Android之Http沟通——4.Android HTTP索取信息:HttpClient

it2025-07-20 8

本节介绍:

他谈到了部分HttpURLConnection。本节HttpClient该，Apache为我们提供HttpClient(简单的Http客户端),只是毕竟不是亲儿子。HttpClient在API 21版本号后就给Google弃用了。而我们实际开发中。非常多页面都不是通过一个简单的URL就能够訪问的，可能须要登陆或者相关权限才干够訪问，这就涉及到了Session,Cookie等的问题了；当然我们能够用HttpURLConnection来实现，可是有点麻烦。而用HttpClient能够简单点。HttpClient用于接收/发送Http请求/响应。但不缓存server响应，不执行HTML页面潜入的JS代码，不会对页面内容进行不论什么解析。处理；要改掉废话太多的习惯，SO简化博文，開始本节内容吧：

HttpClient使用流程:

基本流程:

HttpClient使用演示样例:

1.发送GET请求

嗯，就写个简单的发送GET请求的代码吧:

package com.example.httpclientdemo; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.util.EntityUtils; import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.View; import android.view.View.OnClickListener; import android.webkit.WebView; import android.widget.Button; 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(); } }

另外。假设是带有參数的GET请求的话，我们能够把參数放到List集合中，在对參数进行URL编码: 然后和URL拼接

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);

接着贴下执行截图:

2.发送POST请求

POST请求比GET略微复杂一点。创建完HttpPost对象后，通过NameValuePair集合来存储等待提交的參数。并将參数传递到UrlEncodedFormEntity中，最后调用setEntity(entity)完毕， HttpClient.execute(HttpPost)就可以。这里就不写样例了。临时没找到Post的站点，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.胡说八道

事实上关于HttpClient的样例有非常多。比方笔者以前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，有兴趣能够自己查阅相关文档。至于笔者的毕设，代码非常烂的说。兴许有时间整理在公布出来吧。这里贴下模拟登陆教务系统部分的代码。大家能够体会下HttpClient：

//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:基本的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提交的头信息的參数 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參数，假设变化能够动态抓取获取 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,居然不须要验证码 // 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地址訪问 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; }

总结:

好的，本节关于HttpClient就到这里吧，内容还是比較简单的~ 下节我们将使用retrofit来封装我们的HTTP请求。敬请期待~ 对了，关于Android里简单的网络技术能够參考小猪之前写过的入门系列: 小猪的Android入门之路 day 8 part 3

转载于:https://www.cnblogs.com/bhlsheji/p/4842675.html

相关资源：数据结构—成绩单生成器

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