Apache Ant provides an optional task for editing property files. This is very useful when wanting to make unattended modifications to configuration files for application servers and applications. Currently, the task maintains a working property file with the ability to add properties or make changes to existing ones. Since Ant 1.8.0 comments and layout of the original properties file are preserved.
Since Ant 1.8.2 the linefeed-style of the original file will be preserved as well, as long as style used to be consistent. In general, linefeeds of the updated file will be the same as the first linefeed found when reading it.
| Attribute | Description | Required |
| file | Location of the property file to be edited | Yes |
| comment | Header for the file itself | no |
| jdkproperties | Use java.lang.Properties, which will loose comments and layout of file (default is 'false'). since Ant 1.8.0 | no |
The boolean attribute 'jdkproperties' is provided to recover the previous behaviour of the task, in which the layout and any comments in the properties file were lost by the task.
Use nested <entry>
elements to specify actual modifications to the property file itself.
| Attribute | Description | Required |
| key | Name of the property name/value pair | Yes |
| value | Value to set (=), to add (+) or subtract (-) | At least one must be specified, if operation is not delete |
| default | Initial value to set for a property if it is not
already defined in the property file. For type date, an additional keyword is allowed: "now" |
|
| type | Regard the value as : int, date or string (default) | No |
| operation | One of the following operations: for all datatypes:
for date and int only:
|
No |
| pattern | For int and date type only. If present, Values will be parsed and formatted accordingly. | No |
| unit | The unit of the value to be applied to date +/- operations.
Valid Values are:
|
No |
The rules used when setting a property value are shown below. The operation occurs after these rules are considered.
The following changes the my.properties file. Assume my.properties look like:
# A string value akey=original value # The following is a counter, which will be incremented by 1 for # each time the build is run. anint=1
After running, the file would now look like
#My properties #Wed Aug 31 13:47:19 BST 2005 # A string value akey=avalue # The following is a counter, which will be incremented by 1 for # each time the build is run. anint=2 adate=2005/08/31 13\:47 formated.int=0014 formated.date=243 13\:47
The slashes conform to the expectations of the Properties class. The file will be stored in a manner so that each character is examined and escaped if necessary.
The layout and comment of the original file is preserved. New properties are added at the end of the file. Existing properties are overwritten in place.
<propertyfile
file="my.properties"
comment="My properties">
<entry key="akey" value="avalue"/>
<entry key="adate" type="date" value="now"/>
<entry key="anint" type="int" default="0" operation="+"/>
<entry key="formated.int" type="int" default="0013" operation="+" pattern="0000"/>
<entry key="formated.date" type="date" value="now" pattern="DDD HH:mm"/>
</propertyfile>
To produce dates relative from today :
<propertyfile
file="my.properties"
comment="My properties">
<entry key="formated.date-1"
type="date" default="now" pattern="DDD"
operation="-" value="1"/>
<entry key="formated.tomorrow"
type="date" default="now" pattern="DDD"
operation="+" value="1"/>
</propertyfile>
Concatenation of strings :
<propertyfile
file="my.properties"
comment="My properties">
<entry key="progress" default="" operation="+" value="."/>
</propertyfile>
Each time called, a "." will be appended to "progress"
Pumps the project version to the next minor version (increase minor and set path=0):
<target name="nextMinorVersion">
<property
name="header"
value="##Generated file - do not modify!"/>
<propertyfile file="version.properties" comment="${header}">
<entry key="product.build.major" type="int" value="3" />
<entry key="product.build.minor" type="int" operation="+" />
<entry key="product.build.patch" type="int" value="0" />
<entry key="product.build.date" type="date" value="now" />
</propertyfile>
</target>