Examples of FileChannel

java.nio.channels.FileChannel
An abstract channel type for interaction with a platform file.
A FileChannel defines the methods for reading, writing, memory mapping, and manipulating the logical state of a platform file. This type does not have a method for opening files, since this behaviour has been delegated to the FileInputStream, FileOutputStream, and RandomAccessFile types.

FileChannels created from a FileInputStream, or a RandomAccessFile created in mode "r", are read-only. FileChannels created from a FileOutputStream are write-only. FileChannels created from a RandomAccessFile created in mode "rw" are read/write. FileChannels created from a RandomAccessFile that was opened in append-mode will also be in append-mode -- meaning that each write will be preceeded by a seek to the end of file. Some platforms will seek and write atomically, others will not.

FileChannels has a virtual pointer into the file which is refered to as a file position. The position can be manipulated by repositioning it within the file, and its current position can be queried.

FileChannels also have an associated size. The size of the file is the number of bytes that it currently contains. The size can be manipulated by adding more bytes to the end of the file (which increases the size) or truncating the file (which decreases the size). The current size can also be queried.

FileChannels have operations beyond the simple read, write, and close. They can also:
- request that cached data be forced onto the disk
- lock ranges of bytes associated with the file
- transfer data directly to another channel in a manner that has the potential to be optimized by the platform
- memory-mapping files into NIO buffers to provide efficient manipulation of file data
- read and write to the file at absolute byte offsets in a fashion that does not modify the current position
FileChannels are thread-safe. Only one operation involving manipulation of the file position may be in-flight at once. Subsequent calls to such operations will block, and one of those blocked will be freed to continue when the first operation has completed. There is no ordered queue or fairness applied to the blocked threads.

It is undefined whether operations that do not manipulate the file position will also block when there are any other operations in-flight.

The logical view of the underlying file is consistent across all FileChannels and IO streams opened on the same file by the same JVM process. Therefore modifications performed via a channel will be visible to the stream, and vice versa; including modifications to the file position, content, size, etc.
org.apache.flume.channel.file.FileChannel

A durable {@link Channel} implementation that uses the local file system forits storage.

FileChannel works by writing all transactions to a set of directories specified in the configuration. Additionally, when a commit occurs the transaction is synced to disk.

FileChannel is marked {@link org.apache.flume.annotations.InterfaceAudience.Private} because itshould only be instantiated via a configuration. For example, users should certainly use FileChannel but not by instantiating FileChannel objects. Meaning the label Private applies to user-developers not user-operators. In cases where a Channel is required by instantiated by user-developers {@link org.apache.flume.channel.MemoryChannel} should be used.

Examples of java.nio.channels.FileChannel

    return true;
  }
  
  public static void writeBytesToFile(byte[] bytes, String destination) {
    try {
      FileChannel fc = new FileOutputStream(destination).getChannel();
      fc.write(ByteBuffer.wrap(bytes));
      fc.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }

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Examples of java.nio.channels.FileChannel

   * @exception XException if any error occurs
   */
  protected void copyFile(String sourceFile, String targetFile)
      throws XException
  {
    FileChannel srcChannel = null;
    FileOutputStream fos = null;
    FileChannel dstChannel = null;


    try
    {
      // Get a file channel for the SourceFile
      File lockSourceFile = new File(sourceFile);
      srcChannel = new RandomAccessFile(lockSourceFile, "r")
          .getChannel();


      // Create channel on the destination
      fos = new FileOutputStream(targetFile);
      dstChannel = fos.getChannel();


      // Copy file contents from source to destination
      dstChannel.transferFrom(srcChannel, 0, srcChannel.size());


    }
    catch (IOException e)
    {
      throw new XException(Constants.LOCATION_EXTERN,
          Constants.LAYER_TECHNICAL,
          Constants.PACKAGE_TECHNICAL_FILE, "0", e);
    }
    finally
    {
      try
      {
        if (srcChannel != null)
        {
          srcChannel.close();
        }
        if (fos != null)
        {
          fos.close();
        }
        if (dstChannel != null)
        {
          dstChannel.close();
        }
      }
      catch (IOException e)
      {
        throw new XException(Constants.LOCATION_EXTERN,

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Examples of java.nio.channels.FileChannel

        FutureResponseHandler respHdl = new FutureResponseHandler();
        BodyDataSink dataSink = con.send(new HttpRequestHeader("POST", "http://localhost:" + server.getLocalPort() + "/"), respHdl);
        
