blocks|key|1291130|text|假设这是您将要编写的实际生产代码，那么我建议使用已经解决这类问题的解决方案-+Apache+Commons+IO，特别是FileUtils.listFiles()。它处理嵌套目录、过滤器(基于名称、修改时间等)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1291131|例如，对于您的正则表达式：|1291132|Collection+files+=+FileUtils.listFiles(
++dir,+
++new+RegexFileFilter("%5E(.*?)"),+
++DirectoryFileFilter.DIRECTORY
);|code-block|syntax|javascript|1291133|这将递归地搜索与%5E(.*?)正则表达式匹配的文件，并将结果作为集合返回。|1291134|值得注意的是，这不会比滚动您自己的代码更快，它做的是相同的事情-在Java中拖拽文件系统只是很慢。不同的是，Apache+Commons版本中没有bug。|1291135|entityMap|0|LINK|mutability|MUTABLE|url|http://commons.apache.org/proper/commons-io/|1|http://commons.apache.org/proper/commons-io/javadocs/api-release/org/apache/commons/io/FileUtils.html#listFiles%2528java.io.File,%2520org.apache.commons.io.filefilter.IOFileFilter,%2520org.apache.commons.io.filefilter.IOFileFilter%2529^0|1O|L|13|H|0|1O|L|1|0|0|0|8|6|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@$9|11|A|12|B|C]]|D|@$9|13|A|14|1|15]|$9|16|A|17|1|18]]|E|$]]|$1|F|3|G|5|6|7|19|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|1A|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1B|8|@$9|1C|A|1D|B|C]]|D|@]|E|$]]|$1|O|3|P|5|6|7|1E|8|@]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|1F|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]|Y|$5|T|U|V|E|$W|Z]]]]

Assuming this is actual production code you'll be writing, then I suggest using the solution to this sort of thing that's already been solved - <a href="http://commons.apache.org/proper/commons-io/" rel="noreferrer">Apache Commons IO</a>, specifically <a href="http://commons.apache.org/proper/commons-io/javadocs/api-release/org/apache/commons/io/FileUtils.html#listFiles%28java.io.File,%20org.apache.commons.io.filefilter.IOFileFilter,%20org.apache.commons.io.filefilter.IOFileFilter%29" rel="noreferrer"><code>FileUtils.listFiles()</code></a>. It handles nested directories, filters (based on name, modification time, etc).

For example, for your regex:

<pre><code>Collection files = FileUtils.listFiles(
 dir, 
 new RegexFileFilter("^(.*?)"), 
 DirectoryFileFilter.DIRECTORY
);
</code></pre>

This will recursively search for files matching the <code>^(.*?)</code> regex, returning the results as a collection.

It's worth noting that this will be no faster than rolling your own code, it's doing the same thing - trawling a filesystem in Java is just slow. The difference is, the Apache Commons version will have no bugs in it.

blocks|key|1076213|text|Java用于读取文件系统文件夹内容的接口性能不是很好(正如您已经发现的)。JDK+7为这类事情提供了一个全新的接口来修复这个问题，这应该会为这类操作带来本机级别的性能。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1076214|核心问题是Java对每个单独的文件进行本机系统调用。在低延迟接口上，这并不是什么大问题-但在一个即使是中等延迟的网络上，这也是非常重要的。如果您在上面描述了您的算法，您会发现大部分时间都花在烦人的isDirectory()调用上--这是因为您每次调用isDirectory()都要经历一次往返。大多数现代OSes可以在最初请求文件/文件夹列表时提供此类信息(而不是查询每个单独的文件路径以获取其属性)。|1076215|如果你不能等待JDK7，解决这个延迟的一个策略是多线程，并使用一个具有最大线程数的ExecutorService来执行你的递归。这不是很好(您必须处理输出数据结构的锁定)，但它将比使用单线程快得多。|1076216|在所有关于这类事情的讨论中，我强烈建议您与使用本机代码(甚至是做大致相同事情的命令行脚本)的最佳效果进行比较。说需要一个小时来遍历一个网络结构并不意味着太多。告诉我们你可以在7秒内完成，但在Java中需要一个小时，这会引起人们的注意。|1076217|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

Java's interface for reading filesystem folder contents is not very performant (as you've discovered). JDK 7 fixes this with a completely new interface for this sort of thing, which should bring native level performance to these sorts of operations.

