如何在Ant中提取子字符串

 <project>
  <scriptdef name="substring" language="javascript">
     <attribute name="text" />
     <attribute name="start" />
     <attribute name="end" />
     <attribute name="property" />
     <![CDATA[
       var text = attributes.get("text");
       var start = attributes.get("start");
       var end = attributes.get("end") || text.length();
       project.setProperty(attributes.get("property"), text.substring(start, end));
     ]]>
  </scriptdef>
  ........
  <target ...>
     <substring text="asdfasdfasdf" start="2" end="10" property="subtext" />
     <echo message="subtext = ${subtext}" />
  </target>
 </project>

PropertyRegex from Ant-Contrib .

   <propertyregex property="destinationProperty"
              input="${sourceProperty}"
              regexp="regexToMatchSubstring"
              select="\1"
              casesensitive="false" />

由于我更喜欢使用vanilla Ant,所以我使用了一个临时文件。适用于任何地方,您可以利用replaceregex来删除字符串中的一部分 想要。修改Git消息的示例:

    <exec executable="git" output="${git.describe.file}" errorproperty="git.error" failonerror="true">
        <arg value="describe"/>
        <arg value="--tags" />
        <arg value="--abbrev=0" />
    </exec>
    <loadfile srcfile="${git.describe.file}" property="git.workspace.specification.version">
        <filterchain>
           <headfilter lines="1" skip="0"/>
           <tokenfilter>
              <replaceregex pattern="\.[0-9]+$" replace="" flags="gi"/>
           </tokenfilter>
           <striplinebreaks/>
        </filterchain>
    </loadfile>

我想一个简单的香草方法是:

<loadresource property="destinationProperty">
    <concat>${sourceProperty}</concat>
    <filterchain>
        <replaceregex pattern="regexToMatchSubstring" replace="\1" />
    </filterchain>
</loadresource>

public class SubstringTask extends Task {

    public void execute() throws BuildException {
        String input = getProject().getProperty("oldproperty");
        String output = process(input);
        getProject().setProperty("newproperty", output);
    }
}

剩下什么来实施 String process(String) oldproperty 和 newproperty 值)

为此,我会使用脚本任务,我更喜欢ruby,例如 剪掉前3个字符=

<project>
  <property name="mystring" value="foobarfoobaz"/>  
   <target name="main"> 
    <script language="ruby">
     $project.setProperty 'mystring', $mystring[3..-1]
    </script>
    <echo>$${mystring} == ${mystring}</echo>
   </target>    
  </project>

输出=

main:
     [echo] ${mystring} == barfoobaz

将ant api与project.setProperty()方法一起用于现有的 属性将覆盖它,这样您就可以绕过标准ant了