mirror of
https://github.com/apache/ant.git
synced 2025-05-19 14:34:45 +00:00
115 lines
4.5 KiB
HTML
115 lines
4.5 KiB
HTML
<!--
|
|
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.
|
|
-->
|
|
<html>
|
|
<head>
|
|
<meta http-equiv="Content-Language" content="en-us">
|
|
<link rel="stylesheet" type="text/css" href="stylesheets/style.css">
|
|
<title>InputHandler</title>
|
|
</head>
|
|
|
|
<body>
|
|
<h1>InputHandler</h1>
|
|
|
|
<h2>Overview</h2>
|
|
|
|
<p>When a task wants to prompt a user for input, it doesn't simply
|
|
read the input from the console as this would make it impossible to
|
|
embed Apache Ant in an IDE. Instead it asks an implementation of the
|
|
<code>org.apache.tools.ant.input.InputHandler</code> interface to
|
|
prompt the user and hand the user input back to the task.</p>
|
|
|
|
<p>To do this, the task creates an <code>InputRequest</code> object
|
|
and passes it to the <code>InputHandler</code>. Such an
|
|
<code>InputRequest</code> may know whether a given user input is valid
|
|
and the <code>InputHandler</code> is supposed to reject all invalid
|
|
input.</p>
|
|
|
|
<p>Exactly one <code>InputHandler</code> instance is associated with
|
|
every Ant process, users can specify the implementation using the
|
|
<code>-inputhandler</code> command line switch.</p>
|
|
|
|
<h2>InputHandler</h2>
|
|
|
|
<p>The <code>InputHandler</code> interface contains exactly one
|
|
method</p>
|
|
|
|
<pre>
|
|
void handleInput(InputRequest request)
|
|
throws org.apache.tools.ant.BuildException;</pre>
|
|
|
|
<p>with some pre- and postconditions. The main postcondition is that
|
|
this method must not return unless the <code>request</code> considers
|
|
the user input valid; it is allowed to throw an exception in this
|
|
situation.</p>
|
|
|
|
<p>Ant comes with three built-in implementations of this interface:</p>
|
|
|
|
<h3 id="defaulthandler">DefaultInputHandler</h3>
|
|
|
|
<p>This is the implementation you get, when you don't use
|
|
the <code>-inputhandler</code> command line switch at all. This
|
|
implementation will print the prompt encapsulated in
|
|
the <code>request</code> object to Ant's logging system and
|
|
re-prompt for input until the user enters something that is considered
|
|
valid input by the <code>request</code> object. Input will be read
|
|
from the console and the user will need to press the Return key.</p>
|
|
|
|
<h3>PropertyFileInputHandler</h3>
|
|
|
|
<p>This implementation is useful if you want to run unattended build
|
|
processes. It reads all input from a properties file and makes the
|
|
build fail if it cannot find valid input in this file. The name of
|
|
the properties file must be specified in the Java system
|
|
property <code>ant.input.properties</code>.</p>
|
|
|
|
<p>The prompt encapsulated in a <code>request</code> will be used as
|
|
the key when looking up the input inside the properties file. If no
|
|
input can be found, the input is considered invalid and an exception
|
|
will be thrown.</p>
|
|
|
|
<p><strong>Note</strong> that <code>ant.input.properties</code> must
|
|
be a Java system property, not an Ant property. I.e. you cannot
|
|
define it as a simple parameter to <code>ant</code>, but you can
|
|
define it inside the <code>ANT_OPTS</code> environment variable.</p>
|
|
|
|
<h3>GreedyInputHandler</h3>
|
|
|
|
<p>Like the default implementation, this InputHandler reads from standard
|
|
input. However, it consumes <em>all</em> available input. This behavior is
|
|
useful for sending Ant input via an OS pipe. <em>Since Ant 1.7</em></p>
|
|
|
|
<h3>SecureInputHandler</h3>
|
|
|
|
<p>This InputHandler calls <code>System.console().readPassword()</code>,
|
|
available since Java 6. On earlier platforms it falls back to the
|
|
behavior of DefaultInputHandler. <em>Since Ant 1.7.1</em></p>
|
|
|
|
<h2>InputRequest</h2>
|
|
|
|
<p>Instances of <code>org.apache.tools.ant.input.InputRequest</code>
|
|
encapsulate the information necessary to ask a user for input and
|
|
validate this input.</p>
|
|
|
|
<p>The instances of <code>InputRequest</code> itself will accept any
|
|
input, but subclasses may use stricter
|
|
validations. <code>org.apache.tools.ant.input.MultipleChoiceInputRequest</code>
|
|
should be used if the user input must be part of a predefined set of
|
|
choices.</p>
|
|
|
|
</body>
|
|
</html>
|