The core issue is that Java makes a native system call for every single file. On a low latency interface, this is not that big of a deal - but on a network with even moderate latency, it really adds up. If you profile your algorithm above, you'll find that the bulk of the time is spent in the pesky isDirectory() call - that's because you are incurring a round trip for every single call to isDirectory(). Most modern OSes can provide this sort of information when the list of files/folders was originally requested (as opposed to querying each individual file path for it's properties).

If you can't wait for JDK7, one strategy for addressing this latency is to go multi-threaded and use an ExecutorService with a maximum # of threads to perform your recursion. It's not great (you have to deal with locking of your output data structures), but it'll be a heck of a lot faster than doing this single threaded.

In all of your discussions about this sort of thing, I highly recommend that you compare against the best you could do using native code (or even a command line script that does roughly the same thing). Saying that it takes an hour to traverse a network structure doesn't really mean that much. Telling us that you can do it native in 7 second, but it takes an hour in Java will get people's attention.

blocks|key|1291232|text|如您所知，isDirectory()是一种相当慢的方法。我发现它在我的文件浏览器中相当慢。我将研究一个库，将其替换为本机代码。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1291233|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Just so you know isDirectory() is quite a slow method. I'm finding it quite slow in my file browser. I'll be looking into a library to replace it with native code.

blocks|key|1076310|text|在处理数百万个文件夹和文件时，我发现更有效的方法是通过DOS命令在某些文件中捕获目录列表并对其进行解析。一旦你解析了数据，你就可以进行分析和计算统计数据。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1076311|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

The more efficient way I found in dealing with millions of folders and files is to capture directory listing through DOS command in some file and parse it. Once you have parsed data then you can do analysis and compute statistics.

blocks|key|1076356|text|此函数可能会列出其目录及其子目录中的所有文件名及其路径。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1076357|public+void+listFile(String+pathname)+{
++++File+f+=+new+File(pathname);
++++File[]+listfiles+=+f.listFiles();
++++for+(int+i+=+0;+i+<+listfiles.length;+i%2B%2B)+{
++++++++if+(listfiles[i].isDirectory())+{
++++++++++++File[]+internalFile+=+listfiles[i].listFiles();
++++++++++++for+(int+j+=+0;+j+<+internalFile.length;+j%2B%2B)+{
++++++++++++++++System.out.println(internalFile[j]);
++++++++++++++++if+(internalFile[j].isDirectory())+{
++++++++++++++++++++String+name+=+internalFile[j].getAbsolutePath();
++++++++++++++++++++listFile(name);
++++++++++++++++}

++++++++++++}
++++++++}+else+{
++++++++++++System.out.println(listfiles[i]);
++++++++}

++++}

}|code-block|syntax|javascript|1076358|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This Function will probably list all the file name and its path from its directory and its subdirectories. 

<pre><code>public void listFile(String pathname) {
 File f = new File(pathname);
 File[] listfiles = f.listFiles();
 for (int i = 0; i &lt; listfiles.length; i++) {
 if (listfiles[i].isDirectory()) {
 File[] internalFile = listfiles[i].listFiles();
 for (int j = 0; j &lt; internalFile.length; j++) {
 System.out.println(internalFile[j]);
 if (internalFile[j].isDirectory()) {
 String name = internalFile[j].getAbsolutePath();
 listFile(name);
 }

 }
 } else {
 System.out.println(listfiles[i]);
 }

 }

}
</code></pre>

blocks|key|1291393|text|使用Java+7+NIO获取目录内容的快速方法是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1291394|import+java.nio.file.DirectoryStream;
import+java.nio.file.Files;
import+java.nio.file.FileSystems;
import+java.nio.file.Path;

...

