通过fileChannel复制文件

  

 

传统的文件复制都是利用 缓冲输入输出流来完成

 

最近在网上发现了一个更加高效简单的方法:利用FileChannel.

 

先再写次传统的方法:

 

public void bufferedFileCopy(File src, File dest) {
		InputStream fis = null;
		OutputStream fos = null;

		try {
			fis = new BufferedInputStream(new FileInputStream(src));
			fos = new BufferedOutputStream(new FileOutputStream(dest));

			byte[] buffer = new byte[2048];
			int len;

			while ((len = fis.read(buffer)) != -1) {
				fos.write(buffer, 0, len);
			}

		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			try {
				fis.close();
				fos.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}

		}

	}

 

利用FileChannel的高效简单方法:

 

public void channelFileCopy(File src, File dest) {

		FileInputStream fis = null;
		FileOutputStream fos = null;

		FileChannel in = null;
		FileChannel out = null;

		try {
			fis = new FileInputStream(src);

			fos = new FileOutputStream(dest);

			in = fis.getChannel();

			out = fos.getChannel();

			in.transferTo(0, in.size(), out);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			try {
				fis.close();
				in.close();
				fos.close();
				out.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}

		}

	}

只需一句关键就完成文件复制功能:

in.transferTo(0, in.size(), out);

再来看看耗时情况:

				File src = new File(mFileHelper.SDCardPath() + "/1.zip");
				File dest = new File(mFileHelper.SDCardPath()
						+ "/kingzhengTourGuide/videos/1.zip");

				/**
				 * 先看看传统方法耗时
				 */
				long start = System.currentTimeMillis();

				mFileHelper.bufferedFileCopy(src, dest);

				long end = System.currentTimeMillis();

				System.out.println("利用buffered复制,用时: " + (end - start) + "ms");

 

				/**
				 * 再看看FileChannel耗时
				 */

				start = System.currentTimeMillis();

				mFileHelper.channelFileCopy(src, dest);

				end = System.currentTimeMillis();

				System.out.println("利用FileChannel复制,用时: " + (end - start)
						+ "ms");

 

 

 

有点奇怪 竟然耗时还多了...在测试其他文件的时候 使用FileChannel 会少将近 三分之一;

 

有兴趣的同学可以自己试试~~