HttpClient使用

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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 

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

          

      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 params = new ArrayList(); 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(); } }

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