日本综合一区二区|亚洲中文天堂综合|日韩欧美自拍一区|男女精品天堂一区|欧美自拍第6页亚洲成人精品一区|亚洲黄色天堂一区二区成人|超碰91偷拍第一页|日韩av夜夜嗨中文字幕|久久蜜综合视频官网|精美人妻一区二区三区

(一)單線程遞歸方式

創(chuàng)新互聯(lián)建站專注于企業(yè)營銷型網(wǎng)站、網(wǎng)站重做改版、橫山網(wǎng)站定制設(shè)計、自適應品牌網(wǎng)站建設(shè)、html5、商城網(wǎng)站定制開發(fā)、集團公司官網(wǎng)建設(shè)、外貿(mào)營銷網(wǎng)站建設(shè)、高端網(wǎng)站制作、響應式網(wǎng)頁設(shè)計等建站業(yè)務(wù)，價格優(yōu)惠性價比高，為橫山等各大城市提供網(wǎng)站開發(fā)制作服務(wù)。

 
 

  
  
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); 
  
  
    } 
  
  
} 
 
 

 

(二)使用Executors.newFixedThreadPool和callable 多線程實現(xiàn)

 
 

  
  
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 subDirectories; 
  
  
        public SubDirectoriesAndSize(final long totalSize, 
  
  
                final List theSubDirs) { 
  
  
            size = totalSize; 
  
  
            subDirectories = Collections.unmodifiableList(theSubDirs); 
  
  
        } 
  
  
    } 
  
  
    private SubDirectoriesAndSize getTotalAndSubDirs(final File file) { 
  
  
        long total = 0; 
  
  
        final List subDirectories = new ArrayList(); 
  
  
        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 directories = new ArrayList(); 
  
  
            directories.add(file); 
  
  
            while (!directories.isEmpty()) { 
  
  
                final List> partialResults = new ArrayList>(); 
  
  
                for (final File directory : directories) { 
  
  
                    partialResults.add(service 
  
  
                            .submit(new Callable() { 
  
  
                                public SubDirectoriesAndSize call() { 
  
  
                                    return getTotalAndSubDirs(directory); 
  
  
                                } 
  
  
                            })); 
  
  
                } 
  
  
                directories.clear(); 
  
  
                for (final Future 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); 
  
  
    } 
  
  
} 
 
 

 

(三)使用Executors.newFixedThreadPool和callable 多線程的另外一種實現(xiàn)

 
 

  
  
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> partialTotalFutures = new ArrayList>(); 
  
  
            for (final File child : children) { 
  
  
                partialTotalFutures.add(service.submit(new Callable() { 
  
  
                    public Long call() throws InterruptedException, 
  
  
                            ExecutionException, TimeoutException { 
  
  
                        return getTotalSizeOfFilesInDir(service, child); 
  
  
                    } 
  
  
                })); 
  
  
            } 
  
  
            for (final Future 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); 
  
  
    } 
  
  
} 
 
 

#p#

(四)使用CountDownLatch和AtomicLong實現(xiàn)多線程下的并發(fā)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的實現(xiàn)

 
 

  
  
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 fileSizes = new ArrayBlockingQueue( 
  
  
            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來實現(xiàn)

 
 

  
  
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 { 
  
  
        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> tasks = new ArrayList>(); 
  
  
                    for (final File child : children) { 
  
  
                        if (child.isFile()) { 
  
  
                            size += child.length(); 
  
  
                        } else { 
  
  
                            tasks.add(new FileSizeFinder(child)); 
  
  
                        } 
  
  
                    } 
  
  
                    for (final ForkJoinTask 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); 
  
  
    } 
  
  
} 
 
 

當前名稱：Java讀取文件夾大小的6種方法及代碼
文章轉(zhuǎn)載：http://www.dlmjj.cn/article/djhgedd.html