sviolet.thistle.util.file.FastFileCopyer Maven / Gradle / Ivy
/*
* Copyright (C) 2015-2017 S.Violet
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Project GitHub: https://github.com/shepherdviolet/thistle
* Email: [email protected]
*/
package sviolet.thistle.util.file;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;
/**
* 文件复制器快速版
*
* @author S.Violet
*/
public class FastFileCopyer {
/**
*
* 单线程最快的复制文件方法
* 目标文件的修改时间与原文件保持基本一致
* 目标文件修改时间可能会偏大,偏差<2000ms, 例如:
* 原始文件修改时间:****2356
* 目标文件修改时间:****4000
*
*
* @param source 源文件
* @param target 目标文件
*/
public static void copy(File source,File target) throws IOException {
try (FileInputStream inStream = new FileInputStream(source); FileOutputStream outStream = new FileOutputStream(target)) {
try (FileChannel in = inStream.getChannel(); FileChannel out = outStream.getChannel()){
long totalSize = in.size();
long readSize = 0;
while(totalSize > 0 && readSize < totalSize){
readSize += in.transferTo(readSize, totalSize - readSize, out);
}
}
outStream.flush();
}
//使目标文件修改时间与源文件保持一致
long lastModified = source.lastModified();
//解决有时候取出负数, 无法设置时间的问题
if(lastModified < 0L) {
lastModified = 0L;
}
target.setLastModified(lastModified);
}
}