| 1 | <!--
|
|---|
| 2 | Licensed to the Apache Software Foundation (ASF) under one or more
|
|---|
| 3 | contributor license agreements. See the NOTICE file distributed with
|
|---|
| 4 | this work for additional information regarding copyright ownership.
|
|---|
| 5 | The ASF licenses this file to You under the Apache License, Version 2.0
|
|---|
| 6 | (the "License"); you may not use this file except in compliance with
|
|---|
| 7 | the License. You may obtain a copy of the License at
|
|---|
| 8 |
|
|---|
| 9 | http://www.apache.org/licenses/LICENSE-2.0
|
|---|
| 10 |
|
|---|
| 11 | Unless required by applicable law or agreed to in writing, software
|
|---|
| 12 | distributed under the License is distributed on an "AS IS" BASIS,
|
|---|
| 13 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|---|
| 14 | See the License for the specific language governing permissions and
|
|---|
| 15 | limitations under the License.
|
|---|
| 16 | -->
|
|---|
| 17 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
|
|---|
| 18 | <html>
|
|---|
| 19 | <head>
|
|---|
| 20 | <meta http-equiv="Content-Language" content="en-us">
|
|---|
| 21 | <link rel="stylesheet" type="text/css" href="stylesheets/style.css">
|
|---|
| 22 | <title>InputHandler</title>
|
|---|
| 23 | </head>
|
|---|
| 24 |
|
|---|
| 25 | <body>
|
|---|
| 26 | <h1>Using Ant Tasks Outside of Ant</h1>
|
|---|
| 27 |
|
|---|
| 28 | <h2>Rationale</h2>
|
|---|
| 29 |
|
|---|
| 30 | <p>Ant provides a rich set of tasks for buildfile creators and
|
|---|
| 31 | administrators. But what about programmers? Can the functionality
|
|---|
| 32 | provided by Ant tasks be used in java programs?</p>
|
|---|
| 33 |
|
|---|
| 34 | <p>Yes, and its quite easy. Before getting into the details, however,
|
|---|
| 35 | we should mention the pros and cons of this approach:
|
|---|
| 36 |
|
|---|
| 37 | <h3>Pros</h3>
|
|---|
| 38 |
|
|---|
| 39 | <table cellpadding="0" margin="0" border="1">
|
|---|
| 40 | <tr>
|
|---|
| 41 | <td><b>Robust</b></td>
|
|---|
| 42 | <td>
|
|---|
| 43 | Ant tasks are very robust. They have been banged on by many people.
|
|---|
| 44 | Ant tasks have been used in many different contexts, and have
|
|---|
| 45 | therefore been instrumented to take care of a great many boundary
|
|---|
| 46 | conditions and potentially obscure errors.
|
|---|
| 47 | </td>
|
|---|
| 48 | </tr>
|
|---|
| 49 | <tr>
|
|---|
| 50 | <td><b>Cross Platform</b></td>
|
|---|
| 51 | <td>
|
|---|
| 52 | Ant tasks are cross platform. They have been tested on all of the
|
|---|
| 53 | volume platforms, and several rather unusual ones (Netware and OS/390, to
|
|---|
| 54 | name a few).
|
|---|
| 55 | </td>
|
|---|
| 56 | </tr>
|
|---|
| 57 | <tr>
|
|---|
| 58 | <td><b>Community Support</b></td>
|
|---|
| 59 | <td>
|
|---|
| 60 | Using Ant tasks means you have less of your own code to support. Ant
|
|---|
| 61 | code is supported by the entire Apache Ant community.
|
|---|
| 62 | </td>
|
|---|
| 63 | </tr>
|
|---|
| 64 | </table>
|
|---|
| 65 |
|
|---|
| 66 | <h3>Cons</h3>
|
|---|
| 67 |
|
|---|
| 68 | <table cellpadding="0" margin="0" border="1">
|
|---|
| 69 | <tr>
|
|---|
| 70 | <td><b>Dependency on Ant Libraries</b></td>
|
|---|
| 71 | <td>
|
|---|
| 72 | Obviously, if you use an Ant task in your code, you will have to add
|
|---|
| 73 | "ant.jar" to your path. Of course, you could use a code optimizer to
|
|---|
| 74 | remove the unnecessary classes, but you will still probably require a
|
|---|
| 75 | chunk of the Ant core.
