Java读取文件夹大小的6种方法(收集)

说明:File.length()仅仅用于获得某个文件的大小,单位为bytes

以下提供六种方法遍历文件夹下子文件求其大小总和。

单线程递归方式

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29

import java.io.File;
public class TotalFileSize {
public static String fileName = "C:\\Users\\Administrator\\Desktop\\1_11";

// 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;
}
/**
* @param args
*/
public static void main(String[] args) {
final long start = System.nanoTime();
final long total = new TotalFileSize()
.getTotalSizeOfFilesInDir(new File(fileName));
final long end = System.nanoTime();
System.out.println("Total Size: " + total);
System.out.println("Time taken: " + (end - start) / 1.0e9);
}

}

计算结果:

Total Size: 59597673
Time taken: 0.02347729

使用Executors.newFixedThreadPool和callable 多线程实现

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84

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:\\Users\\Administrator\\Desktop\\1_11";

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);
}
}

计算结果:

Total Size: 59597673
Time taken: 0.102727254

使用Executors.newFixedThreadPool和callable 多线程的另外一种实现

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
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:\\Users\\Administrator\\Desktop\\1_11";

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);
}
}

计算结果:

Total Size: 59597673
Time taken: 0.058243242

使用CountDownLatch和AtomicLong实现多线程下的并发控制

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
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:\\Users\\Administrator\\Desktop\\1_11";

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);
}
}

计算结果:

Total Size: 59597673
Time taken: 0.026633095

使用BlockingQueue和AtomicLong的实现

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
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:\\Users\\Administrator\\Desktop\\1_11";

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);
}
}

计算结果:

Total Size: 59597673
Time taken: 0.044469408

使用jdk7的ForkJoin来实现

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
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:\\Users\\Administrator\\Desktop\\1_11";

private static class FileSizeFinder extends RecursiveTask<Long> {
/**
*
*/
private static final long serialVersionUID = 1L;
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(fileName)));
final long end = System.nanoTime();
System.out.println("Total Size: " + total);
System.out.println("Time taken: " + (end - start) / 1.0e9);
}
}

计算结果:

Total Size: 59597673
Time taken: 0.015022339

来自http://blog.csdn.net/u011277123/article/details/52980247

文章目录
  1. 单线程递归方式
  2. 使用Executors.newFixedThreadPool和callable 多线程实现
  3. 使用Executors.newFixedThreadPool和callable 多线程的另外一种实现
  4. 使用CountDownLatch和AtomicLong实现多线程下的并发控制
  5. 使用BlockingQueue和AtomicLong的实现
  6. 使用jdk7的ForkJoin来实现
本站总访问量 | 本文总阅读量