Ant macrodef : Is there a way to get the contents of an element parameter?

我正在尝试在Ant中调试macrodef。我似乎找不到一种方法来显示作为元素发送的参数的内容。

<project name='debug.macrodef'>
  <macrodef name='def.to.debug'>
    <attribute name='attr' />
    <element name='elem' />
    <sequential>
      <echo>Sure, the attribute is easy to debug: @{attr}</echo>
      <echo>The element works only in restricted cases: <elem /> </echo>
      <!-- This works only if <elem /> doesn't contain anything but a
           textnode, if there were any elements in there echo would
           complain it doesn't understand them. -->
    </sequential>
  </macrodef>

  <target name='works'>
    <def.to.debug attr='contents of attribute'>
      <elem>contents of elem</elem>
    </def.to.debug>
  </target>

  <target name='does.not.work'>
    <def.to.debug attr='contents of attribute'>
      <elem><sub.elem>contents of sub.elem</sub.elem></elem>
    </def.to.debug>
  </target>
</project>

示例运行:

$ ant works
...
works:
 [echo] Sure, the attribute is easy to debug: contents of attribute
 [echo] The element works only in restricted cases:  contents of elem
...

$ ant does.not.work
...
does.not.work:
 [echo] Sure, the attribute is easy to debug: contents of attribute

BUILD FAILED
.../build.xml:21: The following error occurred while executing this line:
.../build.xml:7: echo doesn't support the nested "sub.elem" element.
...

因此，我想我需要一种以某种方式将<elem />的内容放入属性的方法(某些扩展的macrodef实现可能具有该属性)，或者我需要一种<element-echo><elem /></element-echo>可以打印出您放入的任何XML树。有人知道其中任何一种的实现吗？当然，欢迎使用任何第三种出乎意料的方式获取数据。

最佳答案

echoxml 任务如何？

在您的示例构建文件中，替换该行

<echo>The element works only in restricted cases: <elem /> </echo>

和

<echoxml><elem /></echoxml>

结果是

$ ant does.not.work
...
does.not.work:
     [echo] Sure, the attribute is easy to debug: contents of attribute
<?xml version="1.0" encoding="UTF-8"?>
<sub.elem>contents of sub.elem</sub.elem>

也许不希望使用XML声明。您可以使用echoxml file属性将输出放置到一个临时文件中，然后读取该文件并删除声明，或者根据需要重新格式化信息。

编辑

反射(reflection)时，您可能会接近所描述的内容，例如macrodef的此连续主体

<sequential>
  <echo>Sure, the attribute is easy to debug: @{attr}</echo>
  <echoxml file="macro_elem.xml"><elem /></echoxml>
  <loadfile property="elem" srcFile="macro_elem.xml">
    <filterchain>
      <LineContainsRegexp negate="yes">
      <regexp pattern=".xml version=.1.0. encoding=.UTF-8..." />
      </LineContainsRegexp>
    </filterchain>
  </loadfile>
  <echo message="${elem}" />
</sequential>

给

$ ant does.not.work
...
does.not.work:
     [echo] Sure, the attribute is easy to debug: contents of attribute
     [echo] <sub.elem>contents of sub.elem</sub.elem>