) {
-
- result = mStringDownloadHandler.handleEntity(entity, this, charset);
- if (HttpUtils.sHttpCache.isEnabled(requestMethod)) {
- HttpUtils.sHttpCache.put(requestUrl, (String) result, expiry);
- }
-
- }
- return new ResponseInfo<T>(response, (T) result, false);
- } else if (statusCode == 301 || statusCode == 302) {
- if (httpRedirectHandler == null) {
- httpRedirectHandler = new DefaultHttpRedirectHandler();
- }
- HttpRequestBase request = httpRedirectHandler.getDirectRequest(response);
- if (request != null) {
- return this.sendRequest(request);
- }
- }
- return null;
- }
这个方法主要根据返回的statuscode处理,<300将结果存在HttpCache里,301或者302则处理重定向
10.publishProgress(UPDATE_SUCCESS, responseInfo)
在获得ResponseInfo后,调用 publishProgress(UPDATE_SUCCESS, responseInfo)方法,最后会调用onProgressUpdate方法
- protected void onProgressUpdate(Object... values) {
- case UPDATE_SUCCESS:
- if (values.length != 2) return;
- this.state = State.SUCCESS;
- callback.onSuccess((ResponseInfo<T>) values[1]);
- break;
- default:
- break;
- }
- }
这onProgressUpdate里发现最终调用第2步传进来的callback
整个的调用过程基本上是这样。
1.创建httputils时创建httpClient,调用send发送请求
2. 调用send时,创建httpHandler,此类继承CompatibleAsyncTask
3.在httpHandler的doInBackground真正的处理http请求,此时会判断是否有缓存,获取结果后,通过回调处理结果