ant属性文件被属性任务覆盖

Question

I'm trying to set some global properties in an ant project.

<property file="env/${deploy.servername}.properties" />
<property name="deploy.username" value="${env.USERNAME}" />

As the ant task is being triggered by a jenkins parameterized project env.USERNAME is always set but not always correct.

My goal with this design is that if the property deploy.username is present in the file at deploy.servername the file should set the property and as ant shouldn't allow the property to be reset the value at env.USERNAME should be ignored.

Unfortunately the value provided by env.USERNAME is alway the value used by the script. Why? Does ant evaluate property name=* before property file=* ? Is a property set by property file=* mutable?

Thanks for the help

Answer 1

In ant a property once set is immutable by design. There is no specific order when using different mechanisms to create a property - the first declaration of the property wins.
Given propertyfile foo.properties has :

JAVA_HOME=some/path

Example script

<project>

  <property file="foo.properties"/>
  <property name="JAVA_HOME" value="foobar"/>

  <property environment="env"/>
  <property name="JAVA_HOME" value="${env.JAVA_HOME}"/>

  <echo>$${JAVA_HOME} => ${JAVA_HOME}</echo>

</project>

output

[echo] ${JAVA_HOME} => some/path

That means the property is already defined somewhere else.
Put in that line :

<echo>$${deploy.username} => ${deploy.username}</echo>

before :

<property file="env/${deploy.servername}.properties"/>

to see if the property already exists.