Path+dir+=+FileSystems.getDefault().getPath(+filePath+);
DirectoryStream<Path>+stream+=+Files.newDirectoryStream(+dir+);
for+(Path+path+:+stream)+{
+++System.out.println(+path.getFileName()+);
}
stream.close();|code-block|syntax|javascript|1291395|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

The fast way to get the content of a directory using Java 7 NIO :

<pre><code>import java.nio.file.DirectoryStream;
import java.nio.file.Files;
import java.nio.file.FileSystems;
import java.nio.file.Path;

...

Path dir = FileSystems.getDefault().getPath( filePath );
DirectoryStream&lt;Path&gt; stream = Files.newDirectoryStream( dir );
for (Path path : stream) {
 System.out.println( path.getFileName() );
}
stream.close();
</code></pre>

blocks|key|1291499|text|在Java7中，通过Paths和Files功能引入了一种更快的遍历目录树的方法。它们比“老的”File方式快得多。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1291500|下面是使用正则表达式遍历和检查路径名的代码：|1291501|public+final+void+test()+throws+IOException,+InterruptedException+{
++++final+Path+rootDir+=+Paths.get("path+to+your+directory+where+the+walk+starts");

++++//+Walk+thru+mainDir+directory
++++Files.walkFileTree(rootDir,+new+FileVisitor<Path>()+{
++++++++//+First+(minor)+speed+up.+Compile+regular+expression+pattern+only+one+time.
++++++++private+Pattern+pattern+=+Pattern.compile("%5E(.*?)");

++++++++@Override
++++++++public+FileVisitResult+preVisitDirectory(Path+path,
++++++++++++++++BasicFileAttributes+atts)+throws+IOException+{

++++++++++++boolean+matches+=+pattern.matcher(path.toString()).matches();

++++++++++++//+TODO:+Put+here+your+business+logic+when+matches+equals+true/false

++++++++++++return+(matches)?+FileVisitResult.CONTINUE:FileVisitResult.SKIP_SUBTREE;
++++++++}

++++++++@Override
++++++++public+FileVisitResult+visitFile(Path+path,+BasicFileAttributes+mainAtts)
++++++++++++++++throws+IOException+{

++++++++++++boolean+matches+=+pattern.matcher(path.toString()).matches();

++++++++++++//+TODO:+Put+here+your+business+logic+when+matches+equals+true/false

++++++++++++return+FileVisitResult.CONTINUE;
++++++++}

++++++++@Override
++++++++public+FileVisitResult+postVisitDirectory(Path+path,
++++++++++++++++IOException+exc)+throws+IOException+{
++++++++++++//+TODO+Auto-generated+method+stub
++++++++++++return+FileVisitResult.CONTINUE;
++++++++}

++++++++@Override
++++++++public+FileVisitResult+visitFileFailed(Path+path,+IOException+exc)
++++++++++++++++throws+IOException+{
++++++++++++exc.printStackTrace();

++++++++++++//+If+the+root+directory+has+failed+it+makes+no+sense+to+continue
++++++++++++return+path.equals(rootDir)?+FileVisitResult.TERMINATE:FileVisitResult.CONTINUE;
++++++++}
++++});
}|code-block|syntax|javascript|1291502|entityMap^0|A|5|G|5|1B|4|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|W|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|X|8|@]|D|@]|E|$]]]|N|$]]

With Java 7 a faster way to walk thru a directory tree was introduced with the <code>Paths</code> and <code>Files</code> functionality. They're much faster then the "old" <code>File</code> way.

