將消息從Java應用程序發送到servlet並顯示它

我的目標是從Java應用程序（JA）向servlet（S）發送簡單消息並將其顯示在瀏覽器頁面上。我希望每次運行servlet類（刷新瀏覽器頁面）時，都會收到消息。將消息從Java應用程序發送到servlet並顯示它

我使用BufferedWriter在S上傳輸JA和BufferedReader上的輸出以接收它，但我想我做錯了什麼。

下面是從JA的代碼片段：

try{ 
     URL url = new URL("http://(/*ip address*/:8080/FirstServlet/myfirstservlet");     
     URLConnection conn = url.openConnection();     
     conn.setDoOutput(true); 
     conn.setDoInput(true);     
     BufferedWriter out = new BufferedWriter(new OutputStreamWriter(conn.getOutputStream())); 
     out.write("testing");    
     out.flush(); 
     out.close();   
     BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));    
     String response; 
     while((response = in.readLine()) != null) { 
      //System.out.println(response); 
     } 
     in.close(); 
     } 
     catch (MalformedURLException ex) { 
      ex.printStackTrace(); 
     } 
     catch (IOException iex) { 
      iex.printStackTrace(); 
     }

下面是從S碼：

import javax.servlet.*; 
import javax.servlet.http.*; 
import java.io.*; 
import java.util.*; 

public class FirstServlet extends HttpServlet { 
    private final static String _USERNAME = "username"; 

    public void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException , IOException { 

     PrintWriter out = res.getWriter(); 


     BufferedReader bufferedReader = null; 
     StringBuilder stringBuilder = new StringBuilder(); 
     char test = 'a'; 
     try{ 
      InputStream inputStream = req.getInputStream(); 

      if (inputStream != null) { 
       bufferedReader = new BufferedReader(new InputStreamReader(inputStream)); 

       char[] charBuffer = new char[128]; 
       int bytesRead = -1; 

       while ((bytesRead = bufferedReader.read(charBuffer)) > 0) { 
        stringBuilder.append(charBuffer, 0, bytesRead); 
        out.println(charBuffer); //expecting this to be displayed on browser 
       } 
      } else { 
       stringBuilder.append(""); 
       out.println("0"); 
      } 
     } catch (IOException ex) { 
      ex.printStackTrace(); 
     } 

    }

我試圖在同時包裝我的JA的代碼（在自己的線程中運行）（真）循環，但似乎沒有幫助。任何幫助，將不勝感激。謝謝！

來源

2016-08-02 KS7X

我相信你需要使用' HttpURLConnection'而不是'URLConnection'，並且調用'setRequestMethod（「GET」）'來啓動正確的HTTP通信，所以servlet容器知道調用哪個servlet的方法。 –

@Jozef：不，OP只是在尋找推動力，但基本概念錯了。 KS7X，你的servlet基本上是迴應Java應用程序（在'response'變量中），而不是你所期望的「瀏覽器頁面」。哪些對解決您的問題最有幫助？ http://stackoverflow.com/q/25947790或http://stackoverflow.com/q/32426674？ – BalusC

感謝@BalusC，這兩個鏈接都給我一個新的途徑，讓我的申請工作。 – KS7X

-1

有兩個誤區：

首先，servlet的返回結果字符串不是在瀏覽器中，但在你的應用程序JA。
通過使用conn.getOutputStream（），您隱式設置請求方法類型爲「POST」值，因此您必須在servlet中實現「doPost」方法來處理請求。

JA - 發送請求和servlet的返回響應字符串：

try { 

URL url = new URL("http://(/*ip address*/:8080/FirstServlet/myfirstservlet"); 
HttpURLConnection conn = (HttpURLConnection) url.openConnection(); 
conn.setRequestMethod("POST"); 
conn.setDoOutput(true); 
conn.setDoInput(true); 


conn.setRequestProperty("Content-Type", "text/html"); 
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(conn.getOutputStream())); 
out.write("testing"); 
out.flush(); 
out.close(); 

BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream())); 

String responsePart; 
StringBuilder resultString = new StringBuilder(); 

while ((responsePart = in.readLine()) != null) { 
    resultString.append(responsePart); 
} 
in.close(); 

System.out.println("Response from servlet: " + resultString); 

} catch (MalformedURLException ex) { 
    ex.printStackTrace(); 
} catch (IOException iex) { 
    iex.printStackTrace(); 
}

的S - 這是由JA送回JA返回的字符串：

protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { 

    dummy(); 
    PrintWriter out = res.getWriter(); 
    BufferedReader bufferedReader = null; 
    StringBuilder stringBuilder = new StringBuilder(); 
    char test = 'a'; 

    res.setContentType("text/html"); 
    try{ 
     InputStream inputStream = req.getInputStream(); 

     if (inputStream != null) { 
      bufferedReader = new BufferedReader(new InputStreamReader(inputStream)); 

      char[] charBuffer = new char[128]; 
      int bytesRead = -1; 

      while ((bytesRead = bufferedReader.read(charBuffer)) > 0) { 
       stringBuilder.append(charBuffer, 0, bytesRead); 

      } 

      //Return string to JA 
      out.println(stringBuilder.toString()); 

     } else { 
      stringBuilder.append(""); 
      out.println("0"); 
     } 
    } catch (IOException ex) { 
     ex.printStackTrace(); 
    } 
}

來源

2016-08-02 22:17:29 Azat

將消息從Java應用程序發送到servlet並顯示它

回答

相關問題