        
        RandomAccessFile raf = new RandomAccessFile(file, "r");
        FileChannel fc = raf.getChannel();
        dataSink.transferFrom(fc);
        fc.close();
        raf.close();
        dataSink.close();
        
        IHttpResponse response = respHdl.getResponse();

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Examples of java.nio.channels.FileChannel

        FutureResponseHandler respHdl = new FutureResponseHandler();
        BodyDataSink dataSink = con.send(new HttpRequestHeader("POST", "http://localhost:" + server.getLocalPort() + "/"), respHdl);
        
        
        RandomAccessFile raf = new RandomAccessFile(file, "r");
        FileChannel fc = raf.getChannel();
        dataSink.transferFrom(fc);
        fc.close();
        raf.close();
        dataSink.close();
        
        IHttpResponse response = respHdl.getResponse();

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Examples of java.nio.channels.FileChannel

 */
public class SrcIndexDat {


  public static  Map<Int128, Index> loadFile(String fileName) throws Throwable {
    Map<Int128, Index> result = new Hashtable<Int128, Index>();
    FileChannel channel = new RandomAccessFile(fileName,"rw").getChannel();
    
    channel.position(4+4);
    
    ByteBuffer data;
    
    data = getByteBuffer(4);
    
    channel.read(data);
    int count = data.getInt(0);
    
    for(int i=0;i<count;i++) {
      data = getByteBuffer(16);
      channel.read(data);
      Int128 key_id = new Int128(data.array());
      data = getByteBuffer(4);
      channel.read(data);
      Index index = new Index(key_id);
      int source_count = data.getInt(0);
    
      for(int j = 0;j<source_count;j++) {
        data = getByteBuffer(16);
        channel.read(data);
        ClientID client_id = new ClientID(data.array());


        data = getByteBuffer(8);
        channel.read(data);
        long creation_time = data.getLong(0);
        data = getByteBuffer(1);
        channel.read(data);
        int tagCount = data.get(0);
        TagList tagList = new TagList();
        
        for(int k = 0;k<tagCount;k++) {
          Tag tag = TagScanner.scanTag(channel);

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Examples of java.nio.channels.FileChannel

    
    return result;
  }
  
  public static void writeFile(String fileName, Map<Int128, Index> sourceData) throws Throwable {
    FileChannel channel = new FileOutputStream(fileName).getChannel();
    ByteBuffer data = getByteBuffer(4);
    
    data.put(SRC_INDEX_VERSION);
    data.position(0);
    channel.write(data);
    
    data.position(0);
    data.putInt(Convert.longToInt(System.currentTimeMillis()));
    data.position(0);
    channel.write(data);
    
    data.position(0);
    data.putInt(sourceData.size());
    data.position(0);
    channel.write(data);
    
    for(Int128 key : sourceData.keySet()) {
      data = getByteBuffer(16);
      data.put(key.toByteArray());
      data.position(0);
      channel.write(data);
      
      Index index = sourceData.get(key);
      data = getByteBuffer(4);
      data.putInt(index.getSourceList().size());
      data.position(0);
      channel.write(data);
      
      for(Source source : index.getSourceList()) {
        data = getByteBuffer(16);
        data.put(source.getClientID().toByteArray());
        data.position(0);
        channel.write(data);
        
        data = getByteBuffer(8);
        data.putLong(0, source.getCreationTime());
        data.position(0);
        channel.write(data);
        
        data = getByteBuffer(1);
        data.put(Convert.intToByte(source.getTagList().size()));
        data.position(0);
        channel.write(data);
        for(Tag tag : source.getTagList()) {
          ByteBuffer buffer = tag.getAsByteBuffer();
          buffer.position(0);
          channel.write(buffer);
        }
      }
    }
  }

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Examples of java.nio.channels.FileChannel

   */
  public static List<KadContact> loadFile(String fileName) {
    List<KadContact> result = new LinkedList<KadContact>();
    
    try {
      FileChannel channel = new RandomAccessFile(fileName,"rw").getChannel();
      
