如何复制目录及其子目录，文件和zip文件

Question

I am trying to copy directories (ex: My documents, Local Disk D) with all of its contents.The code I used is below.

 public void copyFolder(File inputLocation, File outputLocation) throws IOException
    {
       // FileUtils.copyDirectory(inputLocation, outputLocation);

        if (inputLocation.isDirectory())
        {

            //if directory not exists, create it
            if (!outputLocation.exists())
            {
                outputLocation.mkdir();
                System.out.println("Directory copied from "
                        + inputLocation + "  to " + outputLocation);
            }



            //list all the directory contents
            String files[] = inputLocation.list();

            for (String file : files)
            {
                //construct the src and dest file structure
                File srcFile = new File(inputLocation, file);
                File destFile = new File(outputLocation, file);
                //recursive copy
                copyFolder(srcFile, destFile);
            }

        } else
        {
            //if file, then copy it
            //Use bytes stream to support all file types
            InputStream in = new FileInputStream(inputLocation);
            OutputStream out = new FileOutputStream(outputLocation);

            byte[] buffer = new byte[1024];

            int length;
            //copy the file content in bytes 
            while ((length = in.read(buffer)) > 0)
            {
                out.write(buffer, 0, length);
            }

            in.close();
            out.close();
            System.out.println("File copied from " + inputLocation + " to " + outputLocation);
        }
    }

This code fails as it generates an error. The error is simply happening because it "shifts" the path. The path I inserted to copy is "My Documents" and somehow it tried to copy "My Music" as well, which ended up in nullPointerException because the "My Music" is outside of "My Documents". It is also important to note that this is happening only for some input locations, not all the time.

The error I get is below.

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at xxx.xxx.xxx.xxxx.xxxxx1.copyFolder(FolderCopy.java:52)
    at xxx.xxx.xxx.xxxx.xxxxx1.FolderCopy.copyFolder(FolderCopy.java:58)
    at xxx.xxx.xxx.xxxx.xxxxx1.ExpressWizard.noCompresionCheckBoxActionPerformed(ExpressWizard.java:2481)
    at xxx.xxx.xxx.xxxx.xxxxx1.ExpressWizard.access$4900(ExpressWizard.java:38)
    at xxx.xxx.xxx.xxxx.xxxxx1.ExpressWizard$30.actionPerformed(ExpressWizard.java:1413)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2346)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.JToggleButton$ToggleButtonModel.setPressed(JToggleButton.java:308)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6525)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
    at java.awt.Component.processEvent(Component.java:6290)
    at java.awt.Container.processEvent(Container.java:2234)
    at java.awt.Component.dispatchEventImpl(Component.java:4881)
    at java.awt.Container.dispatchEventImpl(Container.java:2292)
    at java.awt.Component.dispatchEvent(Component.java:4703)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4533)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
    at java.awt.Container.dispatchEventImpl(Container.java:2278)
    at java.awt.Window.dispatchEventImpl(Window.java:2750)
    at java.awt.Component.dispatchEvent(Component.java:4703)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:751)
    at java.awt.EventQueue.access$500(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:702)
    at java.awt.EventQueue$3.run(EventQueue.java:696)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.awt.EventQueue$4.run(EventQueue.java:724)
    at java.awt.EventQueue$4.run(EventQueue.java:722)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:721)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:109)
    at java.awt.WaitDispatchSupport$2.run(WaitDispatchSupport.java:184)
    at java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:229)
    at java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:227)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.awt.WaitDispatchSupport.enter(WaitDispatchSupport.java:227)
    at java.awt.Dialog.show(Dialog.java:1084)
    at java.awt.Component.show(Component.java:1654)
    at java.awt.Component.setVisible(Component.java:1606)
    at java.awt.Window.setVisible(Window.java:1014)
    at java.awt.Dialog.setVisible(Dialog.java:1005)
    at com.theace.backupsystem.view.HomePanel.clickPanel01MouseClicked(HomePanel.java:653)
    at xxx.xxx.xxx.xxxx.xxxxx1.HomePanel.access$000(HomePanel.java:16)
    at xxx.xxx.xxx.xxxx.xxxxx1.HomePanel$1.mouseClicked(HomePanel.java:120)
    at java.awt.Component.processMouseEvent(Component.java:6528)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
    at java.awt.Component.processEvent(Component.java:6290)
    at java.awt.Container.processEvent(Container.java:2234)
    at java.awt.Component.dispatchEventImpl(Component.java:4881)
    at java.awt.Container.dispatchEventImpl(Container.java:2292)
    at java.awt.Component.dispatchEvent(Component.java:4703)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4542)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
    at java.awt.Container.dispatchEventImpl(Container.java:2278)
    at java.awt.Window.dispatchEventImpl(Window.java:2750)
    at java.awt.Component.dispatchEvent(Component.java:4703)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:751)
    at java.awt.EventQueue.access$500(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:702)
    at java.awt.EventQueue$3.run(EventQueue.java:696)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.awt.EventQueue$4.run(EventQueue.java:724)
    at java.awt.EventQueue$4.run(EventQueue.java:722)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:721)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

