HttpClient使用

http://blog.csdn.net/z69183787/article/details/48373375
  三个简单的HTTPClient4.3小例子

写三个httpclient的小例子，希望对刚开始学习httpclient的小伙伴们有一个参考↖(^ω^)↗

     1、简单的获取一个HTML页面的内容 

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public void getHTML() throws Exception {                     CloseableHttpClient httpclient = HttpClients.createDefault();                     HttpGet httpget = new HttpGet("http://www.baidu.com/");                     HttpResponse response = httpclient.execute(httpget);                     HttpEntity entity = response.getEntity();                     String html = EntityUtils.toString(entity);                                   httpclient.close();                     }

 

    2、下载一个图片到本地

          

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public class DownloadFile {                  public  static void main(String[] args) throws Exception {                          //图片的网址                        String url = "http://ww2.sinaimg.cn/large/9d57a855jw1dqpv9fp4yuj.jpg";                                                   String destfilename = "D:\\TDDOWNLOAD\\cat.jpg";                            //生成一个httpclient对象                        CloseableHttpClient httpclient = HttpClients.createDefault();                                                          HttpGet httpget = new HttpGet(url);                           HttpResponse response = httpclient.execute(httpget);                        HttpEntity entity = response.getEntity();                        InputStream in = entity.getContent();                        File file = new File(destfilename);                        try {                                FileOutputStream fout = new FileOutputStream(file);                                      int l = -1;                                       byte[] tmp = new byte[1024];                                         while ((l = in.read(tmp)) != -1) {                                      fout.write(tmp,0,l);                                     //注意这里如果用OutputStream.write(buff)的话，图片会失真，大家可以试试                                 }                                      fout.flush();                                     fout.close();                                 } finally {                                     // 关闭低层流。                                     in.close();                                 }                                 httpclient.close();                              }                     }

 

3.post模拟人人网登陆       

           

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import java.io.IOException;             import java.util.ArrayList;             import java.util.List;             import java.util.Scanner;                           import org.apache.http.Header;             import org.apache.http.HttpResponse;             import org.apache.http.NameValuePair;             import org.apache.http.client.ClientProtocolException;             import org.apache.http.client.entity.UrlEncodedFormEntity;             import org.apache.http.client.methods.HttpGet;             import org.apache.http.client.methods.HttpPost;             import org.apache.http.impl.client.CloseableHttpClient;             import org.apache.http.impl.client.HttpClients;             import org.apache.http.message.BasicNameValuePair;             import org.apache.http.util.EntityUtils;                            public class LoginRR {                  private CloseableHttpClient httpclient;                  private HttpPost httppost;//用于提交登陆数据                  private HttpGet httpget;//用于获得登录后的页面                  private String login_success;//用于构造上面的HttpGet                             public  LoginRR()              {                  httpclient = HttpClients.createDefault();                  //人人的登陆界面网址                  httppost = new HttpPost("http://www.renren.com/PLogin.do");              }                             public void logIn(String name, String password) throws Exception              {               //打包将要传入的参数                     List<NameValuePair> params = new ArrayList<NameValuePair>();                     params.add(new BasicNameValuePair("email", name));                     params.add(new BasicNameValuePair("password",password));                     httppost.setEntity(new UrlEncodedFormEntity(params));                                             try {                          //提交登录数据                          HttpResponse re = httpclient.execute(httppost);                          //获得跳转的网址                          Header locationHeader = re.getFirstHeader("Location");                            //登陆不成功                           if (locationHeader == null)                           {                            System.out.println("登陆不成功，请稍后再试!");                            return;                            }                           else//成功                           {                                          login_success=locationHeader.getValue();//获取登陆成功之后跳转链接                                System.out.println("成功之后跳转到的网页网址："+login_success);                                     }                           }catch (ClientProtocolException e) {                      // TODO Auto-generated catch block                      e.printStackTrace();                      } catch (IOException e) {                      // TODO Auto-generated catch block                      e.printStackTrace();                      }             }                             public void PrintText() throws IOException             {                  httpget = new HttpGet(login_success);                  HttpResponse re2 = null;                                     try {                      re2 = httpclient.execute(httpget);                      //输出登录成功后的页面                       String  str=EntityUtils.toString(re2.getEntity());                        System.out.println(str);                       } catch (ClientProtocolException e) {                      // TODO Auto-generated catch block                      e.printStackTrace();                      } catch (IOException e) {                      // TODO Auto-generated catch block                      e.printStackTrace();                      }                      finally                      {                          httppost.abort();                          httpget.abort();                          httpclient.close();                      }              }                             public static void main(String[] args) throws Exception               {                  String name = "username", password = "password ";                      //自己的账号，口令                  LoginRR lr =  new LoginRR();                  lr.logIn(name, password);                  lr.PrintText();                   }             }