HTTPClient4.3的典型小例子

                                                           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       

           

            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();
             }
            }