Java读取文件夹大小的6种方法及代码
(一)单线程递归方式
package com.taobao.test;
import java.io.File;
public class TotalFileSizeSequential {
public static String fileName = "C:\\Documents and Settings\\Administrator\\桌面\\monkeytalk";
// 递归方式 计算文件的大小
private long getTotalSizeOfFilesInDir(final File file) {
if (file.isFile())
return file.length();
final File[] children = file.listFiles();
long total = 0;
if (children != null)
for (final File child : children)
total += getTotalSizeOfFilesInDir(child);
return total;
}
public static void main(final String[] args) {
final long start = System.nanoTime();
final long total = new TotalFileSizeSequential()
.getTotalSizeOfFilesInDir(new File(fileName));
final long end = System.nanoTime();
System.out.println("Total Size: " + total);
System.out.println("Time taken: " + (end - start) / 1.0e9);
}
}
(二)使用Executors.newFixedThreadPool和callable 多线程实现
package com.taobao.test;
import java.io.File;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
public class ConcurrentTotalFileSize {
public static final String fileName = "C:\\Documents and Settings\\Administrator\\桌面\\monkeytalk";
class SubDirectoriesAndSize {
final public long size;
final public List<File> subDirectories;
public SubDirectoriesAndSize(final long totalSize,
final List<File> theSubDirs) {
size = totalSize;
subDirectories = Collections.unmodifiableList(theSubDirs);
}
}
private SubDirectoriesAndSize getTotalAndSubDirs(final File file) {
long total = 0;
final List<File> subDirectories = new ArrayList<File>();
if (file.isDirectory()) {
final File[] children = file.listFiles();
if (children != null)
for (final File child : children) {
if (child.isFile())
total += child.length();
else
subDirectories.add(child);
}
}
return new SubDirectoriesAndSize(total, subDirectories);
}
private long getTotalSizeOfFilesInDir(final File file)
throws InterruptedException, ExecutionException, TimeoutException {
final ExecutorService service = Executors.newFixedThreadPool(100);
try {
long total = 0;
final List<File> directories = new ArrayList<File>();
directories.add(file);
while (!directories.isEmpty()) {
final List<Future<SubDirectoriesAndSize>> partialResults = new ArrayList<Future<SubDirectoriesAndSize>>();
for (final File directory : directories) {
partialResults.add(service
.submit(new Callable<SubDirectoriesAndSize>() {
public SubDirectoriesAndSize call() {
return getTotalAndSubDirs(directory);
}
}));
}
directories.clear();
for (final Future<SubDirectoriesAndSize> partialResultFuture : partialResults) {
final SubDirectoriesAndSize subDirectoriesAndSize = partialResultFuture
.get(100, TimeUnit.SECONDS);
directories.addAll(subDirectoriesAndSize.subDirectories);
total += subDirectoriesAndSize.size;}}return total;}finally{
service.shutdown();}}
public static void main(finalString[] args)throws InterruptedException,ExecutionException,TimeoutException{finallong start =System.nanoTime();finallong total = newConcurrentTotalFileSize().getTotalSizeOfFilesInDir(newFile(fileName));finallongend=System.nanoTime();System.out.println("Total Size: "+ total);System.out.println("Time taken: "+(end- start)/1.0e9);}}
(三)使用Executors.newFixedThreadPool和callable 多线程的另外一种实现
package com.taobao.test;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
public class NaivelyConcurrentTotalFileSize {
public static String fileName = "C:\\Documents and Settings\\Administrator\\桌面\\monkeytalk";
private long getTotalSizeOfFilesInDir(final ExecutorService service,
final File file) throws InterruptedException, ExecutionException,
TimeoutException {
if (file.isFile())
return file.length();
long total = 0;
final File[] children = file.listFiles();
if (children != null) {
final List<Future<Long>> partialTotalFutures = new ArrayList<Future<Long>>();
for (final File child : children) {
partialTotalFutures.add(service.submit(new Callable<Long>() {
public Long call() throws InterruptedException,
ExecutionException, TimeoutException {
return getTotalSizeOfFilesInDir(service, child);
}
}));
}
for (final Future<Long> partialTotalFuture : partialTotalFutures)
total += partialTotalFuture.get(100, TimeUnit.SECONDS);
}
return total;
}
private long getTotalSizeOfFile(final String fileName)
throws InterruptedException, ExecutionException, TimeoutException {
final ExecutorService service = Executors.newFixedThreadPool(100);
try {
return getTotalSizeOfFilesInDir(service, new File(fileName));
} finally {
service.shutdown();
}
}
public static void main(final String[] args) throws InterruptedException,
ExecutionException, TimeoutException {
final long start = System.nanoTime();
final long total = new NaivelyConcurrentTotalFileSize()
.getTotalSizeOfFile(fileName);
final long end = System.nanoTime();
System.out.println("Total Size: " + total);
System.out.println("Time taken: " + (end - start) / 1.0e9);
}
}
(四)使用CountDownLatch和AtomicLong实现多线程下的并发控制
