控制台程序，在Junk目录中将字符串“Garbage in, garbage out\n”写入到名为charData.txt的文件中。
import static java.nio.file.StandardOpenOption.*;
import java.nio.file.*;
import java.nio.channels.*; import java.util.EnumSet;
import java.io.IOException;
import java.nio.ByteBuffer; public class BufferStateTrace {
public static void main(String[] args) {
String phrase = "Garbage in, garbage out.\n"; Path file = Paths.get(System.getProperty("user.home")).resolve("Beginning Java Struff").resolve("charData.txt"); // Path object for the file
try {
Files.createDirectories(file.getParent()); // Make sure we have the directory
} catch (IOException e) {
e.printStackTrace();
System.exit(1);
} try (WritableByteChannel channel = Files.newByteChannel(file, EnumSet.of(WRITE, CREATE, APPEND))) {
ByteBuffer buf = ByteBuffer.allocate(1024);
System.out.printf(
"\nNew buffer: position = %1$2d Limit = %2$4d capacity = %3$4d",
buf.position(), buf.limit(), buf.capacity());
// Load the data into the buffer
for(char ch : phrase.toCharArray())
buf.putChar(ch);
System.out.printf(
"\nBuffer after loading: position = %1$2d Limit = %2$4d capacity = %3$4d",
buf.position(), buf.limit(), buf.capacity());
buf.flip(); // Flip the buffer ready for file write
System.out.printf(
"\nBuffer after flip: position = %1$2d Limit = %2$4d capacity = %3$4d",
buf.position(), buf.limit(), buf.capacity());
channel.write(buf); // Write the buffer to the file channel // Uncomment the following to get the size of the file in the output
// System.out.println("\nThe file contains " + ((FileChannel)channel).size() + " bytes."); buf.flip();
channel.write(buf); // Write the buffer again to the file channel
System.out.println("\nBuffer contents written to the file.");
} catch (IOException e) {
e.printStackTrace();
}
}
}