54 lines
1.4 KiB
Java
54 lines
1.4 KiB
Java
// newio/GetChannel.java
|
|
// (c)2020 MindView LLC: see Copyright.txt
|
|
// We make no guarantees that this code is fit for any purpose.
|
|
// Visit http://OnJava8.com for more book information.
|
|
// Getting channels from streams
|
|
import java.nio.*;
|
|
import java.nio.channels.*;
|
|
import java.io.*;
|
|
|
|
public class GetChannel {
|
|
private static String name = "data.txt";
|
|
private static final int BSIZE = 1024;
|
|
public static void main(String[] args) {
|
|
// Write a file:
|
|
try(
|
|
FileChannel fc = new FileOutputStream(name)
|
|
.getChannel()
|
|
) {
|
|
fc.write(ByteBuffer
|
|
.wrap("Some text ".getBytes()));
|
|
} catch(IOException e) {
|
|
throw new RuntimeException(e);
|
|
}
|
|
// Add to the end of the file:
|
|
try(
|
|
FileChannel fc = new RandomAccessFile(
|
|
name, "rw").getChannel()
|
|
) {
|
|
fc.position(fc.size()); // Move to the end
|
|
fc.write(ByteBuffer
|
|
.wrap("Some more".getBytes()));
|
|
} catch(IOException e) {
|
|
throw new RuntimeException(e);
|
|
}
|
|
// Read the file:
|
|
try(
|
|
FileChannel fc = new FileInputStream(name)
|
|
.getChannel()
|
|
) {
|
|
ByteBuffer buff = ByteBuffer.allocate(BSIZE);
|
|
fc.read(buff);
|
|
buff.flip();
|
|
while(buff.hasRemaining())
|
|
System.out.write(buff.get());
|
|
} catch(IOException e) {
|
|
throw new RuntimeException(e);
|
|
}
|
|
System.out.flush();
|
|
}
|
|
}
|
|
/* Output:
|
|
Some text Some more
|
|
*/
|