This would be the code to walk thru and check path names with a regular expression:

<pre><code>public final void test() throws IOException, InterruptedException {
 final Path rootDir = Paths.get("path to your directory where the walk starts");

 // Walk thru mainDir directory
 Files.walkFileTree(rootDir, new FileVisitor&lt;Path&gt;() {
 // First (minor) speed up. Compile regular expression pattern only one time.
 private Pattern pattern = Pattern.compile("^(.*?)");

 @Override
 public FileVisitResult preVisitDirectory(Path path,
 BasicFileAttributes atts) throws IOException {

 boolean matches = pattern.matcher(path.toString()).matches();

 // TODO: Put here your business logic when matches equals true/false

 return (matches)? FileVisitResult.CONTINUE:FileVisitResult.SKIP_SUBTREE;
 }

 @Override
 public FileVisitResult visitFile(Path path, BasicFileAttributes mainAtts)
 throws IOException {

 boolean matches = pattern.matcher(path.toString()).matches();

 // TODO: Put here your business logic when matches equals true/false

 return FileVisitResult.CONTINUE;
 }

 @Override
 public FileVisitResult postVisitDirectory(Path path,
 IOException exc) throws IOException {
 // TODO Auto-generated method stub
 return FileVisitResult.CONTINUE;
 }

 @Override
 public FileVisitResult visitFileFailed(Path path, IOException exc)
 throws IOException {
 exc.printStackTrace();

 // If the root directory has failed it makes no sense to continue
 return path.equals(rootDir)? FileVisitResult.TERMINATE:FileVisitResult.CONTINUE;
 }
 });
}
</code></pre>

blocks|key|1291574|text|这是一个非常简单的递归方法，可以从给定的根目录获取所有文件。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1291575|它使用Java7NIO+Path类。|1291576|private+List<String>+getFileNames(List<String>+fileNames,+Path+dir)+{
++++try(DirectoryStream<Path>+stream+=+Files.newDirectoryStream(dir))+{
++++++++for+(Path+path+:+stream)+{
++++++++++++if(path.toFile().isDirectory())+{
++++++++++++++++getFileNames(fileNames,+path);
++++++++++++}+else+{
++++++++++++++++fileNames.add(path.toAbsolutePath().toString());
++++++++++++++++System.out.println(path.getFileName());
++++++++++++}
++++++++}
++++}+catch(IOException+e)+{
++++++++e.printStackTrace();
++++}
++++return+fileNames;
}+|code-block|syntax|javascript|1291577|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

This is a very simple recursive method to get all files from a given root.

It uses the Java 7 NIO Path class.

<pre><code>private List&lt;String&gt; getFileNames(List&lt;String&gt; fileNames, Path dir) {
 try(DirectoryStream&lt;Path&gt; stream = Files.newDirectoryStream(dir)) {
 for (Path path : stream) {
 if(path.toFile().isDirectory()) {
 getFileNames(fileNames, path);
 } else {
 fileNames.add(path.toAbsolutePath().toString());
 System.out.println(path.getFileName());
 }
 }
 } catch(IOException e) {
 e.printStackTrace();
 }
 return fileNames;
} 
</code></pre>

blocks|key|1076646|text|这将工作得很好..。和它的递归|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1076647|File+root+=+new+File("ROOT+PATH");
for+(+File+file+:+root.listFiles())
{
++++getFilesRecursive(file);
}


private+static+void+getFilesRecursive(File+pFile)
{
++++for(File+files+:+pFile.listFiles())
++++{
++++++++if(files.isDirectory())
++++++++{
++++++++++++getFilesRecursive(files);
++++++++}
++++++++else
++++++++{
++++++++++++//+do+your+thing+
++++++++++++//+you+can+either+save+in+HashMap+and+use+it+as
++++++++++++//+per+your+requirement
++++++++}
++++}
}|code-block|syntax|javascript|1076648|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

this will work just fine ... and its recursive 

<pre><code>File root = new File("ROOT PATH");
for ( File file : root.listFiles())
{
 getFilesRecursive(file);
}


private static void getFilesRecursive(File pFile)
{
 for(File files : pFile.listFiles())
 {
 if(files.isDirectory())
 {
 getFilesRecursive(files);
 }
 else
 {
 // do your thing 
 // you can either save in HashMap and use it as
 // per your requirement
 }
 }
}
</code></pre>

blocks|key|1291654|text|这将工作得很好。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1291655|public+void+displayAll(File+path){++++++
++++if(path.isFile()){
++++++++System.out.println(path.getName());
++++}else{
++++++++System.out.println(path.getName());+++++++++
++++++++File+files[]+=+path.listFiles();
++++++++for(File+dirOrFile:+files){
++++++++++++displayAll(dirOrFile);
++++++++}
++++}
}|code-block|syntax|javascript|1291656|​|1291657|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

