Selectors are a mechanism whereby the files that make up a fileset
can be selected based on criteria other than filename as provided
by the <include>
and <exclude>
tags.
A selector is an element of FileSet, and appears within it. It can also be defined outside of any target by using the <selector> tag and then using it as a reference.
Different selectors have different attributes. Some selectors can
contain other selectors, and these are called
Selector Containers
.
There is also a category of selectors that allow
user-defined extensions, called
Custom Selectors
.
The ones built in to Ant are called
Core Selectors
.
Core selectors are the ones that come standard with Ant. They can be used within a fileset and can be contained within Selector Containers.
The core selectors are:
The <contains>
tag in a FileSet limits
the files defined by that fileset to only those which contain the
string specified by the text
attribute.
.
Attribute | Description | Required |
text | Specifies the text that every file must contain | Yes |
casesensitive | Whether to pay attention to case when looking
for the string in the text attribute. Default is
true.
|
No |
Here is an example of how to use the Contains Selector:
<fileset dir="${doc.path}" includes="**/*.html"> <contains text="script" casesensitive="no"/> </fileset>
Selects all the HTML files that contain the string
script
.
The <date>
tag in a FileSet will put
a limit on the files specified by the include tag, so that tags
whose last modified date does not meet the date limits specified
by the selector will not end up being selected.
Attribute | Description | Required |
datetime | Specifies the date and time to test for using a string of the format MM/DD/YYYY HH:MM AM_or_PM. | At least one of the two. |
millis | The number of milliseconds since 1970 that should be tested for. It is usually much easier to use the datetime attribute. | |
granularity | The number of milliseconds leeway to give before deciding whether a files modification time matches a date. This is needed because not every file system supports tracking the last modified time to the millisecond level. The file will be selected provided the condition could be true were the granularity added or subtracted from the actual time. Default is 0 milliseconds except on Windows systems, where it is 2000 milliseconds (2 seconds). | No |
when | Indicates how to interpret the date, whether
the files to be selected are those whose last modified times should
be before, after, or equal to the specified value. Acceptable
values for this attribute are:
| No |
Here is an example of how to use the Date Selector:
<fileset dir="${jar.path}" includes="**/*.jar"> <date datetime="01/01/2001 12:00 AM" when="before"/> </fileset>
Selects all JAR files which were last modified before midnight January 1, 2001.
The <depend>
tag selects files
whose last modified date is later than another, equivalent file in
another location.
The <depend>
tag supports the use of a
contained <mapper>
element
to define the location of the file to be compared against. If no
<mapper>
element is specified, the
identity
type mapper is used.
Attribute | Description | Required |
targetdir | The base directory to look for the files to compare
against. The precise location depends on a combination of this
attribute and the <mapper> element, if any.
|
Yes |
granularity | The number of milliseconds leeway to give before deciding a file is out of date. This is needed because not every file system supports tracking the last modified time to the millisecond level. Default is 0 milliseconds except on Windows systems, where it is 2000 milliseconds (2 seconds). | No |
Here is an example of how to use the Depend Selector:
<fileset dir="${ant.1.5}/src/main" includes="**/*.java"> <depend targetdir="${ant.1.4.1}/src/main"/> </fileset>
Selects all the Java source files which were modified in the 1.5 release.
The <depth>
tag selects files based on
how many directy levels deep they are in relation to the base
directory of the fileset.
Attribute | Description | Required |
min | The minimum number of directory levels below the base directory that a file must be in order to be selected. Default is no limit. | At least one of the two. |
max | The maximum number of directory levels below the base directory that a file can be and still be selected. Default is no limit. |
Here is an example of how to use the Depth Selector:
<fileset dir="${doc.path}" includes="**/*"> <depth max="1"/> </fileset>
Selects all files in the base directory and one directory below that.
The <filename>
tag acts like the
<include>
and <exclude>
tags within a fileset. By using a selector instead, however,
one can combine it with all the other selectors using whatever
selector container is desired.
Attribute | Description | Required |
name | The name of files to select. The name parameter can contain the standard Ant wildcard characters. | Yes |
casesensitive | Whether to pay attention to case when looking at file names. Default is "true". | No |
negate | Whether to reverse the effects of this filename selection, therefore emulating an exclude rather than include tag. Default is "false". | No |
Here is an example of how to use the Filename Selector:
<fileset dir="${doc.path}" includes="**/*"> <filename name="**/*.css"/> </fileset>
Selects all the cascading style sheet files.
The <present>
tag selects files
that have an equivalent file in another directory tree.
The <present>
tag supports the use of a
contained <mapper>
element
to define the location of the file to be tested against. If no
<mapper>
element is specified, the
identity
type mapper is used.
Attribute | Description | Required |
targetdir | The base directory to look for the files to compare
against. The precise location depends on a combination of this
attribute and the <mapper> element, if any.
|
Yes |
present | Whether we are requiring that a file is present in
the src directory tree only, or in both the src and the target
directory tree. Valid values are:
|
No |
Here is an example of how to use the Present Selector:
<fileset dir="${ant.1.5}/src/main" includes="**/*.java"> <present present="srconly" targetdir="${ant.1.4.1}/src/main"/> </fileset>
Selects all the Java source files which are new in the 1.5 release.
The <size>
tag in a FileSet will put
a limit on the files specified by the include tag, so that tags
which do not meet the size limits specified by the selector will not
end up being selected.
