java读取文件夹大小的6种方法及代码-mile米乐体育

这篇文章介绍了java读取文件夹大小的几种方法实例，有需要的朋友可以参考一下。

(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 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> 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);     } }

（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 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 {         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);     } }