Java HttpURLConnection 头

Question

我正在尝试从服务器列表中获取 apache 版本。我正在考虑解析 header ，但是我无法发送 HEAD 但它可以与 GET POST 等一起使用。

这是我的代码:

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.Scanner;
import javax.*;

public class SiteCycler {

public static void main(String args[]) throws IOException  {

    Vars vars = new Vars();
    SendEmail sendemail = new SendEmail();

    FileInputStream fis = new FileInputStream("D:/WRKSPC/Sender/src/sites.txt");
    Scanner scanner = new Scanner(fis);

    System.out.println("Reading file line by line in Java using Scanner");
    int i = 0;
    File outFile = new File ("C:/output.txt");
    FileWriter fWriter = new FileWriter (outFile);
    PrintWriter pWriter = new PrintWriter (fWriter);
    while(scanner.hasNextLine()){

        //System.out.println(scanner.nextLine());

        String str = scanner.nextLine();
        Vars.site = str;
        System.out.println(Vars.site);
        URL url;
        HttpURLConnection connection = null;  
        try {
          //Create connection
             String urlParameters =
                        "server=" + URLEncoder.encode("???", "UTF-8");

          url = new URL("http://www."+str+"/server-status/");
          connection = (HttpURLConnection)url.openConnection();
          // connection.setDoOutput(true);
          connection.setRequestMethod("HEAD");
          connection.setRequestProperty("Content-Type", 
               "application/x-www-form-urlencoded");



          connection.setRequestProperty("Content-Length", "" + 
                   Integer.toString(urlParameters.getBytes().length));
          connection.setRequestProperty("Content-Language", "en-US");  

          connection.setUseCaches (false);
          connection.setDoInput(true);
          connection.setDoOutput(true);

          //Send request
          DataOutputStream wr = new DataOutputStream (
                      connection.getOutputStream ());
          wr.writeBytes (urlParameters);
          wr.flush ();
          wr.close ();

          //Get Response    
          InputStream is = (InputStream) connection.getInputStream();
          BufferedReader rd = new BufferedReader(new InputStreamReader(is));
          String line;
          StringBuffer response = new StringBuffer(); 
          while((line = rd.readLine()) != null) {
            response.append(line);
            response.append('\r');
            System.out.println(line);
          }
          rd.close();


        } catch (Exception e) {

          e.printStackTrace();


        } finally {

          if(connection != null) {
            connection.disconnect(); 
          }
        }
       // if(true){ //this will be the check
             pWriter.println (str);
            // SendEmail.main(args);

       // }else{

       // }


       // new String("SiteID"+i);

    }

    pWriter.close();

    scanner.close();
}   
}

这方面的结果

    java.net.ProtocolException: HTTP method HEAD doesn't support output
at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(Unknown Source)
at SiteCycler.main(SiteCycler.java:70)

Answer 1

您可能需要删除 connection.setDoOutput(true); 行。HttpUrlConnection 对象上的意外参数会产生错误。

HEAD 请求不提供OutputStream。