当生活像一首歌那样轻快流畅时，笑颜常开乃易事；而在一切事都不妙时仍能微笑的人，是真正的乐观。——威尔科克斯
曾经我们使用java的IO流复制文件时是这么写的
package com.ruben; import java.io.*; import java.util.Optional; /** * @ClassName: FileDemo * @Description: 我还没有写描述 * @Date: 2021/1/10 0010 21:38 * * * @author: <achao1441470436@gmail.com> * @version: 1.0 * @since: JDK 1.8 */ public class FileDemo { private static final String FILE_PATH = "D:/file/files/ps/2077.png"; private static final String TARGET_PATH = "D:/file/files/ps/1977.png"; public static void main(String[] args) { InputStream dataInputStream = null; OutputStream output = null; try { dataInputStream = new FileInputStream(FILE_PATH); output = new FileOutputStream(TARGET_PATH); byte[] buffer = new byte[1024]; int length; while ((length = dataInputStream.read(buffer)) > 0) { output.write(buffer, 0, length); } } catch (IOException e) { e.printStackTrace(); } finally { Optional.ofNullable(output).ifPresent(outputStream -> { try { outputStream.close(); } catch (IOException e) { e.printStackTrace(); } }); Optional.ofNullable(dataInputStream).ifPresent(inputStream -> { try { inputStream.close(); } catch (IOException e) { e.printStackTrace(); } }); } } }
可以看到在finally里我们关闭流的时候要写一大堆，非常麻烦
现在推荐使用这种写法
package com.ruben; import java.io.*; import java.util.Optional; /** * @ClassName: FileDemo * @Description: 我还没有写描述 * @Date: 2021/1/10 0010 21:38 * * * @author: <achao1441470436@gmail.com> * @version: 1.0 * @since: JDK 1.8 */ public class FileDemo { private static final String FILE_PATH = "D:/file/files/ps/2077.png"; private static final String TARGET_PATH = "D:/file/files/ps/1977.png"; public static void main(String[] args) { try ( InputStream dataInputStream = new FileInputStream(FILE_PATH); OutputStream output = new FileOutputStream(TARGET_PATH) ) { byte[] buffer = new byte[1024]; int length; while ((length = dataInputStream.read(buffer)) > 0) { output.write(buffer, 0, length); } } catch (IOException e) { e.printStackTrace(); } } }
使用try()catch{}写法，可以自动关闭流