This will work fine

<pre><code>public void displayAll(File path){ 
 if(path.isFile()){
 System.out.println(path.getName());
 }else{
 System.out.println(path.getName()); 
 File files[] = path.listFiles();
 for(File dirOrFile: files){
 displayAll(dirOrFile);
 }
 }
}
</code></pre>

blocks|key|1076743|text|我个人喜欢这个版本的FileUtils。下面是一个查找某个目录或其任何子目录中所有mp3s或flacs的示例：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1076744|String[]+types+=+{"mp3",+"flac"};
Collection<File>+files2+=+FileUtils.listFiles(/path/to/your/dir,+types+,+true);|code-block|syntax|javascript|1076745|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I personally like this version of FileUtils. Here's an example that finds all mp3s or flacs in a directory or any of its subdirectories:

<pre><code>String[] types = {"mp3", "flac"};
Collection&lt;File&gt; files2 = FileUtils.listFiles(/path/to/your/dir, types , true);
</code></pre>

blocks|key|1076771|text|import+java.io.*;

public+class+MultiFolderReading+{

public+void+checkNoOfFiles+(String+filename)+throws+IOException+{

++++File+dir=new+File(filename);
++++File+files[]=dir.listFiles();//files+array+stores+the+list+of+files

+for(int+i=0;i<files.length;i%2B%2B)
++++{
++++++++if(files[i].isFile())+//check+whether+files[i]+is+file+or+directory
++++++++{
++++++++++++System.out.println("File::"%2Bfiles[i].getName());
++++++++++++System.out.println();

++++++++}
++++++++else+if(files[i].isDirectory())
++++++++{
++++++++++++System.out.println("Directory::"%2Bfiles[i].getName());
++++++++++++System.out.println();
++++++++++++checkNoOfFiles(files[i].getAbsolutePath());
++++++++}
++++}
}

public+static+void+main(String[]+args)+throws+IOException+{

++++MultiFolderReading+mf=new+MultiFolderReading();
++++String+str="E:\\file";+
++++mf.checkNoOfFiles(str);
+++}
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1076772|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>import java.io.*;

public class MultiFolderReading {

public void checkNoOfFiles (String filename) throws IOException {

 File dir=new File(filename);
 File files[]=dir.listFiles();//files array stores the list of files

 for(int i=0;i&lt;files.length;i++)
 {
 if(files[i].isFile()) //check whether files[i] is file or directory
 {
 System.out.println("File::"+files[i].getName());
 System.out.println();

 }
 else if(files[i].isDirectory())
 {
 System.out.println("Directory::"+files[i].getName());
 System.out.println();
 checkNoOfFiles(files[i].getAbsolutePath());
 }
 }
}

public static void main(String[] args) throws IOException {

 MultiFolderReading mf=new MultiFolderReading();
 String str="E:\\file"; 
 mf.checkNoOfFiles(str);
 }
}
</code></pre>

blocks|key|1291763|text|在Java8中，它是一个通过Files.find()的1行代码，具有任意大的深度(例如999)和BasicFileAttributes+of+isRegularFile()|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1291764|public+static+printFnames(String+sDir)+{
++++Files.find(Paths.get(sDir),+999,+(p,+bfa)+->+bfa.isRegularFile()).forEach(System.out::println);
}|code-block|syntax|javascript|1291765|要添加更多过滤，请增强lambda，例如在过去24小时内修改的所有jpg文件：|1291766|(p,+bfa)+->+bfa.isRegularFile()
++&&+p.getFileName().toString().matches(".*\\.jpg")
++&&+bfa.lastModifiedTime().toMillis()+>+System.currentMillis()+-+86400000|1291767|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.oracle.com/javase/8/docs/api/java/nio/file/Files.html#find-java.nio.file.Path-int-java.util.function.BiPredicate-java.nio.file.FileVisitOption...-|1|https://docs.oracle.com/javase/8/docs/api/java/nio/file/attribute/BasicFileAttributes.html|2|https://docs.oracle.com/javase/8/docs/api/java/nio/file/attribute/BasicFileAttributes.html#isRegularFile--^0|E|C|17|3|1C|J|1Z|F|E|C|0|1C|J|1|1Z|F|2|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@$9|11|A|12|B|C]|$9|13|A|14|B|C]|$9|15|A|16|B|C]|$9|17|A|18|B|C]]|D|@$9|19|A|1A|1|1B]|$9|1C|A|1D|1|1E]|$9|1F|A|1G|1|1H]]|E|$]]|$1|F|3|G|5|H|7|1I|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1J|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|1K|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|1L|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]|W|$5|R|S|T|E|$U|X]]|Y|$5|R|S|T|E|$U|Z]]]]

