通過TCP連接傳輸圖像時遇到問題

Question

我對客戶機服務器映像傳輸有奇怪的行爲。目前，當服務器從緩衝區中讀取32768個字節時總是停頓，總文件大小爲36556字節。 while循環不會結束，但它不會打印其中的任何打印語句，也不會拋出異常。我已經嘗試了幾種不同大小的字節緩衝區，甚至比圖像大小還要大，並不能解決問題。

客戶端代碼：

private static void writePhoto(Socket socket) throws IOException { 

    OutputStream outputStream = new BufferedOutputStream(socket.getOutputStream()); 

    String file_path = "E:\\Eclipse\\Workspace\\DNI_PsuedoClient\\" + 
      "src\\main\\resources\\BuckyBadger.jpg"; 
    try { 
     InputStream stream = new FileInputStream(file_path); 
     System.out.println(stream.available()); 
     try { 
      byte[] buffer = new byte[1024]; 
      int readData; 
      int i = 1; 
      while((readData=stream.read(buffer))!=-1){ 
       System.out.println(readData + " " + i); 
      outputStream.write(buffer,0,readData); 
      i++; 
      } 
      System.out.println("done writing to buffer"); 
     }catch (IOException e) { 
       System.err.println("File Error"); 
       e.printStackTrace(); 
       System.exit(-1); 
     }finally { 
      stream.close(); 
     } 
    } finally { 
    } 
} 

服務器代碼

private static java.io.File createFile(Socket client) throws IOException { 

    System.out.println("Starting to create file"); 
    InputStream stream = new BufferedInputStream(client.getInputStream()); 

    System.out.println("1"); 
    // Create file from the inputStream 
    java.io.File Recieved_File = new java.io.File(thread_ID + ".jpg"); 
    System.out.println(thread_ID + ".jpg"); 
    System.out.println("2"); 

    try { 
     OutputStream outputStream = new FileOutputStream(Recieved_File); 
     System.out.println("3"); 

     try { 
      byte[] buffer = new byte[1024]; 
      System.out.println("4"); 
      int readData; 
      int i = 1; 

      while ((readData = stream.read(buffer)) != -1) { 
       System.out.println("start"); 
       outputStream.write(buffer, 0, readData); 
       System.out.println(readData + " " + i + " " + (i * readData)); 
       i++; 
       System.out.println("end while loop"); 
      } 
     } finally { 
     System.out.println("5"); 
     outputStream.close(); 
     System.out.println("6"); 
     } 
    } finally { 
    } 
    System.out.println("Created file"); 
    return Recieved_File; 
    } 

正如你可以看到我已經使用打印語句中的服務器代碼，試圖找出問題的幾點嘗試。任何見解都會非常有幫助。

爲了進一步的參考，我已經有了完全相同的服務器代碼，用於與Windows手機進行交互，手機在該手機上拍照並將其上傳到服務器。我現在將代碼更改爲在多個線程上運行，並使用模擬交互的Java客戶端首先在Java中進行測試。 Java客戶端正試圖將存儲在驅動器上的照片發送到服務器。客戶端看起來正常工作，因爲它將整張照片放入緩衝區。

我寫了一個協議，那就是：

public DNI_Protocol(Socket socket, String threadID) { 
    client = socket; 
    thread_ID = threadID; 
    } 

public String processInput(String theInput) { 

String theOutput = null; 
if (state == WAITING) { 
    System.out.println(theInput); 
    if (theInput.equals("Upload")) { 
    state = UPLOAD_PHOTO; 
    theOutput = "Send Photo"; 
    } else if (theInput == "View") { 
    state = VIEW; 
    theOutput = "Send Request"; 
    } else { 
    theOutput = "Waiting"; 
    } 
} else if (state == UPLOAD_PHOTO) { 
    // if (theInput != "Sending Photo") { 
    // TODO: Throw a state exception with a message 
    // return "exit"; 
    // } 
    setupDrive(); 
    try { 
    Image_Handle = createFile(client); 
    System.out.println("Uploading file"); 
    uploadedFile = Drive_Interface.uploadFile(false, Image_Handle, drive); 
    System.out.println("file Uploaded"); 
    google_ID = uploadedFile.getId(); 
    System.out.println(google_ID); 
    Image_Handle.delete(); // We are done with the file so we can delete it 
    System.out.println("deleted file"); 
    } catch (IOException e) { 
    e.printStackTrace(); 
    } 
    theOutput = "Send Keywords"; 
    state = UPLOAD_KEYWORDS; 
} else if (state == UPLOAD_KEYWORDS) { 
    if (theInput != "Sending Keywords") { 
    // TODO: Throw a state exception with a message 
    return "exit"; 
    } 
    // TODO: Add code to get keyword arraylist and upload information to 
    // the database 
    theOutput = "exit"; 
} 
return theOutput; 

}

Answer 1

 int sum = 0; 
     while ((readData = stream.read(buffer)) != -1, && sum < 36556) { 
     System.out.println("start"); 
     outputStream.write(buffer, 0, readData); 
     System.out.println(readData + " " + i + " " + (i * readData)); 
     i++; 
     sum = sum + readData; 
     System.out.println("end while loop"); 
    } 

該代碼在32768字節的完全相同的位置停頓;

Answer 2

你的服務器代碼這樣說：

 while ((readData = stream.read(buffer)) != -1) { 
      System.out.println("start"); 
      outputStream.write(buffer, 0, readData); 
      System.out.println(readData + " " + i + " " + (i * readData)); 
      i++; 
      System.out.println("end while loop"); 
     } 

這使得從套接字讀取直到套接字關閉或服務器出現錯誤，沒有其他原因read將返回-1。由於這些條件都不會發生，服務器將停留在此循環中。你根本沒有寫任何代碼來處理文件的末尾。

如果服務器知道它將讀取特定數量的字節，則它在讀取該字節數時需要跳出while循環。如果客戶端要通過關閉套接字或關閉TCP連接的一個方向告訴服務器它已完成發送文件，則客戶端需要代碼來完成此操作。否則，服務器將永遠等待。