HTTPClient4.3的典型小例子

                                                           三個簡單的HTTPClient4.3小例子

寫三個httpclient的小例子，但願對剛開始學習httpclient的小夥伴們有一個參考↖(^ω^)↗

     一、簡單的獲取一個HTML頁面的內容 

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();
                    }

    二、下載一個圖片到本地

          

      public class DownloadFile {
                 public  static void main(String[] args) throws Exception {
                         //圖片的網址
                       String url = "http://ww2.sinaimg.cn/large/9d57a855jw1dqpv9fp4yuj.jpg";
                         
                       String destfilename = "D:\\TDDOWNLOAD\\cat.jpg";
                           //生成一個httpclient對象
                       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);
                                    //注意這裏若是用OutputStream.write(buff)的話，圖片會失真，你們能夠試試
                                } 
                                    fout.flush();
                                    fout.close();
                                } finally {
                                    // 關閉低層流。
                                    in.close();
                                }
                                httpclient.close();
                             }
                    }

3.post模擬人人網登錄       

           

            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;//用於提交登錄數據
                 private HttpGet httpget;//用於得到登陸後的頁面
                 private String login_success;//用於構造上面的HttpGet
             
             public  LoginRR()
             {
                 httpclient = HttpClients.createDefault();
                 //人人的登錄界面網址
                 httppost = new HttpPost("http://www.renren.com/PLogin.do");
             }
             
             public void logIn(String name, String password) throws Exception
             { 
             //打包將要傳入的參數
                    List<NameValuePair> params = new ArrayList<NameValuePair>();
                    params.add(new BasicNameValuePair("email", name));
                    params.add(new BasicNameValuePair("password",password));
                    httppost.setEntity(new UrlEncodedFormEntity(params));  
                    
                    try {
                         //提交登陸數據
                         HttpResponse re = httpclient.execute(httppost);
                         //得到跳轉的網址
                         Header locationHeader = re.getFirstHeader("Location");  
                         //登錄不成功
                          if (locationHeader == null)
                          {
                           System.out.println("登錄不成功，請稍後再試!");
                           return; 
                          }
                          else//成功
                          {          
                               login_success=locationHeader.getValue();//獲取登錄成功以後跳轉連接
                               System.out.println("成功以後跳轉到的網頁網址："+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);
                     //輸出登陸成功後的頁面 
                     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 ";
                     //本身的帳號，口令
                 LoginRR lr =  new LoginRR();
                 lr.logIn(name, password);
                 lr.PrintText();     
             }
            }