执行ant构建文件过后，没有修改任何相关的文件，第二遍执行ant，这时ant会提示任务已经完成的任务不再执行，记住这是任务级别的,这种情况包括在控制台上指定两个project

<?xml version="1.0" encoding="UTF-8"?>

<!-- mkdir javac jar clean 执行ant构建文件过后，没有修改任何相关的文件，第二遍执行ant，这时ant会提示任务已经完成的任务不再执行，记住这是任务级别的,这种情况包括在控制台上指定两个project-->
<project name="OurProject" default="archive" basedir="..\">

<target name="init" description="创建文件夹">
<mkdir dir="build\classes" description="用来放置类文件"/>
<mkdir dir="dist" description="用来放置打包文件"/>
</target>

<target name="compile" depends="init" description="编译源文件">
<javac srcdir="src" destdir="build/classes"></javac>
</target>

<target name="archive" depends="compile" description="打包">
<jar destfile="dist\project.jar" basedir="build\classes"></jar>
</target>

<target name="clean" depends="init" description="清除类文件和打包文件">
<delete dir="build" description="如果该文件夹有打开的文件，删除失败"></delete>
<delete dir="dist"></delete>
</target>
</project>

<!--
执行ant构建文件过后，没有修改任何相关的文件，第二遍执行ant，这时ant会提示任务已经完成的任务不再执行，
比如任务是创建文件夹，可是文件夹已经创建了（可能是第一次执行构建文件时创建的，也有可能是手工创建的））
[mkdir] Skipping D:\Workspaces\AntTest\build\classes because it already exists.
记住这是任务级别的

还有，比如，在控制台上指定两个project，D:\Workspaces\AntTest\src>ant init clean -verbose
可是执行project clean是仍会去执行project init，此时ant检查init中的任务已经执行过了，就不再执行其中的任务了，但是project init
还是会去执行，只不过没去执行其中的任务

D:\Workspaces\AntTest\src>ant init clean -verbose
Apache Ant(TM) version 1.8.2 compiled on December 20 2010
Trying the default build file: build.xml
Buildfile: D:\Workspaces\AntTest\src\build.xml
Detected Java version: 1.6 in: C:\Program Files\Java\jre6
Detected OS: Windows 7
parsing buildfile D:\Workspaces\AntTest\src\build.xml with URI = file:/D:/Workspaces/AntTest/src/build.xml
Project base dir set to: D:\Workspaces\AntTest
Build sequence for target(s) `init' is [init]
Complete build sequence is [init, clean, compile, archive, ]

init:
parsing buildfile jar:file:/E:/JavaEE/Data/Ant/apache-ant-1.8.2/lib/ant.jar!/org/apache/tools/ant/antlib.xml with URI = jar:file:/E:/JavaEE/Data/Ant/a
pache-ant-1.8.2/lib/ant.jar!/org/apache/tools/ant/antlib.xml from a zip file
[mkdir] Created dir: D:\Workspaces\AntTest\build\classes
[mkdir] Created dir: D:\Workspaces\AntTest\dist
Build sequence for target(s) `clean' is [init, clean]
Complete build sequence is [init, clean, compile, archive, ]

init:
[mkdir] Skipping D:\Workspaces\AntTest\build\classes because it already exists.
[mkdir] Skipping D:\Workspaces\AntTest\dist because it already exists.

clean:
[delete] Deleting directory D:\Workspaces\AntTest\build
[delete] Deleting directory D:\Workspaces\AntTest\build\classes
[delete] Deleting directory D:\Workspaces\AntTest\build
[delete] Deleting directory D:\Workspaces\AntTest\dist
[delete] Deleting directory D:\Workspaces\AntTest\dist

BUILD SUCCESSFUL
Total time: 0 seconds
-->