Attribute | Description | Required |
value | The size of the file which should be tested for. | Yes |
units | The units that the value attribute
is expressed in. When using the standard single letter SI
designations, such as "k","M", or
"G", multiples of 1000 are used. If you want to use
power of 2 units, use the IEC standard: "Ki" for 1024,
"Mi" for 1048576, and so on. The default is no units,
which means the value attribute expresses the exact
number of bytes.
|
No |
when | Indicates how to interpret the size, whether
the files to be selected should be larger, smaller, or equal to
that value. Acceptable values for this attribute are:
| No |
Here is an example of how to use the Size Selector:
<fileset dir="${jar.path}"> <patternset> <include name="**/*.jar"/> </patternset> <size value="4" units="Ki" when="more"/> </fileset>
Selects all JAR files that are larger than 4096 bytes.
To create more complex selections, a variety of selectors that contain other selectors are available for your use. They combine the selections of their child selectors in various ways.
The selector containers are:
<project>
.
All selector containers can contain any other selector, including other containers, as an element. Using containers, the selector tags can be arbitrarily deep. Here is a complete list of allowable selector elements within a container:
The <and>
tag selects files that are
selected by all of the elements it contains. It returns as
soon as it finds a selector that does not select the file,
so it is not guaranteed to check every selector.
Here is an example of how to use the And Selector:
<fileset dir="${dist}" includes="**/*.jar"> <and> <size value="4" units="Ki" when="more"/> <date datetime="01/01/2001 12:00 AM" when="before"/> </and> </fileset>
Selects all the JAR file larger than 4096 bytes which haven't been update since the last millenium.
The <majority>
tag selects files provided
that a majority of the contained elements also select it. Ties are
dealt with as specified by the allowtie
attribute.
Attribute | Description | Required |
allowtie | Whether files should be selected if there are an even number of selectors selecting them as are not selecting them. Default is true. | No |
Here is an example of how to use the Majority Selector:
<fileset dir="${docs}" includes="**/*.html"> <majority> <contains text="project" casesensitive="false"/> <contains text="taskdef" casesensitive="false"/> <contains text="IntrospectionHelper" casesensitive="true"/> </majority> </fileset>
Selects all the HTML files which contain at least two of the three phrases "project", "taskdef", and "IntrospectionHelper" (this last phrase must match case exactly).
The <none>
tag selects files that are
not selected by any of the elements it contains. It returns as
soon as it finds a selector that selects the file,
so it is not guaranteed to check every selector.
Here is an example of how to use the None Selector:
<fileset dir="${src}" includes="**/*.java"> <none> <present targetdir="${dest}"/> <present targetdir="${dest}"> <mapper type="glob" from="*.java" to="*.class"/> </present> </none> </fileset>
Selects only Java files which do not have equivalent java or class files in the dest directory.
The <not>
tag reverses the meaning of the
single selector it contains.
Here is an example of how to use the Not Selector:
<fileset dir="${src}" includes="**/*.java"> <not> <contains text="test"/> </not> </fileset>
Selects all the files in the src directory that do not contain the string "test".
The <or>
tag selects files that are
selected by any one of the elements it contains. It returns as
soon as it finds a selector that selects the file,
so it is not guaranteed to check every selector.
Here is an example of how to use the Or Selector:
<fileset dir="${basedir}"> <or> <depth max="0"/> <filename name="*.png"/> <filename name="*.gif"/> <filename name="*.jpg"/> </or> </fileset>
Selects all the files in the top directory along with all the image files below it.
The <selector>
tag is used to create selectors
that can be reused through references. It is the only selector which can
be used outside of
any target, as an element of the <project>
tag. It
can contain only one other selector, but of course that selector can
be a container.
Here is an example of how to use the Selector Reference:
<project default="all" basedir="./jakarta-ant"> <selector id="completed"> <none> <depend targetdir="build/classes"> <mapper type="glob" from="*.java" to="*.class"/> </depend> <depend targetdir="docs/manual/api"> <mapper type="glob" from="*.java" to="*.html"/> </depend> </none> </selector> <target> <zip> <fileset dir="src/main" includes="**/*.java"> <selector refid="completed"/> </fileset> </zip> </target> </project>
Zips up all the Java files which have an up-to-date equivalent class file and javadoc file associated with them.
You can write your own selectors and use them within the selector containers by specifying them within the <custom> tag.
First, you have to write your selector class in Java. The only
requirement it must meet in order to be a selector is that it implements
the org.apache.tools.ant.types.selectors.FileSelector
interface, which contains a single method. See
Programming Selectors in Ant for
more information.
Once that is written, you include it in your build file by using
the <custom>
tag.
Attribute | Description | Required |
classname | The name of your class that implements
org.apache.tools.ant.types.selectors.FileSelector .
|
Yes |
classpath | The classpath to use in order to load the custom selector class. If neither this classpath nor the classpathref are specified, the class will be loaded from the classpath that Ant uses. | No |
classpathref | A reference to a classpath previously defined. If neither this reference nor the classpath above are specified, the class will be loaded from the classpath that Ant uses. | No |
Here is how you use <custom>
to
use your class as a selector:
<fileset dir="${mydir}" includes="**/*"> <custom classname="com.mydomain.MySelector"> <param name="myattribute" value="myvalue"/> </custom> </fileset>
A number of core selectors can also be used as custom selectors by specifying their attributes using <param> elements. These are
org.apache.tools.ant.types.selectors.ContainsSelector
org.apache.tools.ant.types.selectors.DateSelector
org.apache.tools.ant.types.selectors.DepthSelector
org.apache.tools.ant.types.selectors.FilenameSelector
org.apache.tools.ant.types.selectors.SizeSelector
Here is the example from the Depth Selector section rewritten
to use the selector through <custom>
.
<fileset dir="${doc.path}" includes="**/*"> <custom classname="org.apache.tools.ant.types.selectors.DepthSelector"> <param name="max" value="1"/> </custom> </fileset>
Selects all files in the base directory and one directory below that.
For more details concerning writing your own selectors, consult Programming Selectors in Ant.
Copyright © 2002 Apache Software Foundation. All rights Reserved.