HttpClient4.2.2的几个常用方法,登录之后访问页面有关问题,下载文件

HttpClient4.2.2的几个常用方法,登录之后访问页面问题,下载文件

在工作中要用到android，然后进行网络请求的时候，打算使用httpClient。

总结一下httpClient的一些基本使用。

版本是4.2.2。

使用这个版本的过程中，百度很多，结果都是出现的org.apache.commons.httpclient.这个包名，而不是我这里的org.apache.http.client.HttpClient----------前者版本是Commons HttpClient 3.x ，不是最新的版本HttpClient 4.×。

官网上面：

public void getUrl(String url, String encoding)throws ClientProtocolException, IOException {// 默认的client类。HttpClient client = new DefaultHttpClient();// 设置为get取连接的方式.HttpGet get = new HttpGet(url);// 得到返回的response.HttpResponse response = client.execute(get);// 得到返回的client里面的实体对象信息.HttpEntity entity = response.getEntity();if (entity != null) {System.out.println("内容编码是：" + entity.getContentEncoding());System.out.println("内容类型是：" + entity.getContentType());// 得到返回的主体内容.InputStream instream = entity.getContent();try {BufferedReader reader = new BufferedReader(new InputStreamReader(instream, encoding));System.out.println(reader.readLine());} catch (Exception e) {e.printStackTrace();} finally {instream.close();}}// 关闭连接.client.getConnectionManager().shutdown();}

2.基本的Post

   下面的params参数，是在表单里面提交的参数。


public void postUrlWithParams(String url, Map params, String encoding)throws Exception {DefaultHttpClient httpclient = new DefaultHttpClient();try {HttpPost httpost = new HttpPost(url);// 添加参数List<NameValuePair> nvps = new ArrayList<NameValuePair>();if (params != null && params.keySet().size() > 0) {Iterator iterator = params.entrySet().iterator();while (iterator.hasNext()) {Map.Entry entry = (Entry) iterator.next();nvps.add(new BasicNameValuePair((String) entry.getKey(),(String) entry.getValue()));}}httpost.setEntity(new UrlEncodedFormEntity(nvps, Consts.UTF_8));HttpResponse response = httpclient.execute(httpost);HttpEntity entity = response.getEntity();System.out.println("Login form get: " + response.getStatusLine()+ entity.getContent());dump(entity, encoding);System.out.println("Post logon cookies:");List<Cookie> cookies = httpclient.getCookieStore().getCookies();if (cookies.isEmpty()) {System.out.println("None");} else {for (int i = 0; i < cookies.size(); i++) {System.out.println("- " + cookies.get(i).toString());}}} finally {// 关闭请求httpclient.getConnectionManager().shutdown();}}

3。打印页面输出的小代码片段


private static void dump(HttpEntity entity, String encoding)throws IOException {BufferedReader br = new BufferedReader(new InputStreamReader(entity.getContent(), encoding));System.out.println(br.readLine());}

4.常见的登录session问题，需求:使用账户，密码登录系统之后，然后再访问页面不出错。

特别注意，下面的httpclient对象要使用一个，而不要在第二次访问的时候，重新new一个。至于如何保存这个第一步经过了验证的httpclient，有很多种方法实现。单例，系统全局变量（android 下面的Application），ThreadLocal变量等等。

       以及下面创建的httpClient要使用ThreadSafeClientConnManager对象！

   public String getSessionId(String url, Map params, String encoding,


String url2) throws Exception {DefaultHttpClient httpclient = new DefaultHttpClient(new ThreadSafeClientConnManager());try {HttpPost httpost = new HttpPost(url);// 添加参数List<NameValuePair> nvps = new ArrayList<NameValuePair>();if (params != null && params.keySet().size() > 0) {Iterator iterator = params.entrySet().iterator();while (iterator.hasNext()) {Map.Entry entry = (Entry) iterator.next();nvps.add(new BasicNameValuePair((String) entry.getKey(),(String) entry.getValue()));}}// 设置请求的编码格式httpost.setEntity(new UrlEncodedFormEntity(nvps, Consts.UTF_8));// 登录一遍httpclient.execute(httpost);// 然后再第二次请求普通的url即可。httpost = new HttpPost(url2);BasicResponseHandler responseHandler = new BasicResponseHandler();System.out.println(httpclient.execute(httpost, responseHandler));} finally {// 关闭请求httpclient.getConnectionManager().shutdown();}return "";}

5.下载文件，例如mp3等等。


//第一个参数，网络连接；第二个参数，保存到本地文件的地址public void getFile(String url, String fileName) {HttpClient httpClient = new DefaultHttpClient();HttpGet get = new HttpGet(url);try {ResponseHandler<byte[]> handler = new ResponseHandler<byte[]>() {public byte[] handleResponse(HttpResponse response)throws ClientProtocolException, IOException {HttpEntity entity = response.getEntity();if (entity != null) {return EntityUtils.toByteArray(entity);} else {return null;}}};byte[] charts = httpClient.execute(get, handler);FileOutputStream out = new FileOutputStream(fileName);out.write(charts);out.close();} catch (Exception e) {e.printStackTrace();} finally {httpClient.getConnectionManager().shutdown();}}

