## 本節引言： > 在上一節中我們對HttpURLConnection進行了學習，本節到第二種方式：HttpClient，盡管被Google 棄用了，但是我們我們平時也可以拿HttpClient來抓下包，配合Jsoup解析網頁效果更佳！HttpClient 用于接收/發送Http請求/響應，但不緩存服務器響應，不執行HTML頁面潛入的JS代碼，不會對頁面內容 進行任何解析，處理！開始本節內容！ * * * ## 1.HttpClient使用流程 **基本流程**：  * * * ## 2.HttpClient使用示例 ### 1）使用HttpClient發送GET請求 直接貼下簡單的發送Get請求的代碼： ~~~ public class MainActivity extends Activity implements OnClickListener { private Button btnGet; private WebView wView; public static final int SHOW_DATA = 0X123; private String detail = ""; private Handler handler = new Handler() { public void handleMessage(Message msg) { if(msg.what == SHOW_DATA) { wView.loadDataWithBaseURL("",detail, "text/html","UTF-8",""); } }; }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initView(); setView(); } private void initView() { btnGet = (Button) findViewById(R.id.btnGet); wView = (WebView) findViewById(R.id.wView); } private void setView() { btnGet.setOnClickListener(this); wView.getSettings().setDomStorageEnabled(true); } @Override public void onClick(View v) { if (v.getId() == R.id.btnGet) { GetByHttpClient(); } } private void GetByHttpClient() { new Thread() { public void run() { try { HttpClient httpClient = new DefaultHttpClient(); HttpGet httpGet = new HttpGet("http://www.w3cschool.cc/python/python-tutorial.html"); HttpResponse httpResponse = httpClient.execute(httpGet); if (httpResponse.getStatusLine().getStatusCode() == 200) { HttpEntity entity = httpResponse.getEntity(); detail = EntityUtils.toString(entity, "utf-8"); handler.sendEmptyMessage(SHOW_DATA); } } catch (Exception e) { e.printStackTrace(); } }; }.start(); } } ~~~ **運行截圖**  另外，如果是帶有參數的GET請求的話，我們可以將參數放到一個List集合中，再對參數進行URL編碼， 最后和URL拼接下就好了： ~~~ List<BasicNameValuePair> params = new LinkedList<BasicNameValuePair>(); params.add(new BasicNameValuePair("user", "豬小弟")); params.add(new BasicNameValuePair("pawd", "123")); String param = URLEncodedUtils.format(params, "UTF-8"); HttpGet httpGet = new HttpGet("http://www.baidu.com"+"?"+param); ~~~ * * * ### 2）使用HttpClient發送POST請求 > POST請求比GET稍微復雜一點，創建完HttpPost對象后，通過NameValuePair集合來存儲等待提交 的參數，并將參數傳遞到UrlEncodedFormEntity中，最后調用setEntity(entity)完成， HttpClient.execute(HttpPost)即可；這里就不寫例子了，暫時沒找到Post的網站，又不想 自己寫個Servlet，So,直接貼核心代碼吧~ **核心代碼**: ~~~ private void PostByHttpClient(final String url) { new Thread() { public void run() { try{ HttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("user", "豬大哥")); params.add(new BasicNameValuePair("pawd", "123")); UrlEncodedFormEntity entity = new UrlEncodedFormEntity(params,"UTF-8"); httpPost.setEntity(entity); HttpResponse httpResponse = httpClient.execute(httpPost); if (httpResponse.getStatusLine().getStatusCode() == 200) { HttpEntity entity2 = httpResponse.getEntity(); detail = EntityUtils.toString(entity2, "utf-8"); handler.sendEmptyMessage(SHOW_DATA); } }catch(Exception e){e.printStackTrace();} }; }.start(); } ~~~ * * * ## 3.HttpClient抓數據示例(教務系統數據抓取) > 其實關于HttpClient的例子有很多，比如筆者曾經用它來抓學校教務系統上學生的課程表: 這就涉及到Cookie，模擬登陸的東西，說到抓數據(爬蟲)，一般我們是搭配著JSoup來解析 抓到數據的，有興趣可以自己查閱相關資料，這里貼下筆者畢設app里獲取網頁部分的關鍵 代碼！大家可以體會下： HttpClient可以通過下述代碼獲取與設置Cookie：?**HttpResponse loginResponse = new DefaultHttpClient().execute(getLogin);**?獲得Cookie:**cookie = loginResponse.getFirstHeader("Set-Cookie").getValue();**?