Ant example source code file (KeySubst.java)

This example Ant source code file (KeySubst.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Ant tags/keywords

bufferedreader, bufferedwriter, buildexception, file, hashtable, hashtable, io, ioexception, ioexception, keysubst, string, string, stringbuffer, stringtokenizer, stringtokenizer, util

The KeySubst.java source code

/*
 *  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.
 *
 */

package org.apache.tools.ant.taskdefs;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Hashtable;
import java.util.StringTokenizer;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Task;

/**
 * Keyword substitution. Input file is written to output file.
 * Do not make input file same as output file.
 * Keywords in input files look like this: @foo@. See the docs for the
 * setKeys method to understand how to do the substitutions.
 *
 * @since Ant 1.1
 * @deprecated KeySubst is deprecated since Ant 1.1. Use Filter + Copy
 * instead.
 */
public class KeySubst extends Task {
    private File source = null;
    private File dest = null;
    private String sep = "*";
    private Hashtable replacements = new Hashtable();

    /**
     * Do the execution.
     * @throws BuildException on error
     */
    public void execute() throws BuildException {
        log("!! KeySubst is deprecated. Use Filter + Copy instead. !!");
        log("Performing Substitutions");
        if (source == null || dest == null) {
            log("Source and destinations must not be null");
            return;
        }
        BufferedReader br = null;
        BufferedWriter bw = null;
        try {
            br = new BufferedReader(new FileReader(source));
            dest.delete();
            bw = new BufferedWriter(new FileWriter(dest));

            String line = null;
            String newline = null;
            line = br.readLine();
            while (line != null) {
                if (line.length() == 0) {
                    bw.newLine();
                } else {
                    newline = KeySubst.replace(line, replacements);
                    bw.write(newline);
                    bw.newLine();
                }
                line = br.readLine();
            }
            bw.flush();
        } catch (IOException ioe) {
            ioe.printStackTrace();
        } finally {
            if (bw != null) {
                try {
                    bw.close();
                } catch (IOException e) {
                    // ignore
                }
            }
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    // ignore
                }
            }
        }
    }

    /**
     * Set the source file.
     * @param s the source file
     */
    public void setSrc(File s) {
        this.source = s;
    }

    /**
     * Set the destination file.
     * @param dest the destination file
     */
    public void setDest(File dest) {
        this.dest = dest;
    }

    /**
     * Sets the separator between name=value arguments
     * in setKeys(). By default it is "*".
     * @param sep the separator string
     */
    public void setSep(String sep) {
        this.sep = sep;
    }
    /**
     * Sets the keys.
     *
     * Format string is like this:
     *   <p>
     *   name=value*name2=value
     *   <p>
     *   Names are case sensitive.
     *   <p>
     *   Use the setSep() method to change the * to something else
     *   if you need to use * as a name or value.
     * @param keys a <code>String value
     */
    public void setKeys(String keys) {
        if (keys != null && keys.length() > 0) {
            StringTokenizer tok =
            new StringTokenizer(keys, this.sep, false);
            while (tok.hasMoreTokens()) {
                String token = tok.nextToken().trim();
                StringTokenizer itok =
                new StringTokenizer(token, "=", false);

                String name = itok.nextToken();
                String value = itok.nextToken();
                replacements.put(name, value);
            }
        }
    }


    /**
     * A test method.
     * @param args not used
     */
    public static void main(String[] args) {
        try {
            Hashtable hash = new Hashtable();
            hash.put("VERSION", "1.0.3");
            hash.put("b", "ffff");
            System.out.println(KeySubst.replace("$f ${VERSION} f ${b} jj $",
                                                hash));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Does replacement on text using the hashtable of keys.
     * @param origString an input string
     * @param keys       mapping of keys to values
     * @return the string with the replacements in it.
     * @throws BuildException on error
     */
    public static String replace(String origString, Hashtable keys)
        throws BuildException {
        StringBuffer finalString = new StringBuffer();
        int index = 0;
        int i = 0;
        String key = null;
        while ((index = origString.indexOf("${", i)) > -1) {
            key = origString.substring(index + 2, origString.indexOf("}",
                                       index + 3));
            finalString.append (origString.substring(i, index));
            if (keys.containsKey(key)) {
                finalString.append (keys.get(key));
            } else {
                finalString.append ("${");
                finalString.append (key);
                finalString.append ("}");
            }
            i = index + 3 + key.length();
        }
        finalString.append (origString.substring(i));
        return finalString.toString();
    }
}