Java/File Input Output/FilenameFilter
Содержание
- 1 Accepts a selection if it is acceptable to both of two FilenameFilters
- 2 A simple file filter for a particular file extension
- 3 Inverted File Filter
- 4 only display files that use the .html extension.
- 5 Removes the file extension from the given file name.
- 6 Returns the file extension of the given file name. The returned value will contain the dot.
- 7 This filter accepts Files that are directories
Accepts a selection if it is acceptable to both of two FilenameFilters
<source lang="java">
import java.io.File; import java.io.FilenameFilter; /**
* Accepts a selection if it is acceptable to both of two {@link FilenameFilter}s.
* This takes two {@link FilenameFilter}s as input.
*
* Eg., to print all files beginning with A and ending with .java:
**
* File dir = new File(".");
* String[] files = dir.list( new AndFileFilter(
* new PrefixFileFilter("A"),
* new ExtensionFileFilter(".java")
* )
* );
* for ( int i=0; i<files.length; i++ )
* {
* System.out.println(files[i]);
* }
*
* * @author * @version $Revision: 494012 $ $Date: 2007-01-08 11:23:58 +0100 (Mo, 08 Jan 2007) $ * @since 4.0 */
public class AndFileFilter
implements FilenameFilter
{
private final FilenameFilter m_filter1;
private final FilenameFilter m_filter2;
public AndFileFilter( final FilenameFilter filter1, final FilenameFilter filter2 )
{
m_filter1 = filter1;
m_filter2 = filter2;
}
public boolean accept( final File file, final String name )
{
return m_filter1.accept( file, name ) && m_filter2.accept( file, name );
}
}
</source>
A simple file filter for a particular file extension
<source lang="java">
//revised from prefuse import java.io.File; import java.util.ArrayList; import java.util.Iterator; import javax.swing.filechooser.FileFilter; /**
* A simple file filter for a particular file extension. * * @author */
public class SimpleFileFilter extends FileFilter {
private ArrayList exts = new ArrayList();
private String desc;
private Object data;
/**
* Create a new SimpleFileFilter.
* @param ext the file extension
* @param desc a description of the file type
*/
public SimpleFileFilter(String ext, String desc) {
addExtension(ext);
this.desc = desc;
}
/**
* Create a new SimpleFileFilter.
* @param ext the file extension
* @param desc a description of the file type
* @param data user-provided attached object
*/
public SimpleFileFilter(String ext, String desc, Object data) {
addExtension(ext);
this.desc = desc;
this.data = data;
}
/**
* Add a file extension to this file filter.
* @param ext the file extension to add
*/
public void addExtension(String ext) {
exts.add(ext.toLowerCase());
}
/**
* @see javax.swing.filechooser.FileFilter#accept(java.io.File)
*/
public boolean accept(File f) {
if ( f == null )
return false;
if ( f.isDirectory() )
return true;
String extension = getExtension(f);
if ( extension == null ) return false;
for ( Iterator iter = exts.iterator(); iter.hasNext(); ) {
String ext = (String)iter.next();
if ( ext.equalsIgnoreCase(extension) )
return true;
}
return false;
}
/**
* Returns the extension for a file or null if there is none
* @param f the input file
* @return the file extension, or null if none
*/
public static String getExtension(File f) {
return (f != null ? getExtension(f.getName()) : null);
}
/**
* Returns the extension for a file or null if there is none
* @param filename the input filename
* @return the file extension, or null if none
*/
public static String getExtension(String filename) {
int i = filename.lastIndexOf(".");
if ( i>0 && i<filename.length()-1 ) {
return filename.substring(i+1).toLowerCase();
} else {
return null;
}
}
/**
* Get a user-provided attached object.
* @return the user-provided attached object
*/
public Object getUserData() {
return data;
}
/**
* @see javax.swing.filechooser.FileFilter#getDescription()
*/
public String getDescription() {
return desc;
}
/**
* Get the first file extension associated with this filter.
* @return the first file extension associated with this filter
*/
public String getExtension() {
return (String)exts.get(0);
}
} // end of class SimpleFileFilter
</source>
Inverted File Filter
<source lang="java">
/****************************************************************
* Licensed to the Apache Software Foundation (ASF) under one * * or more contributor license agreements. See the NOTICE file * * distributed with this work for additional information * * regarding copyright ownership. The ASF licenses this file * * to you under the Apache License, Version 2.0 (the * * "License"); you may not use this file except in compliance * * with the License. You may obtain a copy of the License at * * * * http://www.apache.org/licenses/LICENSE-2.0 * * * * Unless required by applicable law or agreed to in writing, * * software distributed under the License is distributed on an * * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * * KIND, either express or implied. See the License for the * * specific language governing permissions and limitations * * under the License. * ****************************************************************/
import java.io.File; import java.io.FilenameFilter; /**
* This takes a FilenameFilter<code> as input and inverts the selection.
* This is used in retrieving files that are not accepted by a filter.
*
* @author
* @version CVS $Revision: 494012 $ $Date: 2007-01-08 11:23:58 +0100 (Mo, 08 Jan 2007) $
* @since 4.0
*/
public class InvertedFileFilter
implements FilenameFilter
{
private final FilenameFilter m_originalFilter;
public InvertedFileFilter( final FilenameFilter originalFilter )
{
m_originalFilter = originalFilter;
}
public boolean accept( final File file, final String name )
{
return !m_originalFilter.accept( file, name );
}
}
</source>
only display files that use the .html extension.