In Java 8, it's a 1-liner via <a href="https://docs.oracle.com/javase/8/docs/api/java/nio/file/Files.html#find-java.nio.file.Path-int-java.util.function.BiPredicate-java.nio.file.FileVisitOption...-"><code>Files.find()</code></a> with an arbitrarily large depth (eg <code>999</code>) and <a href="https://docs.oracle.com/javase/8/docs/api/java/nio/file/attribute/BasicFileAttributes.html"><code>BasicFileAttributes</code></a> of <a href="https://docs.oracle.com/javase/8/docs/api/java/nio/file/attribute/BasicFileAttributes.html#isRegularFile--"><code>isRegularFile()</code></a>

<pre><code>public static printFnames(String sDir) {
 Files.find(Paths.get(sDir), 999, (p, bfa) -&gt; bfa.isRegularFile()).forEach(System.out::println);
}
</code></pre>

To add more filtering, enhance the lambda, for example all jpg files modified in the last 24 hours:

<pre><code>(p, bfa) -&gt; bfa.isRegularFile()
 &amp;&amp; p.getFileName().toString().matches(".*\\.jpg")
 &amp;&amp; bfa.lastModifiedTime().toMillis() &gt; System.currentMillis() - 86400000
</code></pre>

blocks|key|1076884|text|在Guava中，您不必等待Collection返回给您，但实际上可以遍历文件。在下面函数的签名中很容易想象出一个IDoSomethingWithThisFile接口：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1076885|public+static+void+collectFilesInDir(File+dir)+{
++++TreeTraverser<File>+traverser+=+Files.fileTreeTraverser();
++++FluentIterable<File>+filesInPostOrder+=+traverser.preOrderTraversal(dir);
++++for+(File+f:+filesInPostOrder)
++++++++System.out.printf("File:+%25s\n",+f.getPath());
}|code-block|syntax|javascript|1076886|TreeTraverser还允许您在不同的遍历样式之间切换。|1076887|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/collect/TreeTraverser.html^0|1K|O|0|0|0|D|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|Y|8|@]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|M|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

In Guava you don't have to wait for a Collection to be returned to you but can actually iterate over the files. It is easy to imagine a <code>IDoSomethingWithThisFile</code> interface in the signature of the below function:

<pre><code>public static void collectFilesInDir(File dir) {
 TreeTraverser&lt;File&gt; traverser = Files.fileTreeTraverser();
 FluentIterable&lt;File&gt; filesInPostOrder = traverser.preOrderTraversal(dir);
 for (File f: filesInPostOrder)
 System.out.printf("File: %s\n", f.getPath());
}
</code></pre>

<a href="http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/collect/TreeTraverser.html" rel="nofollow">TreeTraverser</a> also allows you to between various traversal styles.

blocks|key|1291816|text|public+class+GetFilesRecursive+{
++++public+static+List+<String>+getFilesRecursively(File+dir){
++++++++List+<String>+ls+=+new+ArrayList<String>();
++++++++for+(File+fObj+:+dir.listFiles())+{
++++++++++++if(fObj.isDirectory())+{
++++++++++++++++ls.add(String.valueOf(fObj));
++++++++++++++++ls.addAll(getFilesRecursively(fObj));+++++++++++++++
++++++++++++}+else+{
++++++++++++++++ls.add(String.valueOf(fObj));+++++++
++++++++++++}
++++++++}

