幾種不一樣的實現方法:java
package com.taobao.test; import java.io.File; public class TotalFileSizeSequential { public static String fileName = "C:\\Documents and Settings\\Administrator\\桌面\\monkeytalk"; // 遞歸方式 計算文件的大小 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); } }
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(final String[] args) throws InterruptedException, ExecutionException, TimeoutException { final long start = System.nanoTime(); final long total = new ConcurrentTotalFileSize() .getTotalSizeOfFilesInDir(new File(fileName)); final long end = System.nanoTime(); System.out.println("Total Size: " + total); System.out.println("Time taken: " + (end - start) / 1.0e9); } }
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); } }
package com.sunsheen.jfids.studio.monitor.utils.local; import java.io.File; import java.math.BigDecimal; import java.math.RoundingMode; 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; /** * 獲得指定文件夾大小(使用CountDownLatch和AtomicLong實現多線程下的併發控制) * @author WangSong * */ public class FileUtil { private ExecutorService service; final private AtomicLong pendingFileVisits = new AtomicLong(); final private AtomicLong totalSize = new AtomicLong(); final private CountDownLatch latch = new CountDownLatch(1); // private String fileName; // public FileUtil(String fileName){ // this.fileName = fileName; // } //更新文件總大小(多線程) private void updateTotalSizeOfFilesInDir(final File file) { long fileSize = 0;//初始化文件大小 //文件,直接返回大小 if (file.isFile()) fileSize = file.length(); //文件夾,遍歷全部文件總大小 else { final File[] children = file.listFiles(); if(null == children){ totalSize.set(0); return; } for (final File child : children) { //文件:直接加當前文件的大小 if (child.isFile()) fileSize += child.length(); //文件夾:遍歷裏面的文件的大小 else { pendingFileVisits.incrementAndGet();//增長一個當前值(用來觀察這裏的線程是否啓動) service.execute(new Runnable() { public void run() { updateTotalSizeOfFilesInDir(child); } }); } } } totalSize.addAndGet(fileSize); //若是沒有遍歷子文件夾,則pendingFileVisits-1 = 0,須要啓動線程 if (pendingFileVisits.decrementAndGet() == 0) latch.countDown();//啓動全部等待的線程 } /** * 獲得指定文件的大小 * @param fileName 文件名(全路徑) * @return 文件夾大小(M) * @throws InterruptedException */ public double getTotalSizeOfFile(final String fileName){ service = Executors.newFixedThreadPool(100);//初始化線程池 pendingFileVisits.incrementAndGet();//增長當前值1 double result = 0;//初始化結果 try { updateTotalSizeOfFilesInDir(new File(fileName)); latch.await(100, TimeUnit.SECONDS);//當前線程等待,直到鎖存器計數到0 //將k轉換成m long resultK = totalSize.longValue(); BigDecimal bdK = new BigDecimal(resultK); BigDecimal bdM = bdK.divide(new BigDecimal(1024 * 1024)).setScale(5, RoundingMode.HALF_UP);//保留5位小數 result = bdM.doubleValue(); }catch (InterruptedException e) { e.printStackTrace(); }finally { service.shutdown(); } return result; } }
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); } }
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); } }