java随机读取文件

package randomRead;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
//随机读取文件
public class RandomTest {

	public static void main(String[] args) {
		RandomTest t = new RandomTest();
		
		File src = new File("d:\\holen.xml");
		File dest = new File("d:\\copy.txt");
		t.copy(src, dest, 0, 8);
	}

	public void copy(File src, File dest, int start, int end) {
		try {
			RandomAccessFile in = new RandomAccessFile(src, "r");  //读取文件
			RandomAccessFile out = new RandomAccessFile(dest, "rw");  //写文件

			int buf_size = 1024;
			byte[] buf = new byte[buf_size];
			int out_end = (int) out.length(); // 追加到文件结尾

			while (start < end) {
				int len = end - start;
				if (len > buf_size) {
					len = buf_size;
				}

				in.seek(start);  //指向源文件的开始位置
				in.read(buf, 0, len);  //把文件内容读入缓冲区
				
				out.seek(out_end); //指向目标文件的结束位置

				out.write(buf, 0, len); //把文件内容写入缓冲区
				
				start += len;
				out_end += len;
			}

			in.close();
			out.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}

	}

}