用SeekableByteChannel读取文件
import java.io.*; import java.nio.*; import java.nio.file.*;//来自 n o w j a v a . c o m import java.nio.channels.*; public class FindInt { private Path file; FindInt(Path file) { this.file = file; } public int seek() throws IOException { int num = -1; try (SeekableByteChannel fc = Files.newByteChannel(file)) { ByteBuffer buf = ByteBuffer.allocate(8); //Get the offset into the file. fc.read(buf); /* from NowJava.com - 时 代 Java */ long offset = buf.getLong(0); //Seek to the offset location. fc.position(offset); buf.rewind(); //Read the 'secret' value. fc.read(buf); num = buf.getInt(0); } catch (IOException x) { System.err.println(x); } return num; } public static void main(String[] args) throws IOException { Path file = Paths.get("datafile"); int num = new FindInt(file).seek(); System.out.println("The value is " + num); } }