examplefilefilter.java

接上一个程序 播放器可以实现波形的显示 还可以改变采样点个数和算法

import java.io.File;
import java.util.Hashtable;
import java.util.Enumeration;
import javax.swing.*;
import javax.swing.filechooser.*;

public class ExampleFileFilter extends FileFilter 
{
    private static String TYPE_UNKNOWN = "Type Unknown";
    private static String HIDDEN_FILE = "Hidden File";

    private Hashtable filters = null;
    private String description = null;
    private String fullDescription = null;
    private boolean useExtensionsInDescription = true;

    public ExampleFileFilter() 
    {
		this.filters = new Hashtable();
    }

    public ExampleFileFilter(String extension) 
    {
		this(extension,null);
    }


    public ExampleFileFilter(String extension, String description) 
    {
		this();
		if(extension!=null) addExtension(extension);
 		if(description!=null) setDescription(description);
    }


    public ExampleFileFilter(String[] filters) 
    {
		this(filters, null);
    }


    public ExampleFileFilter(String[] filters, String description) 
    {
		this();
		for (int i = 0; i < filters.length; i++) 
		{		
	    	// add filters one by one
	    	addExtension(filters[i]);
		}
 		if(description!=null) setDescription(description);
    }


    public boolean accept(File f) 
    {
	    
		if(f != null) 
		{
		    if(f.isDirectory()) 
		    {
				return true;
		    }
		    
		    String extension = getExtension(f);
		    
		    if(extension != null && filters.get(getExtension(f)) != null) 
		    {
				return true;
		    };
		}
		return false;
    }


    public String getExtension(File f) 
    {
		if(f != null) 
		{
		    String filename = f.getName();
		    int i = filename.lastIndexOf('.');
		    if(i>0 && i<filename.length()-1) 
		    {
				return filename.substring(i+1).toLowerCase();
		    };
		}
		return null;
    }


    public void addExtension(String extension) 
    {
		if(filters == null) 
	{
	    filters = new Hashtable(5);
	}
		filters.put(extension.toLowerCase(), this);
		fullDescription = null;
    }


    public String getDescription() 
    {
		if(fullDescription == null) 
		{
	    	if(description == null || isExtensionListInDescription()) 
	   		{
 				fullDescription = description==null ? "(" : description + " (";
				// build the description from the extension list
				Enumeration extensions = filters.keys();
				if(extensions != null) 
				{
		    		fullDescription += "." + (String) extensions.nextElement();
		    		while (extensions.hasMoreElements()) 
		    		{
						fullDescription += ", ." + (String) extensions.nextElement();
		    		}
				}
				fullDescription += ")";
	    	} 
	    	else 
	    	{
				fullDescription = description;
	    	}
		}
		
		return fullDescription;
    }

    public void setDescription(String description) 
    {
		this.description = description;
		fullDescription = null;
    }


    public void setExtensionListInDescription(boolean b) 
    {
		useExtensionsInDescription = b;
		fullDescription = null;
    }


    public boolean isExtensionListInDescription() 
    {
		return useExtensionsInDescription;
    }
}