今天分享SeekabnlerByteChannel API，，通常搭配Files中的ByteChannel，主要功能是可以用position方法指定開始讀取的位置，再指定要讀多少byte，簡單範例如下

/*
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 * and open the template in the editor.
 */
package mysee;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.SeekableByteChannel;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

/**
 *
 * @author joombuopre
 */
public class Mysee {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws IOException {
       // TODO code application logic here
        Path dw=Paths.get("L:\\Tian.txt");
        //01818G773s7Gmmm3mss967s3848s423GSM253smms18gS97159645220s636m75S0s6S85702670mmSggmm78s2482277s8s98M
        int bufferSize =8;
        
        try(SeekableByteChannel sb= Files.newByteChannel(dw)){
            ByteBuffer buffer= ByteBuffer.allocate(bufferSize);
            sb.position(4); // set pointer to 4
            sb.read(buffer); // begin read after 4
            for(int i=0;i<8;i++){
                System.out.print((char)buffer.get(i)); //8G773s7G
            }
            
            System.out.println();
            buffer.clear();
            sb.position(0); //point set back to 0
            sb.read(buffer); //read start at 0
            for(int i=0;i<4;i++){
                System.out.print((char)buffer.get(i)); // 0181
            }
            System.out.println();
        }
    }
}