package com.taobao.test;
import java.io.File;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
public class ConcurrentTotalFileSizeWLatch {
private ExecutorService service;
final private AtomicLong pendingFileVisits = new AtomicLong();
final private AtomicLong totalSize = new AtomicLong();
final private CountDownLatch latch = new CountDownLatch(1);
public static String fileName = "C:\\Documents and Settings\\Administrator\\桌面\\monkeytalk";
private void updateTotalSizeOfFilesInDir(final File file) {
long fileSize = 0;
if (file.isFile())
fileSize = file.length();
else {
final File[] children = file.listFiles();
if (children != null) {
for (final File child : children) {
if (child.isFile())
fileSize += child.length();
else {
pendingFileVisits.incrementAndGet();
service.execute(new Runnable() {
public void run() {
updateTotalSizeOfFilesInDir(child);
}
});
}
}
}
}
totalSize.addAndGet(fileSize);
if (pendingFileVisits.decrementAndGet() == 0)
latch.countDown();
}
private long getTotalSizeOfFile(final String fileName)
throws InterruptedException {
service = Executors.newFixedThreadPool(100);
pendingFileVisits.incrementAndGet();
try {
updateTotalSizeOfFilesInDir(new File(fileName));
latch.await(100, TimeUnit.SECONDS);
return totalSize.longValue();
} finally {
service.shutdown();
}
}
public static void main(final String[] args) throws InterruptedException {
final long start = System.nanoTime();
final long total = new ConcurrentTotalFileSizeWLatch()
.getTotalSizeOfFile(fileName);
final long end = System.nanoTime();
System.out.println("Total Size: " + total);
System.out.println("Time taken: " + (end - start) / 1.0e9);
}
}
(五)使用BlockingQueue和AtomicLong的实现
package com.taobao.test;
import java.io.File;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
public class ConcurrentTotalFileSizeWQueue {
public static String fileName = "C:\\Documents and Settings\\Administrator\\桌面\\monkeytalk";
private ExecutorService service;
final private BlockingQueue<Long> fileSizes = new ArrayBlockingQueue<Long>(
500);
final AtomicLong pendingFileVisits = new AtomicLong();
private void startExploreDir(final File file) {
pendingFileVisits.incrementAndGet();
service.execute(new Runnable() {
public void run() {
exploreDir(file);
}
});
}
private void exploreDir(final File file) {
long fileSize = 0;
if (file.isFile())
fileSize = file.length();
else {
final File[] children = file.listFiles();
if (children != null)
for (final File child : children) {
if (child.isFile())
fileSize += child.length();
else {
startExploreDir(child);
}
}
}
try {
fileSizes.put(fileSize);
} catch (Exception ex) {
throw new RuntimeException(ex);
}
pendingFileVisits.decrementAndGet();
}
private long getTotalSizeOfFile(final String fileName)
throws InterruptedException {
service = Executors.newFixedThreadPool(100);
try {
startExploreDir(new File(fileName));
long totalSize = 0;
while (pendingFileVisits.get() > 0 || fileSizes.size() > 0) {
final Long size = fileSizes.poll(10, TimeUnit.SECONDS);
totalSize += size;
}
return totalSize;
} finally {
service.shutdown();
}
}
public static void main(final String[] args) throws InterruptedException {
final long start = System.nanoTime();
final long total = new ConcurrentTotalFileSizeWQueue()
.getTotalSizeOfFile(fileName);
final long end = System.nanoTime();
System.out.println("Total Size: " + total);
System.out.println("Time taken: " +(end- start)/1.0e9);}}
(六)使用jdk7的ForkJoin来实现
package com.taobao.test;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.ForkJoinTask;
import java.util.concurrent.RecursiveTask;
public class FileSize {
private final static ForkJoinPool forkJoinPool = new ForkJoinPool();
public static String fileName = "C:\\Documents and Settings\\Administrator\\桌面\\monkeytalk";
private static class FileSizeFinder extends RecursiveTask<Long> {
final File file;
public FileSizeFinder(final File theFile) {
file = theFile;
}
@Override
public Long compute() {
long size = 0;
if (file.isFile()) {
size = file.length();
} else {
final File[] children = file.listFiles();
if (children != null) {
List<ForkJoinTask<Long>> tasks = new ArrayList<ForkJoinTask<Long>>();
for (final File child : children) {
if (child.isFile()) {
size += child.length();
} else {
tasks.add(new FileSizeFinder(child));
}
}
for (final ForkJoinTask<Long> task : invokeAll(tasks)) {
size += task.join();
}
}
}
return size;
}
}
public static void main(final String[] args) {
final long start = System.nanoTime();
final long total = forkJoinPool.invoke(new FileSizeFinder(new File("/home")));
final long end = System.nanoTime();
System.out.println("Total Size: " + total);
System.out.println("Time taken: " + (end - start) / 1.0e9);
}
}
Java读取文件夹大小的6种方法及代码的更多相关文章
- JAVA读取文件夹大小的几种方式
(一)单线程递归方式 package com.taobao.test; import java.io.File; public class TotalFileSizeSequential { publ ...
