文件拷贝
这个题目在笔试的时候经常出现，下面的代码给出了两种实现方案
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import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.nio.ByteBuffer;import java.nio.channels.FileChannel;public final class MyUtil { private MyUtil() { throw new AssertionError(); } public static void fileCopy(String source, String target) throws IOException { try (InputStream in = new FileInputStream(source)) { try (OutputStream out = new FileOutputStream(target)) { byte[] buffer = new byte[4096]; int bytesToRead; while((bytesToRead = in.read(buffer)) != -1) { out.write(buffer, 0, bytesToRead); } } } } public static void fileCopyNIO(String source, String target) throws IOException { try (FileInputStream in = new FileInputStream(source)) { try (FileOutputStream out = new FileOutputStream(target)) { FileChannel inChannel = in.getChannel(); FileChannel outChannel = out.getChannel(); ByteBuffer buffer = ByteBuffer.allocate(4096); while(inChannel.read(buffer) != -1) { buffer.flip(); outChannel.write(buffer); buffer.clear(); } } } }} |
注意：上面用到Java 7的TWR，使用TWR后可以不用在finally中释放外部资源 ，从而让代码更加优雅。
