Example usage for java.nio.channels FileChannel read

Introduction

In this page you can find the example usage for java.nio.channels FileChannel read.

Prototype

public final long read(ByteBuffer[] dsts) throws IOException 

Source Link

Document

Reads a sequence of bytes from this channel into the given buffers.

Usage

From source file:Main.java

public static void main(String[] args) throws Exception {
    File aFile = new File("C:/test.bin");
    FileInputStream inFile = new FileInputStream(aFile);
    FileChannel inChannel = inFile.getChannel();
    final int PRIMECOUNT = 6;
    ByteBuffer buf = ByteBuffer.allocate(8 * PRIMECOUNT);
    long[] primes = new long[PRIMECOUNT];
    while (inChannel.read(buf) != -1) {
        ((ByteBuffer) (buf.flip())).asLongBuffer().get(primes);
        for (long prime : primes) {
            System.out.printf("%10d", prime);
        }/*from   www.j ava2 s.  c  o m*/
        buf.clear();
    }
    inFile.close();
}

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From source file:ChannelCopy.java

public static void main(String[] args) throws Exception {
    if (args.length != 2) {
        System.out.println("arguments: sourcefile destfile");
        System.exit(1);/*from  w  ww. ja  v  a  2s . co m*/
    }
    FileChannel in = new FileInputStream(args[0]).getChannel(),
            out = new FileOutputStream(args[1]).getChannel();
    ByteBuffer buffer = ByteBuffer.allocate(BSIZE);
    while (in.read(buffer) != -1) {
        buffer.flip(); // Prepare for writing
        out.write(buffer);
        buffer.clear(); // Prepare for reading
    }
}

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From source file:MainClass.java

public static void main(String[] args) {
    File aFile = new File("primes.txt");
    FileInputStream inFile = null;
    try {//from w  w w. j a v  a2 s . co  m
        inFile = new FileInputStream(aFile);
    } catch (FileNotFoundException e) {
        e.printStackTrace(System.err);
    }
    FileChannel inChannel = inFile.getChannel();
    try {
        ByteBuffer lengthBuf = ByteBuffer.allocate(8);
        while (true) {
            if (inChannel.read(lengthBuf) == -1) {
                break;
            }
            lengthBuf.flip();
            int strLength = (int) lengthBuf.getDouble();
            ByteBuffer buf = ByteBuffer.allocate(2 * strLength + 8);
            if (inChannel.read(buf) == -1) {
                break;
            }
            buf.flip();
            byte[] strChars = new byte[2 * strLength];
            buf.get(strChars);
            System.out.println(strLength);
            System.out.println(ByteBuffer.wrap(strChars).asCharBuffer());
            System.out.println(buf.getLong());
            lengthBuf.clear();
        }
        inFile.close();
    } catch (IOException e) {
        e.printStackTrace(System.err);
    }
}

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From source file:MainClass.java

public static void main(String[] args) throws Exception {
    String fromFileName = args[0];
    String toFileName = args[1];/*ww w .j  a v a 2  s .  co  m*/
    FileChannel in = new FileInputStream(fromFileName).getChannel();
    FileChannel out = new FileOutputStream(toFileName).getChannel();

    ByteBuffer buff = ByteBuffer.allocate(32 * 1024);

    while (in.read(buff) > 0) {
        buff.flip();
        out.write(buff);
        buff.clear();
    }

    in.close();
    out.close();
}

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From source file:CopyChannels.java

public static void main(String[] args) throws Exception {
    String fromFileName = "from.txt";
    String toFileName = "to.txt";
    FileChannel in = new FileInputStream(fromFileName).getChannel();
    FileChannel out = new FileOutputStream(toFileName).getChannel();

    ByteBuffer buff = ByteBuffer.allocate(32 * 1024);

    while (in.read(buff) > 0) {
        buff.flip();// w w  w  .  ja  v  a  2 s  . co m
        out.write(buff);
        buff.clear();
    }

    in.close();
    out.close();
}

---

From source file:Main.java

public static void main(String[] args) throws Exception {
    String fromFileName = "from.txt";
    String toFileName = "to.txt";
    FileChannel in = new FileInputStream(fromFileName).getChannel();
    FileChannel out = new FileOutputStream(toFileName).getChannel();

