java/src/main/com/google/appengine/api/files/FileWriteChannelImpl.java

   1 // Copyright 2011 Google Inc. All Rights Reserved.
   2
   3 package com.google.appengine.api.files;
   4
   5 import java.io.IOException;
   6 import java.nio.ByteBuffer;
   7 import java.nio.channels.ClosedChannelException;
   8
   9 /**
  10  * An implementation of {@code FileWriteChannel}.
  11  *
  12  */
  13 class FileWriteChannelImpl implements FileWriteChannel {
  14
  15   private FileServiceImpl fileService;
  16   private AppEngineFile file;
  17   private boolean lockHeld;
  18   private boolean isOpen;
  19
  20   FileWriteChannelImpl(AppEngineFile f, boolean lock, FileServiceImpl fs) {
  21     this.file = f;
  22     this.lockHeld = lock;
  23     this.fileService = fs;
  24     isOpen = true;
  25     if (null == file) {
  26       throw new NullPointerException("file is null");
  27     }
  28     if (!f.isWritable()) {
  29       throw new IllegalArgumentException("file is not writable");
  30     }
  31   }
  32
  33   private void checkOpen() throws ClosedChannelException {
  34     if (!isOpen) {
  35       throw new ClosedChannelException();
  36     }
  37   }
  38
  39   /**
  40    * {@inheritDoc}
  41    */
  42   public int write(ByteBuffer src) throws IOException {
  43     return write(src, null);
  44   }
  45
  46   /**
  47    * {@inheritDoc}
  48    */
  49   public int write(ByteBuffer buffer, String sequenceKey) throws IOException {
  50     checkOpen();
  51     return fileService.append(file, buffer, sequenceKey);
  52   }
  53
  54   /**
  55    * {@inheritDoc}
  56    */
  57   public boolean isOpen() {
  58     return isOpen;
  59   }
  60
  61   /**
  62    * {@inheritDoc}
  63    */
  64   public void close() throws IOException {
  65     if (!isOpen) {
  66       return;
  67     }
  68     fileService.close(file, false);
  69     isOpen = false;
  70   }
  71
  72   /**
  73    * {@inheritDoc}
  74    */
  75   public void closeFinally() throws IllegalStateException, IOException {
  76     if (!lockHeld) {
  77       throw new IllegalStateException("The lock for this file is not held by the current request");
  78     }
  79     if (isOpen) {
  80       fileService.close(file, true);
  81     } else {
  82       try {
  83         fileService.openForAppend(file, true);
  84         fileService.close(file, true);
  85       } catch (FinalizationException e) {
  86       }
  87     }
  88     isOpen = false;
  89   }
  90
  91 }