Java随机流实现断点续传

import java.io.RandomAccessFile;

/**
 * 用随机流实现断点续传
 */
public class RandomAccessFile3 {

	public static void main(String[] args) {
		// 声明随机输入流与输出流
		RandomAccessFile r = null;
		RandomAccessFile w = null;
		try {
			// 创建随机输入流与输出流对象
			r = new RandomAccessFile("D:\\视频1.zip", "rw");
			w = new RandomAccessFile("a\\a.zip", "rw");

			long a = w.length();// 记录文件读写位置
			System.out.println(a);
			// 读取文件内容
			byte[] b = new byte[500];
			int len = r.read(b);
			while (len != -1) {
				w.write(b, 0, len);
				len = r.read(b);
			}
			System.out.println("文件复制成功");
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if (r != null) {
					r.close();
				}
				if (w != null) {
					r.close();
				}
			} catch (Exception e2) {
				e2.printStackTrace();
			}
		}
	}
}