請求時帶上Cookie**:httpPost.setHeader("Cookie", cookie);** ~~~ //獲得鏈接,模擬登錄的實現: public int getConnect(String user, String key) throws Exception { // 先發送get請求 獲取cookie值和__ViewState值 HttpGet getLogin = new HttpGet(true_url); // 第一步:主要的HTML: String loginhtml = ""; HttpResponse loginResponse = new DefaultHttpClient().execute(getLogin); if (loginResponse.getStatusLine().getStatusCode() == 200) { HttpEntity entity = loginResponse.getEntity(); loginhtml = EntityUtils.toString(entity); // 獲取響應的cookie值 cookie = loginResponse.getFirstHeader("Set-Cookie").getValue(); System.out.println("cookie= " + cookie); } // 第二步:模擬登錄 // 發送Post請求,禁止重定向 HttpPost httpPost = new HttpPost(true_url); httpPost.getParams().setParameter(ClientPNames.HANDLE_REDIRECTS, false); // 設置Post提交的頭信息的參數 httpPost.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko"); httpPost.setHeader("Referer", true_url); httpPost.setHeader("Cookie", cookie); // 設置請求數據 List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("__VIEWSTATE", getViewState(loginhtml)));// __VIEWSTATE參數，如果變化可以動態抓取獲取 params.add(new BasicNameValuePair("Button1", "")); params.add(new BasicNameValuePair("hidPdrs", "")); params.add(new BasicNameValuePair("hidsc", "")); params.add(new BasicNameValuePair("lbLanguage", "")); params.add(new BasicNameValuePair("RadioButtonList1", "%D1%A7%C9%FA")); params.add(new BasicNameValuePair("txtUserName", user)); params.add(new BasicNameValuePair("TextBox2", key)); params.add(new BasicNameValuePair("txtSecretCode", "")); // ( ╯□╰ )逗比正方,竟然不需要驗證碼 // 設置編碼方式,響應請求,獲取響應狀態碼: httpPost.setEntity(new UrlEncodedFormEntity(params, "gb2312")); HttpResponse response = new DefaultHttpClient().execute(httpPost); int Status = response.getStatusLine().getStatusCode(); if(Status == 200)return Status; System.out.println("Status= " + Status); // 重定向狀態碼為302 if (Status == 302 || Status == 301) { // 獲取頭部信息中Location的值 location = response.getFirstHeader("Location").getValue(); System.out.println(location); // 第三步:獲取管理信息的主頁面 // Get請求 HttpGet httpGet = new HttpGet(ip_url + location);// 帶上location地址訪問 httpGet.setHeader("Referer", true_url); httpGet.setHeader("Cookie", cookie); // 主頁的html mainhtml = ""; HttpResponse httpResponseget = new DefaultHttpClient() .execute(httpGet); if (httpResponseget.getStatusLine().getStatusCode() == 200) { HttpEntity entity = httpResponseget.getEntity(); mainhtml = EntityUtils.toString(entity); } } return Status; } ~~~ * * * ## 4.使用HttpPut發送Put請求 **示例代碼如下**： ~~~ public static int PutActCode(String actCode, String licPlate, Context mContext) { int resp = 0; String cookie = (String) SPUtils.get(mContext, "session", ""); HttpPut httpPut = new HttpPut(PUTACKCODE_URL); httpPut.setHeader("Cookie", cookie); try { List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("activation_code", actCode)); params.add(new BasicNameValuePair("license_plate", licPlate)); httpPut.setEntity(new UrlEncodedFormEntity(params, "UTF-8")); HttpResponse course_response = new DefaultHttpClient().execute(httpPut); if (course_response.getStatusLine().getStatusCode() == 200) { HttpEntity entity2 = course_response.getEntity(); JSONObject jObject = new JSONObject(EntityUtils.toString(entity2)); resp = Integer.parseInt(jObject.getString("status_code")); return resp; } } catch (Exception e) { e.printStackTrace(); } return resp; } ~~~ * * * ## 本節小結： > 好的，本節關于Android HTTP的第二種請求方式:HttpClient就到這里， 下節開始我們來學習XML以及Json的解析，本節就到這里，謝謝~