|
|---|
| 76 | </td>
|
|---|
| 77 | </tr>
|
|---|
| 78 | <tr>
|
|---|
| 79 | <td><b>Loss of Flexibility</b></td>
|
|---|
| 80 | <td>
|
|---|
| 81 | At some point, if you find yourself having to modify the Ant code, it
|
|---|
| 82 | probably makes more sense to "roll your own." Of course, you can
|
|---|
| 83 | still steal some code snippets and good ideas. This is the beauty of
|
|---|
| 84 | open source!
|
|---|
| 85 | </td>
|
|---|
| 86 | </tr>
|
|---|
| 87 | </table>
|
|---|
| 88 |
|
|---|
| 89 |
|
|---|
| 90 | <h2>Example</h2>
|
|---|
| 91 |
|
|---|
| 92 | <p>Let's say you want to unzip a zip file programmatically from java
|
|---|
| 93 | into a certain directory. Of course you could write your own routine
|
|---|
| 94 | to do this, but why not use the Ant task that has already been written?</p>
|
|---|
| 95 |
|
|---|
| 96 | <p>In my example, I wanted to be able to unzip a file from within an
|
|---|
| 97 | XSLT Transformation. XSLT Transformers can be extended by plugging in
|
|---|
| 98 | static methods in java. I therefore need a function something like
|
|---|
| 99 | this:</p>
|
|---|
| 100 |
|
|---|
| 101 | <pre>
|
|---|
| 102 | /**
|
|---|
| 103 | * Unzip a zip file into a given directory.
|
|---|
| 104 | *
|
|---|
| 105 | * @param zipFilepath A pathname representing a local zip file
|
|---|
| 106 | * @param destinationDir where to unzip the archive to
|
|---|
| 107 | */
|
|---|
| 108 | static public void unzip(String zipFilepath, String destinationDir)
|
|---|
| 109 | </pre>
|
|---|
| 110 |
|
|---|
| 111 | <p>
|
|---|
| 112 | The Ant task to perform this function is
|
|---|
| 113 | <code>org.apache.tools.ant.taskdefs.Expand</code>. All we have to do
|
|---|
| 114 | is create a dummy Ant <code>Project</code> and <code>Target</code>,
|
|---|
| 115 | set the <code>Task</code> parameters that would normally be set in a
|
|---|
| 116 | buildfile, and call <code>execute()</code>.</p>
|
|---|
| 117 |
|
|---|
| 118 | <p>First, let's make sure we have the proper includes:</p>
|
|---|
| 119 |
|
|---|
| 120 | <pre>
|
|---|
| 121 | import org.apache.tools.ant.Project;
|
|---|
| 122 | import org.apache.tools.ant.Target;
|
|---|
| 123 | import org.apache.tools.ant.taskdefs.Expand;
|
|---|
| 124 | import java.io.File;
|
|---|
| 125 | </pre>
|
|---|
| 126 |
|
|---|
| 127 | <p>The function call is actually quite simple:</p>
|
|---|
| 128 |
|
|---|
| 129 | <pre>
|
|---|
| 130 | static public void unzip(String zipFilepath, String destinationDir) {
|
|---|
| 131 |
|
|---|
| 132 | final class Expander extends Expand {
|
|---|
| 133 | public Expander() {
|
|---|
| 134 | project = new Project();
|
|---|
| 135 | project.init();
|
|---|
| 136 | taskType = "unzip";
|
|---|
| 137 | taskName = "unzip";
|
|---|
| 138 | target = new Target();
|
|---|
| 139 | }
|
|---|
| 140 | }
|
|---|
| 141 | Expander expander = new Expander();
|
|---|
| 142 | expander.setSrc(new File(zipfile));
|
|---|
| 143 | expander.setDest(new File(destdir));
|
|---|
| 144 | expander.execute();
|
|---|
| 145 | </pre>
|
|---|
| 146 |
|
|---|
| 147 | <p>In actual practice, you will probably want to add your own error
|
|---|
| 148 | handling code and you may not want to use a local inner class.
|
|---|
| 149 | However, the point of the example is to show how an Ant task can be
|
|---|
| 150 | called programmatically in relatively few lines of code.</p>
|
|---|
| 151 |
|
|---|
| 152 | <p>The question you are probably asking yourself at this point is:
|
|---|
| 153 | <i>How would I know which classes and methods have to be called in
|
|---|
| 154 | order to set up a dummy Project and Target?</i> The answer is: you
|
|---|
| 155 | don't. Ultimately, you have to be willing to get your feet wet and
|
|---|
| 156 | read the source code. The above example is merely designed to whet
|
|---|
| 157 | your appetite and get you started. Go for it!</p>
|
|---|
| 158 |
|
|---|
| 159 |
|
|---|
| 160 | </html>
|
|---|
