Java ClosedChannelException用法及代码示例

// Java Program to Illustrate Working of
// ClosedChannelException
// Importing required classes
// Input output classes
import java.io.IOException;
import java.io.RandomAccessFile;
// Classes from java.nio package
import java.nio.ByteBuffer;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.FileChannel;
import java.nio.charset.Charset;
// Main class
// For ClosedChannelException
public class GFG {
    // Main driver method
    public static void main(String args[])
        throws IOException
    {
        // Try block to check for exceptions
        try {
            // Open a file in your system using the
            // RandomAccessFile class Custom local directory
            // on machine
            RandomAccessFile randomAccessFile
                = new RandomAccessFile(
                    "D:/Documents/textDoc.txt", "rw");
            // Now creating a channel using the FileChannel
            // class to the file opened using the
            // RandomAccessFile class
            FileChannel fileChannel
                = randomAccessFile.getChannel();
            // Create a buffer to read bytes from the
            // channel using the ByteBuffer class
            ByteBuffer byteBuffer
                = ByteBuffer.allocate(512);
            Charset charset = Charset.forName("US-ASCII");
            // Close the file channel
            // We do this so the exception is thrown
            fileChannel.close();
            // Try to read from the fileChannel which is now
            // closed
            while (fileChannel.read(byteBuffer) > 0) {
                byteBuffer.rewind();
                System.out.print(
                    charset.decode(byteBuffer));
                byteBuffer.flip();
            }
            // Closing the connections to free up memory
            // resources using close() method
            randomAccessFile.close();
        }
        // Catch block to handle the exceptions
        // Handling Application specific Exception
        catch (ClosedChannelException e) {
            // Print message if exception is occurred
            System.out.println(
                "ClosedChannelException has occurred");
        }
    }
}