Regular Expression Regex-2 (Java)

又用Java實現了一個，發現Java的Regex略有不同，而且也感覺到了Java的讀寫檔案很不雅觀。

/*
* Created on 2004-10-1
*/
import java.util.regex.*;
import java.io.*;

/**
* @author dancefire
*/
public class DataFilter {

    public static void main(String[] args) {
        if(args.length < 2)
        {
            System.err.println("Please enter 2 filenames(e.g. In.txt Out.txt)");
            return;
        }
        String strIn = null, strOut = null;
        
        //    Get string from a file
        strIn = readFile(args[0]);
        //    Process
        strOut = filter(strIn);
        //    Store Result into a file
        writeFile(args[1], strOut);
        
    }
    private static void writeFile(String filename, String data)
    {
        BufferedWriter wr = null;
        try{
            wr = new BufferedWriter( new FileWriter(filename));
            wr.write(data);
        }catch( Exception e )
        {
            e.printStackTrace();
        }finally{
            try{
                if( wr != null )
                    wr.close();
            }catch( Exception e ){
                e.printStackTrace();
            }
        }
        return;
    }
    private static String readFile(String filename)
    {
        String strRet = null;
        BufferedReader rd = null;
        try{
            rd = new BufferedReader( new FileReader(filename));
            String line = null;
            StringBuffer sb = new StringBuffer();
            while( (line=rd.readLine()) != null )
            {
                sb.append(line);
            }
            strRet = sb.toString();            
        }catch( Exception e )
        {
            e.printStackTrace();
        }finally{
            try{
                if( rd != null )
                    rd.close();
            }catch( Exception e ){
                e.printStackTrace();
            }
        }
        return strRet;
    }
    private static String filter(String input)
    {
        Pattern p = Pattern.compile("/"(//w+):(//w+)%(//w+)/"");
        Matcher m = p.matcher(input);
        StringBuffer sb = new StringBuffer();
        while(m.find())
        {
            sb.append( m.group(1) + ":" + m.group(2) + "*" + m.group(3) + "," + System.getProperty("line.separator") );
        }
        return sb.toString();
    }
}