Java reading folder size several method instances _java

(i) Single-threaded recursive method

Copy Code code as follows:

Package com.taobao.test;

Import Java.io.File;

public class Totalfilesizesequential {

public static String FileName = "C:\\Documents and settings\\administrator\\ desktop \\monkeytalk";

Recursively calculate the size of a file
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);
}
}

(ii) using Executors.newfixedthreadpool and callable multithread implementations

Copy Code code as follows:

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\\ desktop \\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&lt;file&gt; subdirectories = new arraylist&lt;file&gt; ();


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 to 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&lt;file&gt; directories = new arraylist&lt;file&gt; ();


Directories.add (file);


while (!directories.isempty ()) {


Final list&lt;future&lt;subdirectoriesandsize&gt;&gt; partialresults = new arraylist&lt;future&lt; Subdirectoriesandsize&gt;&gt; ();


For (final File directory:directories) {


Partialresults.add (Service


. Submit (New callable&lt;subdirectoriesandsize&gt; () {


Public Subdirectoriesandsize call () {


return Gettotalandsubdirs (directory);


}


}));


}


Directories.clear ();


For (final future&lt;subdirectoriesandsize&gt; partialresultfuture:partialresults) {


Final Subdirectoriesandsize subdirectoriesandsize = partialresultfuture


. get (MB, 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);
}
}

(iii) Another implementation that uses Executors.newfixedthreadpool and callable multiple threads

Copy Code code as follows:

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\\ desktop \\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&lt;future&lt;long&gt;&gt; partialtotalfutures = new arraylist&lt;future&lt;long&gt;&gt; ();


For (final File Child:children) {


Partialtotalfutures.add (Service.submit (New callable&lt;long&gt; ()) {


Public Long Call () throws Interruptedexception,


Executionexception, TimeoutException {


return Gettotalsizeoffilesindir (service, child);


}


}));


}

For (final future<long> partialtotalfuture:partialtotalfutures)
Total + = Partialtotalfuture.get (M, 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);
}
}

(iv) using Countdownlatch and Atomiclong to implement concurrent control under multithreading

Copy Code code as follows:

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\\ desktop \\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 (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);
}
}

(v) Use of blockingqueue and Atomiclong implementations

Copy Code code as follows:

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\\ desktop \\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 () &gt; 0 | | filesizes.size () &gt; 0) {


Final Long size = Filesizes.poll (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);
}
}

(vi) Use of JDK7 forkjoin to achieve

Copy Code code as follows:

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\\ desktop \\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&lt;forkjointask&lt;long&gt;&gt; tasks = new arraylist&lt;forkjointask&lt;long&gt;&gt; ();


For (final File Child:children) {


if (Child.isfile ()) {


Size + = Child.length ();


} else {


Tasks.add (New Filesizefinder (child));


}


}


For (final forkjointask&lt;long&gt; 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 ("/home"));
Final Long end = System.nanotime ();
System.out.println ("Total Size:" + total);
System.out.println ("Time Taken:" + (End-start)/1.0e9);
}
}