錯誤：讀取輸入後無法寫入輸出

Question

我想從java桌面應用程序登錄到網站，但主要問題是textbox的ID隨每個請求而變化。

<input type="text" maxlength="10" name="UserName_88515" id="UserName_88515" />

這裏的ID仍然相同，直到_，每個請求下一個5個位數的變化。所以我決定先閱讀網頁並檢索5位數字。然後我試圖寫入數據登錄到網站。但是我收到上面提到的錯誤。請幫忙。

public class LoginHandler { 

static boolean isLoggedIn = false; 
static String toastText, myText; 

public void login(String usrname, String password, String cookys, String sessionCode) { 

     try { 

      URL url = new URL("http://www.somewebsite.com/home.php?session=" 
        + sessionCode); 
      HttpURLConnection conn = (HttpURLConnection) url.openConnection(); 
      conn.setDoOutput(true); 
      conn.setRequestMethod("GET"); 
      conn.setRequestProperty("User-Agent", 
        "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20100101 Firefox/17.0"); 
      conn.setRequestProperty("Cookie", cookys); 
      conn.setDoOutput(true); 

      final BufferedReader rd = new BufferedReader(new InputStreamReader(conn.getInputStream())); 

      final StringBuilder response = new StringBuilder(); 
      myText = response.toString(); 
      String line; 

      while ((line = rd.readLine()) != null) { 
       response.append(line); 
      } 
      rd.close(); 

      final String text1 = response.toString(); 
      final int starIndex = text1.indexOf("UserName_"); 
      final int endIndex = starIndex + 15; 
      System.err.println("This is starIndex" + starIndex); 
      System.err.println("This is endIndex" + endIndex); 
      final String avc = text1.substring(starIndex, endIndex); 
      System.err.println("This is avc\n" + avc); 
      final String fin = avc.substring(10, 15); 
      System.err.println("This is fin\n" + fin); 

      final String data1 = URLEncoder.encode("MessageLength", "UTF-8") 
        + "=" + URLEncoder.encode("140", "UTF-8") + "&" 
        + URLEncoder.encode("UserName_" + fin, "UTF-8") + "=" 
        + URLEncoder.encode("username", "UTF-8") + "&" 
        + URLEncoder.encode("Password_" + fin, "UTF-8") + "=" 
        + URLEncoder.encode("password", "UTF-8") + "&" 
        + URLEncoder.encode("LoginNowbtnDiv", "UTF-8") + "=" 
        + URLEncoder.encode("Login Now", "UTF-8") + "&" 
        + URLEncoder.encode("LoginNow", "UTF-8") + "=" 
        + URLEncoder.encode("Login Now", "UTF-8"); 

      System.err.println("THIS IS Data1:\n " + data1); 

      final OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream()); 
      wr.write(data1); 
      wr.flush(); 

      final BufferedReader rd1 = new BufferedReader(new InputStreamReader(conn.getInputStream())); 

      final StringBuilder response1 = new StringBuilder(); 
      String line1; 

      while ((line1 = rd1.readLine()) != null) { 
       response1.append(line1); 
      } 

      final String text2 = response1.toString(); 
      System.err.println("This is second response\n" + text2); 
      rd1.close(); 
     } catch (Exception ex) { 
      ex.printStackTrace(); 
     } 
    } 
} 

編輯

SEVERE: java.net.ProtocolException: Cannot write output after reading input. 
at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1083) 
at mypack.UltooSender.send(UltooSender.java:80) 
at mypack.NewServlet.processRequest(NewServlet.java:41) 
at mypack.NewServlet.doGet(NewServlet.java:63) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:668) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:770) 
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1542) 
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281) 
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175) 
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655) 
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595) 
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161) 
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331) 
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231) 
at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317) 
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195) 
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:849) 
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:746) 
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1045) 
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:228) 
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137) 
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104) 
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90) 
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79) 
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54) 
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59) 
at com.sun.grizzly.ContextTask.run(ContextTask.java:71) 
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532) 
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513) 
at java.lang.Thread.run(Thread.java:722) 

SEVERE:  at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1083) 
SEVERE:  at mypack.UltooSender.send(UltooSender.java:80) 
SEVERE:  at mypack.NewServlet.processRequest(NewServlet.java:41) 
SEVERE:  at mypack.NewServlet.doGet(NewServlet.java:63) 
SEVERE:  at javax.servlet.http.HttpServlet.service(HttpServlet.java:668) 
SEVERE:  at javax.servlet.http.HttpServlet.service(HttpServlet.java:770) 
SEVERE:  at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1542) 
SEVERE:  at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281) 
SEVERE:  at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175) 
SEVERE:  at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655) 
SEVERE:  at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595) 
SEVERE:  at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161) 
SEVERE:  at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331) 
SEVERE:  at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231) 
SEVERE:  at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317) 
SEVERE:  at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195) 
SEVERE:  at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:849) 
SEVERE:  at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:746) 
SEVERE:  at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1045) 
SEVERE:  at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:228) 
SEVERE:  at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137) 
SEVERE:  at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104) 
SEVERE:  at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90) 
SEVERE:  at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79) 
SEVERE:  at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54) 
SEVERE:  at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59) 
SEVERE:  at com.sun.grizzly.ContextTask.run(ContextTask.java:71) 
SEVERE:  at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532) 
SEVERE:  at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513) 
SEVERE:  at java.lang.Thread.run(Thread.java:722) 

Answer 1

如果你獲得HttpURLConnection.getInputStream後試圖讓HttpURLConnection.getOutputStream（）會出現此異常（）。

在這一行你得到的InputStream，

final BufferedReader rd = new BufferedReader(new InputStreamReader(conn.getInputStream())); 

在這一行你想獲得的OutputStream，

final OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());