7.1.4 Android HTTP请求方式:HttpClient

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 ent