    ByteBuffer buff = ByteBuffer.allocateDirect(32 * 1024);

    while (in.read(buff) > 0) {
        buff.flip();/*from w w w.ja  v  a2s  . c  o m*/
        out.write(buff);
        buff.clear();
    }

    in.close();
    out.close();
}

---

From source file:MainClass.java

public static void main(String[] args) {
    File aFile = new File("file.dat");
    FileInputStream inFile = null;

    try {/*from   ww w  .ja  v a 2s  .co  m*/
        inFile = new FileInputStream(aFile);
    } catch (FileNotFoundException e) {
        e.printStackTrace(System.err);
        System.exit(0);
    }
    FileChannel inChannel = inFile.getChannel();
    final int COUNT = 6;
    ByteBuffer buf = ByteBuffer.allocate(8 * COUNT);
    long[] data = new long[COUNT];
    try {
        while (inChannel.read(buf) != -1) {
            ((ByteBuffer) (buf.flip())).asLongBuffer().get(data);
            System.out.println();
            for (long prime : data)
                System.out.printf("%10d", prime);
            buf.clear();
        }
        System.out.println("\nEOF reached.");
        inFile.close();
    } catch (IOException e) {
        e.printStackTrace(System.err);
        System.exit(1);
    }
}

---

From source file:MainClass.java

public static void main(String[] args) {
    File aFile = new File("C:/test.bin");
    FileInputStream inFile = null;
    try {/*from ww  w.java  2 s .  c  o m*/
        inFile = new FileInputStream(aFile);
    } catch (FileNotFoundException e) {
        e.printStackTrace(System.err);
    }
    FileChannel inChannel = inFile.getChannel();
    final int PRIMECOUNT = 6;
    ByteBuffer buf = ByteBuffer.allocate(8 * PRIMECOUNT);
    long[] primes = new long[PRIMECOUNT];
    try {
        while (inChannel.read(buf) != -1) {
            ((ByteBuffer) (buf.flip())).asLongBuffer().get(primes);
            for (long prime : primes) {
                System.out.printf("%10d", prime);
            }
            buf.clear();
        }
        inFile.close();
    } catch (IOException e) {
        e.printStackTrace(System.err);
    }
}

---

From source file:Main.java

public static void main(String[] args) throws Exception {
    File aFile = new File("primes.txt");
    FileInputStream inFile = new FileInputStream(aFile);
    FileChannel inChannel = inFile.getChannel();
    ByteBuffer buf = ByteBuffer.allocateDirect(1024);
    buf.position(buf.limit());/*from  www .  j  a  v  a 2  s . com*/
    while (true) {
        if (buf.remaining() < 8) {
            if (inChannel.read(buf.compact()) == -1) {
                break;
            }
            buf.flip();
        }
        int strLength = (int) buf.getDouble();
        if (buf.remaining() < 2 * strLength) {
            if (inChannel.read(buf.compact()) == -1) {
                break;
            }
            buf.flip();
        }
        byte[] strChars = new byte[2 * strLength];
        buf.get(strChars);
        if (buf.remaining() < 8) {
            if (inChannel.read(buf.compact()) == -1) {
                break;
            }
            buf.flip();
        }
        System.out.println(strLength);
        System.out.println(ByteBuffer.wrap(strChars).asCharBuffer());
        System.out.println(buf.getLong());
    }
    inFile.close();
}

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From source file:MainClass.java

public static void main(String[] args) throws Exception {
    FileChannel fc = new FileOutputStream("data2.txt").getChannel();
    fc.write(ByteBuffer.wrap("Some text".getBytes()));
    fc.close();/*w  ww.j  av a2  s .c  om*/
    fc = new FileInputStream("data2.txt").getChannel();
    ByteBuffer buff = ByteBuffer.allocate(BSIZE);
    fc.read(buff);
    buff.flip();

    System.out.println(buff.asCharBuffer());
    // Decode using this system's default Charset:
    buff.rewind();
    String encoding = System.getProperty("file.encoding");
    System.out.println("Decoded using " + encoding + ": " + Charset.forName(encoding).decode(buff));
    // Or, we could encode with something that will print:
    fc = new FileOutputStream("data2.txt").getChannel();
    fc.write(ByteBuffer.wrap("Some text".getBytes("UTF-16BE")));
    fc.close();

}

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