source: release-kits/shared/ant-tasks/orans/RegexSearchReplace.java@ 16535

import org.apache.tools.ant.*;
import org.apache.tools.ant.taskdefs.*;
import java.util.*;
import java.io.*;
import java.util.regex.*;


public class RegexSearchReplace extends Task {
    private File file = null;
    private String pattern = null;
    private String replacement = null;
    

    /**
     * for testing
     */
    public static void main( String[] args ) {

        RegexSearchReplace rsr = new RegexSearchReplace();
        rsr.setFile(new File (args[0]));
        rsr.setPattern(args[1]);
        rsr.setReplacement(args[2]);

        rsr.execute();

    }

    public void execute() {

        if ( file == null ) {
            throw new BuildException( "Error - No file specified !!" );
        }

        if ( pattern == null ) {
            throw new BuildException( "Error - No pattern specified !!" );
        }

        if (replacement == null) {
            throw new BuildException( "Error - No replacement specified !!" );
        }

        System.out.println( "File: " + file );
        System.out.println( "Pattern: " + pattern );
        System.out.println( "Replacement: " + replacement );

        int noReplaces = 0;

        //create the output stream
        BufferedWriter out = null;
        File temp = null;
        try {
            //create temp file.
            temp = File.createTempFile("rsr", ".tmp");

            //delete temp file when program exits.
            temp.deleteOnExit();

            //writer to temp file
            out = new BufferedWriter(new FileWriter(temp));

        } catch (IOException e) {
            throw new BuildException( "Error - Couldn't create or open the temp file" );
        }


        //create the input stream
        BufferedReader in = null;
        try {
            in = new BufferedReader( new FileReader( file ) );
        } catch ( Exception e ) {
            throw new BuildException( "Error - Couldn't open the specified file" );
        }

        //pass the file through, searching and replacing
        String line;
        boolean hasMoreLines = true;
        while ( hasMoreLines ) {

            try {
                line = in.readLine();
            } catch ( Exception e ) {
                throw new BuildException( "Error - Couldn't read from the specified file" );
            }

            if ( line == null ) {
                hasMoreLines = false;
            } else {

                String oldLine = line;
                line = line.replaceAll(pattern, replacement);
                if ( !oldLine.equals( line ) ) {
                    noReplaces++;
                }

                try {
                    out.write(line);
                    out.newLine();
                } catch ( Exception e ) {
                    throw new BuildException( "Error - Couldn't write to the temp file" );
                }
            }
        }
            

        try {
            //close them both up
            in.close();
            out.close();
        } catch ( Exception e ) {
            throw new BuildException( "Error - Couldn't close a file" );
        }


        //copy the new file (temp) over the original
        InputStream i;
        OutputStream o;
        try {
            i = new FileInputStream(temp);
            o = new FileOutputStream(file);

        } catch ( Exception e ) {
            throw new BuildException( "Error - Couldn't open the temp file" );
        }

        try {
    
            // Transfer bytes from in to out
            byte[] buf = new byte[1024];
            int len;
            while ((len = i.read(buf)) > 0) {
               o.write(buf, 0, len);
            }

            //close them up
            i.close();
            o.close();
        } catch ( Exception e ) {
            throw new BuildException( "Error - Couldn't write to the specified file" );
        }

        String linesWord = "lines";     
        if ( noReplaces == 1 ) {
            linesWord = "line";
        }
        System.out.println( "Successfully changed " + noReplaces + " " + linesWord );
    }

   
    public void setFile(File file) {
            this.file = file;
    }

    public void setPattern(String pattern) {
            this.pattern = pattern;
    }

    public void setReplacement(String replacement) {
            this.replacement = replacement.replaceAll( "\\\\", "\\\\\\\\" );
    }


}