<source lang="java">
import java.io.File; import java.io.FilenameFilter; class DirListOnly {
public static void main(String args[]) {
String dirname = "/java";
File f1 = new File(dirname);
FilenameFilter only = new OnlyExt("html");
String s[] = f1.list(only);
for (int i = 0; i < s.length; i++) {
System.out.println(s[i]);
}
}
} class OnlyExt implements FilenameFilter {
String ext;
public OnlyExt(String ext) {
this.ext = "." + ext;
}
public boolean accept(File dir, String name) {
return name.endsWith(ext);
}
}
</source>
Removes the file extension from the given file name.
<source lang="java">
import java.net.URL; /*
* JCommon : a free general purpose class library for the Java(tm) platform * * * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors. * * Project Info: http://www.jfree.org/jcommon/index.html * * This library is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation; either version 2.1 of the License, or * (at your option) any later version. * * This library is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public * License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, * USA. * * [Java is a trademark or registered trademark of Sun Microsystems, Inc. * in the United States and other countries.] * * ------------ * IOUtils.java * ------------ * (C)opyright 2002-2004, by Thomas Morgner and Contributors. * * Original Author: Thomas Morgner; * Contributor(s): David Gilbert (for Object Refinery Limited); * * $Id: IOUtils.java,v 1.8 2009/01/22 08:34:58 taqua Exp $ * * Changes * ------- * 26-Jan-2003 : Initial version * 23-Feb-2003 : Documentation * 25-Feb-2003 : Fixed Checkstyle issues (DG); * 29-Apr-2003 : Moved to jcommon * 04-Jan-2004 : Fixed JDK 1.2.2 issues with createRelativeURL; * added support for query strings within these urls (TM); */
/**
* The IOUtils provide some IO related helper methods. * * @author Thomas Morgner. */
public class Main {
/**
* Removes the file extension from the given file name.
*
* @param file the file name.
* @return the file name without the file extension.
*/
public String stripFileExtension(final String file) {
final int idx = file.lastIndexOf(".");
// handles unix hidden files and files without an extension.
if (idx < 1) {
return file;
}
return file.substring(0, idx);
}
}
</source>
Returns the file extension of the given file name. The returned value will contain the dot.
<source lang="java">
import java.net.URL; /*
* JCommon : a free general purpose class library for the Java(tm) platform * * * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors. * * Project Info: http://www.jfree.org/jcommon/index.html * * This library is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation; either version 2.1 of the License, or * (at your option) any later version. * * This library is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public * License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, * USA. * * [Java is a trademark or registered trademark of Sun Microsystems, Inc. * in the United States and other countries.] * * ------------ * IOUtils.java * ------------ * (C)opyright 2002-2004, by Thomas Morgner and Contributors. * * Original Author: Thomas Morgner; * Contributor(s): David Gilbert (for Object Refinery Limited); * * $Id: IOUtils.java,v 1.8 2009/01/22 08:34:58 taqua Exp $ * * Changes * ------- * 26-Jan-2003 : Initial version * 23-Feb-2003 : Documentation * 25-Feb-2003 : Fixed Checkstyle issues (DG); * 29-Apr-2003 : Moved to jcommon * 04-Jan-2004 : Fixed JDK 1.2.2 issues with createRelativeURL; * added support for query strings within these urls (TM); */
/**
* The IOUtils provide some IO related helper methods. * * @author Thomas Morgner. */
public class Main {
/**
* Returns the file extension of the given file name.
* The returned value will contain the dot.
*
* @param file the file name.
* @return the file extension.
*/
public String getFileExtension(final String file) {
final int idx = file.lastIndexOf(".");
// handles unix hidden files and files without an extension.
if (idx < 1) {
return "";
}
return file.substring(idx);
}
}
</source>
This filter accepts Files that are directories
<source lang="java">
/****************************************************************
* Licensed to the Apache Software Foundation (ASF) under one * * or more contributor license agreements. See the NOTICE file * * distributed with this work for additional information * * regarding copyright ownership. The ASF licenses this file * * to you under the Apache License, Version 2.0 (the * * "License"); you may not use this file except in compliance * * with the License. You may obtain a copy of the License at * * * * http://www.apache.org/licenses/LICENSE-2.0 * * * * Unless required by applicable law or agreed to in writing, * * software distributed under the License is distributed on an * * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * * KIND, either express or implied. See the License for the * * specific language governing permissions and limitations * * under the License. * ****************************************************************/
import java.io.File; import java.io.FilenameFilter; /**
* This filter accepts <code>Files that are directories.*
Eg., here is how to print out a list of the current directory"s subdirectories:
**
* File dir = new File(".");
* String[] files = dir.list( new DirectoryFileFilter() );
* for ( int i=0; i<files.length; i++ )
* {
* System.out.println(files[i]);
* }
*
* * @author * @version $Revision: 494012 $ $Date: 2007-01-08 11:23:58 +0100 (Mo, 08 Jan 2007) $ * @since 4.0 */
public class DirectoryFileFilter
implements FilenameFilter
{
public boolean accept( final File file, final String name )
{
return new File( file, name ).isDirectory();
}
}
</source>