The line 52 is

for (String file : files)

Please help me to fix my errors .

Answer 1

you could use these methods:

    Files.copy(source, target, options)
    Files.walkFileTree(Path start, Set<FileVisitOption> options, int maxDepth, FileVisitor<? super Path> visitor) throws IOException

Just walk thru the file tree, and in the FileVisitor do the copy.

example how to do that with working code:

change in this first example below one line, add the <Path> type to FileVisitor, like this:

        Files.walkFileTree(source, options, Integer.MAX_VALUE, new FileVisitor<Path>() {....

http://javatutorialhq.com/java/example-source-code/io/nio/folder-copy/

and this: http://www.studytrails.com/java-io/file-listing-directory-walking.jsp

Answer 2

Apache Commons IO can do the trick for you. Have a look at FileUtils .

Example

File srcDir = new File("D:");
File destDir = new File("C:");
FileUtils.copyFolder(srcDir, destDir);

If you need to use java7 or +

public void copy(File source, File target) throws IOException {
    if (source.isDirectory())
        copyFolder(source, target);
    else
        copyFile(source, target);
}

private void copyFolder(File source, File target) throws IOException {
    if (!target.exists())
        target.mkdir();

    for (String f : source.list())
        copy(new File(source, f), new File(target, f));
}

private void copyFile(File source, File target) throws IOException {        
    try (
            InputStream in = new FileInputStream(source);
            OutputStream out = new FileOutputStream(target)
    ) {
        byte[] buf = new byte[1024];
        int length;
        while ((length = in.read(buf)) > 0) {
            out.write(buf, 0, length);
        }
    }
}

Answer 3

(sorry for the self ad...)

If you use Java 7, you can have a go and try one of my projects ; this allows you to do what you want:

final Path src = Paths.get(srcdir);
final Path dst = Paths.get(dstdir);

MoreFiles.copyRecursive(src, dst, RecursionMode.KEEP_GOING);

Note however that it will create the source in the destination; this may not be what you want. But then if you only want to copy the contents you can do that:

if (Files.isRegularFile(src))
    Files.copy(src, dst.resolve(src.getFileName().toString());
else {
    try (
        final Stream<Path> files = Files.list(src);
    ) {
        final List<Path> list = files.collect(Collectors.toList());
        for (final Path entry: list)
            MoreFiles.copyRecursive(entry, dst, RecursionMode.KEEP_GOING);
    }
}

Why I don't use the stream directly in the second example: it's because of the mess of handling checked exceptions in lambdas; but then again, and sorry for the self ad again , you may want to have a look at throwing-lambdas in this case, in which case copying directory entries can be done this way:

final Consumer<Path> copy 
    = Throwing.consumer(entry -> MoreFiles.copyRecursive(entry, dst, RecursionMode.KEEP_GOING);

try (
    final Stream<Path> files = Files.list(src);
) {
    files.forEach(copy);
}