ant 打包问题
直接myeclipse ant出现：
Buildfile: F:\Workspaces\MyEclipse 7.0\Basic_Struts2_Ant\build.xml
clean:
  [delete] Deleting directory F:\Workspaces\MyEclipse 7.0\Basic_Struts2_Ant\build
init:
  [mkdir] Created dir: F:\Workspaces\MyEclipse 7.0\Basic_Struts2_Ant\build
compile:
  [mkdir] Created dir: F:\Workspaces\MyEclipse 7.0\Basic_Struts2_Ant\build\WEB-INF\classes
  [javac] Compiling 2 source files to F:\Workspaces\MyEclipse 7.0\Basic_Struts2_Ant\build\WEB-INF\classes

BUILD FAILED
F:\Workspaces\MyEclipse 7.0\Basic_Struts2_Ant\build.xml:69: F:\Workspaces\MyEclipse 7.0\Basic_Struts2_Ant\lib_external not found.

Total time: 235 milliseconds

build.xml:
<?xml version="1.0"?>


<!-- ====================================================================== 
  Date: January 2010
   
  Project: Struts 2 Basic Application
   
  Author: Bruce Phillips
  ====================================================================== -->



<project name="Basic_Struts2_Ant" default="archive" basedir=".">

  <description>
  Basic Struts 2 Java Web Application
  </description>

<property file="build.properties"/>
   


<!-- ==================== Clean Target ==================================== -->

<!--
The "clean" target deletes any previous "build" and "dist" directory,
so that you can be ensured the application can be built from scratch.
-->
<target name="clean" description="Delete old build and dist directories">
<delete dir="${dist.home}"/>
<delete dir="${build.home}"/>
</target>

<!-- ==================== Init Target ================================== -->

<!--

The "init" target is used to create the "build" destination directory,
Normally, this task is executed indirectly when needed.

-->
<target name="init" depends="clean" description="Create build directory">

<mkdir dir="${build.home}" />

</target>

<!-- ==================== Compile Target ================================== -->

<!--

The "compile" target transforms source files (from your "src" directory)
into class files in the appropriate location in the build directory.
This example assumes that you will be including your classes in an
unpacked directory hierarchy under "/WEB-INF/classes".

-->
<target name="compile" depends="init" description="Compile Java sources">


<mkdir dir="${build.home}/WEB-INF/classes" />

<javac srcdir="${source.home}"
destdir="${build.home}/WEB-INF/classes"
debug="${compile.debug}"
deprecation="${compile.deprecation}"
optimize="${compile.optimize}"
source="1.6" target="1.6">

<classpath>
<path>
<fileset dir="${lib.home}" />
<fileset dir="${lib.external}" />
</path>
</classpath>

</javac>

</target>

<!-- ==================== Build Target ================================== --&