++++++++return+ls;
++++}
++++public+static+List+<String>+getListOfFiles(String+fullPathDir)+{
++++++++List+<String>+ls+=+new+ArrayList<String>+();
++++++++File+f+=+new+File(fullPathDir);
++++++++if+(f.exists())+{
++++++++++++if(f.isDirectory())+{
++++++++++++++++ls.add(String.valueOf(f));
++++++++++++++++ls.addAll(getFilesRecursively(f));
++++++++++++}
++++++++}+else+{
++++++++++++ls.add(fullPathDir);
++++++++}
++++++++return+ls;
++++}

++++public+static+void+main(String[]+args)+{
++++++++List+<String>+ls+=+getListOfFiles("/Users/srinivasab/Documents");
++++++++for+(String+file:ls)+{
++++++++++++System.out.println(file);
++++++++}
++++++++System.out.println(ls.size());
++++}
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1291817|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>public class GetFilesRecursive {
 public static List &lt;String&gt; getFilesRecursively(File dir){
 List &lt;String&gt; ls = new ArrayList&lt;String&gt;();
 for (File fObj : dir.listFiles()) {
 if(fObj.isDirectory()) {
 ls.add(String.valueOf(fObj));
 ls.addAll(getFilesRecursively(fObj)); 
 } else {
 ls.add(String.valueOf(fObj)); 
 }
 }

 return ls;
 }
 public static List &lt;String&gt; getListOfFiles(String fullPathDir) {
 List &lt;String&gt; ls = new ArrayList&lt;String&gt; ();
 File f = new File(fullPathDir);
 if (f.exists()) {
 if(f.isDirectory()) {
 ls.add(String.valueOf(f));
 ls.addAll(getFilesRecursively(f));
 }
 } else {
 ls.add(fullPathDir);
 }
 return ls;
 }

 public static void main(String[] args) {
 List &lt;String&gt; ls = getListOfFiles("/Users/srinivasab/Documents");
 for (String file:ls) {
 System.out.println(file);
 }
 System.out.println(ls.size());
 }
}
</code></pre>

blocks|key|1076934|text|另一个优化的代码|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1076935|import+java.io.File;
import+java.util.ArrayList;
import+java.util.List;

public+class+GetFilesRecursive+{
++++public+static+List+<String>+getFilesRecursively(File+dir){
++++++++List+<String>+ls+=+new+ArrayList<String>();
++++++++if+(dir.isDirectory())
++++++++++++for+(File+fObj+:+dir.listFiles())+{
++++++++++++++++if(fObj.isDirectory())+{
++++++++++++++++++++ls.add(String.valueOf(fObj));
++++++++++++++++++++ls.addAll(getFilesRecursively(fObj));+++++++++++++++
++++++++++++++++}+else+{
++++++++++++++++++++ls.add(String.valueOf(fObj));+++++++
++++++++++++++++}
++++++++++++}
++++++++else
++++++++++++ls.add(String.valueOf(dir));

++++++++return+ls;
++++}

++++public+static+void+main(String[]+args)+{
++++++++List+<String>+ls+=+getFilesRecursively(new+File("/Users/srinivasab/Documents"));
++++++++for+(String+file:ls)+{
++++++++++++System.out.println(file);
++++++++}
++++++++System.out.println(ls.size());
++++}
}|code-block|syntax|javascript|1076936|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Another optimized code