- JAVA读取文件夹大小
几种不同的实现方法: (一)单线程递归方式 package com.taobao.test; import java.io.File; public class TotalFileSizeSequen ...
- C#读取文件夹大小
今天需要做一个读取文件夹大小的功能,为了避免遍历文件夹下所有文件并求出总大小,找到如下的好方法: 首先要在项目中引用一个COM组件:Microsoft Scripting Runtime,这个在Ref ...
- Mac 中显示资源库（Library）文件夹目录的几种方法
Mac中Library目录在10.6.7系统之后默认隐藏的,要想找到此文件夹有如下几种方法: 1. 用命令可以使其显示: 在终端中执行命令: chflags nohidden ~/Library ...
- java读取文件夹下所有文件并替换文件每一行中指定的字符串
import java.io.BufferedReader; import java.io.File; import java.io.FileInputStream; import java.io.I ...
- java读取文件夹下文件及txt内容
public class PositionController { // 读取txt内容 public static String txt2String(File file) { ...
- 使用java读取文件夹中文件的行数
使用java统计某文件夹下所有文件的行数 经理突然交代一个任务:要求统计某个文件夹下所有文件的行数.在网上查了一个多小时没有解决.后来心里不爽就决定自己写一个java类用来统计文件的行数,于是花了两个 ...
- VC++实现获取文件占用空间大小的两种方法(非文件大小)
// GetFileSpaceSize.cpp : Defines the entry point for the console application. // /***************** ...
- PHP 获取远程文件的大小的3种方法
1.使用file_get_contents() <?php $file = file_get_contents($url); echo strlen($file); ?> 2. 使用get ...
随机推荐
- uCGUI字符串显示过程分析和uCGUI字库的组建
为什么要分析字符串的显示过程? 学习uCGUI主要是学习如何使用的,为何要深究到源码的层次呢? 就分析字符串显示过程的原因来说,是因为移植汉字字库的需要.uCGUI并么有合适的汉字字库,而且完整的汉字 ...
- GCC交叉编译链命名
命名格式: arch[-vendor][-os]-abi arch:CPU的架构 vendor:工具链的供应商 os: 目标上运行的操作系统,不同的操作系统对应着不同的C库,例如 newlib.gli ...
- Xcode常见错误以及解决方案
一．Undefined symbols for architecture x86_64: Xcode升级到5.1 新特性之一就是默认让所有App都通过64位编译器编译.原来在Xcode5.0.x的时候 ...
- iOS新上线注意事项
上传不出现构建版本 现在苹果要求先上传版本,然后在提交审核,但是现在经常上传完应用后,不出现构建版本,等待很久很久,也不出现,那么怎么解决,我告诉你~~尼玛的苹果是自己数据丢包了,结果就造成你不出现构 ...
- Ubuntu添加PPA源
转自Ubuntu添加PPA源 什么是PPA PPA,表示Personal Package Archives,也就是个人软件包集 很多软件包由于各种原因吧,不能进入官方的Ubuntu软件仓库.为了方便U ...
- 【HDOJ】1097 A hard puzzle
题目和1061非常相似,几乎可以复用. #include <stdio.h> ][]; int main() { int a, b; int i, j; ; i<; ++i) { b ...
- 转载：CEO应向软件工程师学习的7个技能
软件工程师的哪些技能是值得CEO学习的?显然,软件工程师是逻辑的,高效的,注重细节的,有计划的,并且大多数CEO也是如此.但是,软件工程师还有一些更微妙,甚至是令人懊恼的品质,那么CEO是否可以从中学 ...
- 为什么你的 phpinfo() 无法显示
一.问题描述 编写了一个php文件test.php,代码如下: <?php echo phpinfo(); ?> 浏览器访问了一下,却返回了 NULL. 二.问题定位及解决 网上查了下,大 ...
- a++与=++a的区别
//a++;//a=a+1; // ++a;//a=a+1; //Console.WriteLine(a++);// Console.WriteL ...
- uiview scale
http://stackoverflow.com/questions/3946797/cgaffinetransformmakescale-makes-uiview-jump-to-original- ...