Ant 深入浅出

为了条理地介绍Ant，下面我分几部分来介绍Ant：

1.什么是Ant

Ant 是一种基于java的build工具，理论上来说，有点类似与（liunx）种的make，但是修复了make的缺陷，使build更加好用，更加方便。

这里有必要介绍一下为什么会产生Ant这个工具？

 既然已经有了make，gnumake，nmake，jam和其他的构建工具，为什么还有开发另外一个呢？这时因为那些工具都具有局限性，Ant的原作者（James Duncan Davidson）在开发跨平台软件时，并不能使用其中一个完成所有的任务，这就好像，在英语不是通用语言之前，你去那里，必须搞个翻译似的，降低了开发小绿绿，也急不利于大型软件开发的维护。已有的构建工具都是基于特定平台和听顶语言的，受到操作系统的限制太大。

     更重要的是，makefile有天生的痼疾，任何在liunx下调试过C程序的都碰到过可恶的Tab问题。也许一个多余的空格，就会导致一个build不能运行？你说？这方便吗？

而Ant则在所有构建工具的基于上，开发出来了跨平台，跨语言的构建工具，已成为最优秀的构建工具，几乎所有的IDE都自带了Ant工具。

2.Ant的特点

1》跨平台性，ant是基于java的，而java跨平台的性能是与庸置疑的，ant配置文件是基于XML的，而XML是格式最规范的数据格式。因而Ant跨平台的性能也不言而喻

2》功能强大

从项目的编译，打包，发布，测试到版本的控制，Ant无所不能

3》灵活方便

4》可重用性高

Ant的配置文件Build.xml以一个project为开头，以不同的target为任务模块，彼此之间相互独立，但是模块之间又可以相互联系，因而耦合性和内聚性达到了完美的统一

5》开源的

是一个优秀的开源软件

3》Ant的配置

上边简单介绍了Ant，相信没有用过的，一定很想试试，那我告诉你，如果你试过了，一定会喜欢上她的，

下面介绍一下怎么配置

和JDK配置一下，先到apache主页上下载ant最新版本，具体网址可以google/baidu。

配置大家也可以搜索，很easy的。

4》Ant如何运行呢？

和javac，java一样，直接在cmd下，输入ant就可以了，但是前提必须在该目录中有build.xml。

所以build.xml是最重要的，build.xml里详细地配置了ant如何运行和执行那些功能。

下面是我写的一个build.xml

< project name ="encrypt" default ="help" basedir ="." >
<!--
  All properties should be defined in this section.Any host-specific properties should be defined
  in the build.properties file.
  In this app,the following properties are defined in build.properties:
  1.tomcat.home === the home directory of your Tomcat installation
  2.webapps.home === the place to copy the war file to deploy it.
-->
< property file ="build.properties" />
< property name ="app.home" value ="." />
< property name ="app.name" value ="application" />
< property name ="javadoc.pkg.top" value ="encrypt" />

< property name ="src.home" value ="${app.home}/src" />
< property name ="lib.home" value ="${app.home}/lib" />
< property name ="classes.home" value ="${app.home}/classes" />
< property name ="deploy.home" value ="${app.home}/deploy" />
< property name ="doc.home" value ="${app.home}/doc" />
< property name ="web.home" value ="${app.home}/WebRoot" />

< property name ="build.home" value ="${app.home}/build" />
< property name ="build.classes" value ="${build.home}/WEB-INF/classes" />
< property name ="build.lib"   value ="${build.home}/WEB-INF/lib" />

<!-- Compilatin Classpath-->
  <!--   This section creates the classpath for compilation-->
   < path id ="compile.classpath" >
  <!-- The lib files for this application-->
   < fileset dir ="${lib.home}" >
     < include name ="*.jar" />
     < include name ="*.zip" />
   </ fileset >
  
  <!-- All files/jars that Tomcat makes available-->
   < fileset dir ="${tomcat.home}/common/lib" >
     < include name ="*.jar" />
   </ fileset >
   < pathelement location ="${tomcat.home}/common/classes" />
   </ path >
<!-- ==========help targe==========-->
  <!-- This is the default ant target executed if no target is specified.
    This helps avoid user just typed 'ant' and runing a default target
    that may not do what they are anticipating
  -->
   < target name ="help" >
     < echo message="Please specify a target![usage:ant <targetname >]"/>
     < echo message ="Here is a list of possible targets:" />
     < echo message =" clean-all .....Delete all dir,all.class and war files" />
     < echo message =" prepare .....Create directories if required" />
     < echo message =" compile .....Compiles source file" />
     < echo message =" build .....Build war file form.class and other files" />
     < echo message =" deploy .....Copy war files to the webapps directory" />
     < echo message =" javadoc .....Generates javadoc for this application" />
   </ target >