      ByteBuffer data = getByteBuffer(4);
      channel.position(4); // skip 'old' contacts count field
      
      channel.read(data); // nodes.dat version
      
      data.position(0);
      channel.read(data);
      
      int totalContacts = data.getInt(0);
      
      for(int i = 1 ; i <= totalContacts ; i++) {
        
        data = getByteBuffer(16);
        channel.read(data);
        ClientID contact_id = new ClientID(data.array());
        data = getByteBuffer(4);
        channel.read(data);
        byte[] ip = data.array().clone();
        //ip = Convert.reverseArray(ip);
        IPAddress address = new IPAddress(ip);
        
        data = getByteBuffer(2);
        channel.read(data);
        short udp_port = data.getShort(0);
        
        data = getByteBuffer(2);
        channel.read(data);
        short tcp_port = data.getShort(0);
        
        data = getByteBuffer(1);
        channel.read(data);
        byte contact_version = data.get(0); 
        
        data = getByteBuffer(4);
        channel.read(data);
        
        ByteBuffer data2 = getByteBuffer(4);
        channel.read(data2);
        
        JKadUDPKey udp_key = new JKadUDPKey(data.array(), data2.array());
        
        data = getByteBuffer(1);
        channel.read(data);


        if (Utils.isGoodAddress(address)) {
          KadContact contact = new KadContact(contact_id, new ContactAddress(address, Convert.shortToInt(udp_port)), Convert.shortToInt(tcp_port), contact_version, udp_key, data.get(0)==1 ? true : false);
          
          result.add(contact);
        }
      }
      
      channel.close();
    }catch(Throwable t) {
      t.printStackTrace();
    }
    
    return result;

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Examples of java.nio.channels.FileChannel

        current_hashing_file = null;
        if (stop)
          return;
        try {
          current_hashing_file = shared_completed_file;
          FileChannel file_channel = new FileInputStream(
              shared_completed_file.getFile()).getChannel();
          file_hashing = new FileHashing(file_channel);
          file_hashing.start();
          file_hashing.join();
          file_channel.close();
          files_needed_to_hash.remove(shared_completed_file);
          if (!file_hashing.isDone())
            continue;
          if (sharedFiles.containsKey(file_hashing.getFileHashSet()
              .getFileHash()))

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Examples of java.nio.channels.FileChannel

   * @param fileName
   * @param contactList
   */
  public static void writeFile(String fileName, List<KadContact> contactList) {
    try {
      FileChannel channel = new FileOutputStream(fileName).getChannel();
      ByteBuffer data = getByteBuffer(4);
      
      channel.write(data);
      
      data.position(0);
      data.put(NODES_DAT_VERSION);
      data.position(0);
      channel.write(data);
      
      data.position(0);
      data.putInt(contactList.size());
      data.position(0);
      channel.write(data);
      
      for(KadContact contact : contactList) {
        data = getByteBuffer(16);
        data.put(contact.getContactID().toByteArray());
        data.position(0);
        channel.write(data);
        
        data = getByteBuffer(4);
        data.put(contact.getIPAddress().getAddress());
        data.position(0);
        channel.write(data);
        
        data  = getByteBuffer(2);
        data.putShort(intToShort(contact.getUDPPort()));
        data.position(0);
        channel.write(data);
        
        data  = getByteBuffer(2);
        data.putShort(intToShort(contact.getTCPPort()));
        data.position(0);
        channel.write(data);
        
        data  = getByteBuffer(1);
        data.put(contact.getVersion());
        data.position(0);
        channel.write(data);
        
        // write key
        JKadUDPKey key = contact.getKadUDPKey();
        if (key == null) {
          data  = getByteBuffer(4 + 4);
          data.position(0);
          channel.write(data);
        } else {
          data  = getByteBuffer(4 + 4);
          data.put(key.getKey());
          data.put(key.getAddress().getAddress());
          data.position(0);
          channel.write(data);
        }
        
        data = getByteBuffer(1);
        data.put((byte)(contact.isIPVerified() ? 1 : 0));
        data.position(0);
        channel.write(data);
      }
      
      channel.close();
    } catch (Throwable t) {
      t.printStackTrace();
    }
  }

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Examples of java.nio.channels.FileChannel

    }
    notifyPropertyChanged(JKAD_ID_KEY, newID);
  }
  
  private void storeUserHash() throws Throwable {
    FileChannel output_channel = new FileOutputStream(USER_HASH_FILE).getChannel();
    ByteBuffer hash = Misc.getByteBuffer(16);
    hash.put(user_hash.getUserHash());
    hash.position(0);
    output_channel.write(hash);
    output_channel.close();
  }

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