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7.1.4 Android HTTP请求方式:HttpClient | 小熊教程

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本节引言:

在上一节中我们对HttpURLConnection进行了学习,本节到第二种方式:HttpClient,尽管被Google 弃用了,但是我们我们平时也可以拿HttpClient来抓下包,配合Jsoup解析网页效果更佳!HttpClient 用于接收/发送Http请求/响应,但不缓存服务器响应,不执行HTML页面潜入的JS代码,不会对页面内容 进行任何解析,处理!开始本节内容!


1.HttpClient使用流程

基本流程


2.HttpClient使用示例

1)使用HttpClient发送GET请求

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直接贴下简单的发送Get请求的代码:

 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();     }  } 

运行截图

另外,如果是带有参数的GET请求的话,我们可以将参数放到一个List集合中,再对参数进行URL编码, 最后和URL拼接下就好了:

 List<BasicNameValuePair> params = new LinkedList<BasicNameValuePair>();   params.add(new BasicNameValuePair("user", "猪小弟"));   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发送POST请求

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POST请求比GET稍微复杂一点,创建完HttpPost对象后,通过NameValuePair集合来存储等待提交 的参数,并将参数传递到UrlEncodedFormEntity中,最后调用setEntity(entity)完成, HttpClient.execute(HttpPost)即可;这里就不写例子了,暂时没找到Post的网站,又不想 自己写个Servlet,So,直接贴核心代码吧~

核心代码:

 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", "猪大哥"));                 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抓数据示例(教务系统数据抓取)

其实关于HttpClient的例子有很多,比如笔者曾经用它来抓学校教务系统上学生的课程表: 这就涉及到Cookie,模拟登陆的东西,说到抓数据(爬虫),一般我们是搭配着JSoup来解析 抓到数据的,有兴趣可以自己查阅相关资料,这里贴下笔者毕设app里获取网页部分的关键 代码!大家可以体会下:

HttpClient可以通过下述代码获取与设置Cookie: HttpResponse loginResponse = new DefaultHttpClient().execute(getLogin); 获得Cookie:cookie = loginResponse.getFirstHeader(“Set-Cookie”).getValue(); 请求时带上Cookie:httpPost.setHeader(“Cookie”, cookie);

 //获得链接,模拟登录的实现: public int getConnect(String user, String key) throws Exception {     // 先发送get请求 获取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);         // 获取响应的cookie值         cookie = loginResponse.getFirstHeader("Set-Cookie").getValue();         System.out.println("cookie= " + cookie);     }      // 第二步:模拟登录     // 发送Post请求,禁止重定向     HttpPost httpPost = new HttpPost(true_url);     httpPost.getParams().setParameter(ClientPNames.HANDLE_REDIRECTS, false);      // 设置Post提交的头信息的参数     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);      // 设置请求数据     List<NameValuePair> params = new ArrayList<NameValuePair>();      params.add(new BasicNameValuePair("__VIEWSTATE",             getViewState(loginhtml)));// __VIEWSTATE参数,如果变化可以动态抓取获取     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,竟然不需要验证码      // 设置编码方式,响应请求,获取响应状态码:     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);      // 重定向状态码为302     if (Status == 302 || Status == 301) {         // 获取头部信息中Location的值         location = response.getFirstHeader("Location").getValue();         System.out.println(location);         // 第三步:获取管理信息的主页面         // Get请求         HttpGet httpGet = new HttpGet(ip_url + location);// 带上location地址访问         httpGet.setHeader("Referer", true_url);         httpGet.setHeader("Cookie", cookie);          // 主页的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发送Put请求

示例代码如下

 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; } 

本节小结:

好的,本节关于Android HTTP的第二种请求方式:HttpClient就到这里, 下节开始我们来学习XML以及Json的解析,本节就到这里,谢谢~

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