<!-- =========="clean-all" target==========-->
   < target name ="clean" >
     < delete dir ="${build.home}" />
     < delete dir ="${classes.home}" />
     < delete dir ="${deploy.home}" />
    
    <!-- cannot delete directory if tomcat is runing-->
     < delete dir ="${webapps.home}/${app.home}" failonerror ="false" />
     < delete dir ="${webapps.home}/S{app.name}.war" />
    
    <!-- delete javadoc-->
     < delete dir ="${doc.home}" />
   </ target >
<!-- -==========="prepare" target===========-->
  <!-- This target is executed prior to any of the later targets
     to make sure the directories exist.It only creates them if
     they need to be created...
    Other,similar,preparation steps can be placed here
  -->
   < target name ="prepare" >
     < echo message ="Tomcat Home =${tomcat.home}" />
     < echo message = "webapps Home = ${webapps.home}" />
    
     < mkdir dir ="${classes.home}" />
     < mkdir dir ="${deploy.home}" />
     < mkdir dir ="${doc.home}" />
     < mkdir dir ="${doc.home}/api" />
    
     < mkdir dir ="${build.home}" />
     < mkdir dir ="${build.home}/WEB-INF" />
     < mkdir dir ="${build.home}/WEB-INF/classes" />
     < mkdir dir ="${build.home}/WEB-INF/lib" />
   </ target >
  
<!-- =========="compile" target==========-->
  <!-- This only compiles java files that are newer
    than their corresponing.class files
  -->
   < target name ="compile" depends ="prepare" >
     < javac srcdir ="${src.home}" destdir ="${classes.home}" debug ="yes" >
       < classpath refid = "compile.classpath" />
     </ javac >
   </ target >

<!-- ============"build" target=============-->
  <!-- This target builds the war file for the application by
    first building the directory structure of the application
    in ${build.home} and then creating the war file using the
    ant <war> task
  -->
   < target name ="build" depends ="compile" >
    <!-- Copy all the wabapp content(jsp's,html,tld's,xml,etc...-->
     < copy todir ="${build.home}" >
       < fileset dir ="${web.home}" />
     </ copy >
    
    <!-- copy all java class files-->
     < copy todir ="${build.home}/WEB-INF/classes" >
       < fileset dir ="${classes.home}" />
     </ copy >
    
    <!-- Now, copy all the properties files,etc that go on the classpath-->
     < copy todir ="${build.home}/WEB-INF/classes" >
       < fileset dir ="${src.home}" >
         < include name ="**/*.properties" />
         < include name ="**/*.prop" />
       </ fileset >
     </ copy >
    
    <!-- Now,copy all the jar files we need-->
     < copy todir ="${build.home}/WEB-INF/lib" >
       < fileset dir ="${lib.home}" />
     </ copy >
    
    <!-- create the <war> file-->
     < jar jarfile ="${deploy.home}/${app.name}.war" basedir ="${build.home}" />
   </ target >
<!-- ================"deploy" target============-->
  <!-- This target simply copies the war file from the deploy
    directory into the Tomcat webapps directory.
  -->
   < target name ="deploy" depends ="build" >
    
    <!-- copy the contents of the build directory-->
     < copy todir ="${webapps.home}" file ="${deploy.home}/${app.name}.war" />
   </ target >

<!-- ================="doc" target=========-->
  <!-- This task create javadoc.It is dependent upon only the 'compile' target
    it is not executed in a normal build.As a result,the target needs to
    be run on its own.
  -->
   < target name ="javadoc" depends ="compile" >
     < javadoc sourcepath ="${src.home}" destdir ="${doc.home}/api"
         packagenames ="${javadoc.pkg.top}.*" />
   </ target >
</ project >
    

下边是build.properties的文件内容：

tomcat.home=F:\\Java\\Tomcat 5.5
webapps.home=F:\\Java\\Tomcat 5.5\\webapps

大家如果仔细看了build.xml，会发现build.xml只有个project，下边会有几个target。确实是这样，每个build.xml只有一个project，属性default必须的。

而每个target执行不同的功能，具体的语法，大家可以看apace ant的介绍。过后我在写。今天就写到这里。只是一点小小的认识，抛砖引玉而已！

O(∩_∩)O