source: release-kits/shared/ant-tasks/orans/RegexSearchReplace.java@ 16532

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 !!" );
        }


        //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 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;
        try {
            while ( (line = in.readLine()) != null ) {
                line = line.replaceAll( pattern, replacement);
                out.write(line);
                out.newLine();
            }
        } catch ( Exception e ) {
            throw new BuildException( "Error - Couldn't read from the specified 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" );
        }
        
    }

   
    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( "\\\\", "\\\\\\\\" );
    }


}