import org.apache.http.HttpEntity;
import org.apache.http.HttpHost;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.entity.ContentType;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.protocol.ExecutionContext;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.EntityUtils;

public class HttpClientDemo {

 /**
  * 獲取重定向之后的網址信息
  * @see HttpClient缺省會自動處理客戶端重定向
  * @see 即訪問網頁A后,假設被重定向到了B網頁,那么HttpClient將自動返回B網頁的內容
  * @see 若想取得B網頁的地址,就需要借助HttpContext對象,HttpContext實際上是客戶端用來在多次請求響應的交互中,保持狀態信息的
  * @see 我們自己也可以利用HttpContext來存放一些我們需要的信息,以便下次請求的時候能夠取出這些信息來使用
  */
 public static void getRedirectInfo(){
  HttpClient httpClient = new DefaultHttpClient();
  HttpContext httpContext = new BasicHttpContext();
  HttpGet httpGet = new HttpGet("http://127.0.0.1:8088/blog/main.jsp");
  try {
   //將HttpContext對象作為參數傳給execute()方法,則HttpClient會把請求響應交互過程中的狀態信息存儲在HttpContext中
   HttpResponse response = httpClient.execute(httpGet, httpContext);
   //獲取重定向之后的主機地址信息,即"http://127.0.0.1:8088"
   HttpHost targetHost = (HttpHost)httpContext.getAttribute(ExecutionContext.HTTP_TARGET_HOST);
   //獲取實際的請求對象的URI,即重定向之后的"/blog/admin/login.jsp"
   HttpUriRequest realRequest = (HttpUriRequest)httpContext.getAttribute(ExecutionContext.HTTP_REQUEST);
   System.out.println("主機地址:" + targetHost);
   System.out.println("URI信息:" + realRequest.getURI());
   HttpEntity entity = response.getEntity();
   if(null != entity){
    System.out.println("響應內容:" + EntityUtils.toString(entity, ContentType.getOrDefault(entity).getCharset()));
    EntityUtils.consume(entity);
   }
  } catch (Exception e) {
   e.printStackTrace();
  }finally{
   httpClient.getConnectionManager().shutdown();
  }
 }
}