下面哪些可以做到文件的复制? A. import org.apache.commons.io.FileUtils; File source = new File("ajava.txt"); File target = new File("ajava-backup.txt"); FileUtils.copyFile(source, target); B. import java.nio.file.Files; File source = new File("ajava.txt"); File target = new File("ajava-backup.txt"); Files.copy(source.toPath(), target.toPath()); C. import java.nio.channels.FileChannel; FileChannel input = new FileInputStream("givenfile").getChannel(); FileChannel output = new FileOutputStream("tofile").getChannel(); output.transferFrom(input, 0, input.size()); D. FileInputStream input = new FileInputStream(new File("文件路径")); FileOutputStream output = new FileOutputStream(new File("目标文件路径")); byte[] bt = new byte[1024]; int realbyte = 0; while ((realbyte = input.read(bt)) > 0) { output.write(bt,0,realbyte); }