6.创建一个多线程环境下面可用的httpClient

（原文：http://blog.csdn.net/jiaoshi0531/article/details/6459468）


HttpParams params = new BasicHttpParams();//设置允许链接的做多链接数目ConnManagerParams.setMaxTotalConnections(params, 200);//设置超时时间.ConnManagerParams.setTimeout(params, 10000);//设置每个路由的最多链接数量是20ConnPerRouteBean connPerRoute = new ConnPerRouteBean(20);//设置到指定主机的路由的最多数量是50HttpHost localhost = new HttpHost("127.0.0.1",80);connPerRoute.setMaxForRoute(new HttpRoute(localhost), 50);ConnManagerParams.setMaxConnectionsPerRoute(params, connPerRoute);//设置链接使用的版本HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1);//设置链接使用的内容的编码HttpProtocolParams.setContentCharset(params,HTTP.DEFAULT_CONTENT_CHARSET);//是否希望可以继续使用.HttpProtocolParams.setUseExpectContinue(params, true);SchemeRegistry schemeRegistry = new SchemeRegistry();schemeRegistry.register(new Scheme("http",PlainSocketFactory.getSocketFactory(),80));schemeRegistry.register(new Scheme("https",SSLSocketFactory.getSocketFactory(),443));ClientConnectionManager cm = new ThreadSafeClientConnManager(params,schemeRegistry);httpClient = new DefaultHttpClient(cm, params);

7.实用的一个对象，http上下文，可以从这个对象里面取到一次请求相关的信息，例如request，response，代理主机等。


public static void getUrl(String url, String encoding)throws ClientProtocolException, IOException {// 设置为get取连接的方式.HttpGet get = new HttpGet(url);HttpContext localContext = new BasicHttpContext();// 得到返回的response.第二个参数，是上下文，很好的一个参数！httpclient.execute(get, localContext);// 从上下文中得到HttpConnection对象HttpConnection con = (HttpConnection) localContext.getAttribute(ExecutionContext.HTTP_CONNECTION);System.out.println("socket超时时间：" + con.getSocketTimeout());// 从上下文中得到HttpHost对象HttpHost target = (HttpHost) localContext.getAttribute(ExecutionContext.HTTP_TARGET_HOST);System.out.println("最终请求的目标:" + target.getHostName() + ":"+ target.getPort());// 从上下文中得到代理相关信息.HttpHost proxy = (HttpHost) localContext.getAttribute(ExecutionContext.HTTP_PROXY_HOST);if (proxy != null)System.out.println("代理主机的目标:" + proxy.getHostName() + ":"+ proxy.getPort());System.out.println("是否发送完毕:"+ localContext.getAttribute(ExecutionContext.HTTP_REQ_SENT));// 从上下文中得到HttpRequest对象HttpRequest request = (HttpRequest) localContext.getAttribute(ExecutionContext.HTTP_REQUEST);System.out.println("请求的版本:" + request.getProtocolVersion());Header[] headers = request.getAllHeaders();System.out.println("请求的头信息: ");for (Header h : headers) {System.out.println(h.getName() + "--" + h.getValue());}System.out.println("请求的链接:" + request.getRequestLine().getUri());// 从上下文中得到HttpResponse对象HttpResponse response = (HttpResponse) localContext.getAttribute(ExecutionContext.HTTP_RESPONSE);HttpEntity entity = response.getEntity();if (entity != null) {System.out.println("返回结果内容编码是：" + entity.getContentEncoding());System.out.println("返回结果内容类型是：" + entity.getContentType());dump(entity, encoding);}}

输出结果大致如下：


socket超时时间：0最终请求的目标:money.finance.sina.com.cn:-1是否发送完毕:true请求的版本:HTTP/1.1请求的头信息: Host--money.finance.sina.com.cnConnection--Keep-AliveUser-Agent--Apache-HttpClient/4.2.2 (java 1.5)请求的链接:/corp/go.php/vFD_BalanceSheet/stockid/600031/ctrl/part/displaytype/4.phtml返回结果内容编码是：null返回结果内容类型是：Content-Type: text/html

8.设置代理


//String hostIp代理主机ip,int port 代理端口HttpHost proxy = new HttpHost(hostIp, port);// 设置代理主机.httpclient.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY,proxy);

9.设置保持链接时间


//在服务端设置一个保持持久连接的特性.//HTTP服务器配置了会取消在一定时间内没有活动的链接，以节省系统的持久性链接资源.httpClient.setKeepAliveStrategy(new ConnectionKeepAliveStrategy() {public long getKeepAliveDuration(HttpResponse response,HttpContext context) {HeaderElementIterator it = new BasicHeaderElementIterator(response.headerIterator(HTTP.CONN_KEEP_ALIVE));while (it.hasNext()) {HeaderElement he = it.nextElement();String param = he.getName();String value = he.getValue();if (value != null && param.equalsIgnoreCase("timeout")) {try {return Long.parseLong(value) * 1000;} catch (Exception e) {}}}HttpHost target = (HttpHost)context.getAttribute(ExecutionContext.HTTP_TARGET_HOST);if("www.baidu.com".equalsIgnoreCase(target.getHostName())){return 5*1000;}elsereturn 30*1000; } });

转账注明出处：http://renjie120.iteye.com/blog/1727933