<pre><code>import java.io.File;
import java.util.ArrayList;
import java.util.List;

public class GetFilesRecursive {
 public static List &lt;String&gt; getFilesRecursively(File dir){
 List &lt;String&gt; ls = new ArrayList&lt;String&gt;();
 if (dir.isDirectory())
 for (File fObj : dir.listFiles()) {
 if(fObj.isDirectory()) {
 ls.add(String.valueOf(fObj));
 ls.addAll(getFilesRecursively(fObj)); 
 } else {
 ls.add(String.valueOf(fObj)); 
 }
 }
 else
 ls.add(String.valueOf(dir));

 return ls;
 }

 public static void main(String[] args) {
 List &lt;String&gt; ls = getFilesRecursively(new File("/Users/srinivasab/Documents"));
 for (String file:ls) {
 System.out.println(file);
 }
 System.out.println(ls.size());
 }
}
</code></pre>

blocks|key|1076975|text|使用Java8+filter列出文件和目录的另一个示例|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1076976|public+static+void+main(String[]+args)+{

System.out.println("Files!!");
++++++++try+{
++++++++++++Files.walk(Paths.get("."))
++++++++++++++++++++.filter(Files::isRegularFile)
++++++++++++++++++++.filter(c+->
++++++++++++++++++++++++++++c.getFileName().toString().substring(c.getFileName().toString().length()-4).contains(".jpg")
++++++++++++++++++++++++++++%7C%7C
++++++++++++++++++++++++++++c.getFileName().toString().substring(c.getFileName().toString().length()-5).contains(".jpeg")
++++++++++++++++++++)
++++++++++++++++++++.forEach(System.out::println);

++++++++}+catch+(IOException+e)+{
++++++++System.out.println("No+jpeg+or+jpg+files");
++++++++}

++++++++System.out.println("\nDirectories!!\n");
++++++++try+{
++++++++++++Files.walk(Paths.get("."))
++++++++++++++++++++.filter(Files::isDirectory)
++++++++++++++++++++.forEach(System.out::println);

++++++++}+catch+(IOException+e)+{
++++++++++++System.out.println("No+Jpeg+files");
++++++++}
}|code-block|syntax|javascript|1076977|entityMap^0|8|6|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

One more example of listing files and directories using Java 8 <code>filter</code>
<pre><code>public static void main(String[] args) {

System.out.println(&quot;Files!!&quot;);
 try {
 Files.walk(Paths.get(&quot;.&quot;))
 .filter(Files::isRegularFile)
 .filter(c -&gt;
 c.getFileName().toString().substring(c.getFileName().toString().length()-4).contains(&quot;.jpg&quot;)
 ||
 c.getFileName().toString().substring(c.getFileName().toString().length()-5).contains(&quot;.jpeg&quot;)
 )
 .forEach(System.out::println);

 } catch (IOException e) {
 System.out.println(&quot;No jpeg or jpg files&quot;);
 }

 System.out.println(&quot;\nDirectories!!\n&quot;);
 try {
 Files.walk(Paths.get(&quot;.&quot;))
 .filter(Files::isDirectory)
 .forEach(System.out::println);

 } catch (IOException e) {
 System.out.println(&quot;No Jpeg files&quot;);
 }
}
</code></pre>

I have this function that prints the name of all the files in a directory recursively. The problem is that my code is very slow because it has to access a remote network device with every iteration.
My plan is to first load all the files from the directory recursively and then after that go through all files with the regex to filter out all the files I don't want. Does anyone have a better suggestion?
<pre class="lang-java prettyprint-override"><code>public static printFnames(String sDir) {
 File[] faFiles = new File(sDir).listFiles();
 for (File file : faFiles) {
 if (file.getName().matches(&quot;^(.*?)&quot;)) {
 System.out.println(file.getAbsolutePath());
 }
   if (file.isDirectory()) {
 printFnames(file.getAbsolutePath());
 }
 }
}
</code></pre>
This is just a test later on I'm not going to use the code like this, instead I'm going to add the path and modification date of every file which matches an advanced regex to an array.

List all files from a directory recursively with Java

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我有一个递归打印目录中所有文件名称的函数。问题是我的代码非常慢，因为每次迭代它都必须访问远程网络设备。我的计划是首先递归地加载目录中的所有文件，然后使用regex遍历所有文件，以过滤掉我不需要的所有文件。有人有更好的建议吗？public static printFnames(String sDir) {    File...

问使用Java递归列出目录中的所有文件
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