Ant的实现原理
在build.xml中，我们使用一句简单的脚本就可以执行想要做的事情，比如说：
<delete dir="d://testMKDir" />
上面这句脚本将删除 d://testMKDir
很神奇，有木有？
想知道怎么实现的吗？
继续往下看....
将ant.jar反编译一下，我看看到如下东东：
原来ant将这些操作都封装了起来。这些操作都有一个共通的基类叫Task(抽象类)。
public void execute() throws BuildException{
}
其中有个空实现的execute方法，为什么提这个，后面你就知道了。
下面来测试一下：
/*
* <delete dir="d://testMKDir" />
* <mkdir dir="d://testMKDir" />
* delete=org.apache.tools.ant.taskdefs.Delete
* mkdir=org.apache.tools.ant.taskdefs.Mkdir
*/public static void execute(String obj, String path) {
try {
Method setMethod = null;
Class classObj = Class.forName(obj);
Object objectCopy = classObj.getConstructor(new Class[] {})
.newInstance(new Object[] {});
setMethod = classObj.getMethod("setDir", new Class[] { File.class });
setMethod.invoke(objectCopy, new File(path));
Task task = (Task) objectCopy;
task.execute();
} catch (Exception e) {
System.out.println(e);
}
}
调用上面的方法：
execute("org.apache.tools.ant.taskdefs.Mkdir", "d://testMKDir");
execute("org.apache.tools.ant.taskdefs.Delete", "d://testMKDir");
执行之后，控制台输出：
Created dir: d:\testMKDir Deleting directory d:\testMKDir
由上可知，build.xml中的执行过程大致为：
以解析<mkdir dir = "d://testMKDir" />为例：
- 解析到了mkdir，就根据属性文件defaults.properties查找到： mkdir=org.apache.tools.ant.taskdefs.Mkdir
- 通过反射创建org.apache.tools.ant.taskdefs.Mkdir对象
- 获取其属性比如File dir;
- 根据属性设置方法setDir(File dir);
- 最后用其父类调用execute()方法
defaults.properties文件在org.apache.tools.ant.types包下，内容如下：
defaults.properties # Licensed to the Apache Software Foundation (ASF) under one or more # contributor license agreements. See the NOTICE file distributed with # this work for additional information regarding copyright ownership. # The ASF licenses this file to You under the Apache License, Version 2.0 # (the "License"); you may not use this file except in compliance with # the License. You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. # # standard ant tasks ant=org.apache.tools.ant.taskdefs.Ant antcall=org.apache.tools.ant.taskdefs.CallTarget antstructure=org.apache.tools.ant.taskdefs.AntStructure antversion=org.apache.tools.ant.taskdefs.condition.AntVersion apply=org.apache.tools.ant.taskdefs.Transform available=org.apache.tools.ant.taskdefs.Available basename=org.apache.tools.ant.taskdefs.Basename buildnumber=org.apache.tools.ant.taskdefs.BuildNumber bunzip2=org.apache.tools.ant.taskdefs.BUnzip2 bzip2=org.apache.tools.ant.taskdefs.BZip2 checksum=org.apache.tools.ant.taskdefs.Checksum chmod=org.apache.tools.ant.taskdefs.Chmod classloader=org.apache.tools.ant.taskdefs.Classloader concat=org.apache.tools.ant.taskdefs.Concat condition=org.apache.tools.ant.taskdefs.ConditionTask copy=org.apache.tools.ant.taskdefs.Copy cvs=org.apache.tools.ant.taskdefs.Cvs cvschangelog=org.apache.tools.ant.taskdefs.cvslib.ChangeLogTask cvspass=org.apache.tools.ant.taskdefs.CVSPass cvstagdiff=org.apache.tools.ant.taskdefs.cvslib.CvsTagDiff cvsversion=org.apache.tools.ant.taskdefs.cvslib.CvsVersion defaultexcludes=org.apache.tools.ant.taskdefs.DefaultExcludes delete=org.apache.tools.ant.taskdefs.Delete dependset=org.apache.tools.ant.taskdefs.DependSet diagnostics=org.apache.tools.ant.taskdefs.DiagnosticsTask dirname=org.apache.tools.ant.taskdefs.Dirname ear=org.apache.tools.ant.taskdefs.Ear echo=org.apache.tools.ant.taskdefs.Echo exec=org.apache.tools.ant.taskdefs.ExecTask fail=org.apache.tools.ant.taskdefs.Exit filter=org.apache.tools.ant.taskdefs.Filter fixcrlf=org.apache.tools.ant.taskdefs.FixCRLF genkey=org.apache.tools.ant.taskdefs.GenerateKey get=org.apache.tools.ant.taskdefs.Get gunzip=org.apache.tools.ant.taskdefs.GUnzip gzip=org.apache.tools.ant.taskdefs.GZip import=org.apache.tools.ant.taskdefs.ImportTask input=org.apache.tools.ant.taskdefs.Input jar=org.apache.tools.ant.taskdefs.Jar java=org.apache.tools.ant.taskdefs.Java javac=org.apache.tools.ant.taskdefs.Javac javadoc=org.apache.tools.ant.taskdefs.Javadoc length=org.apache.tools.ant.taskdefs.Length loadfile=org.apache.tools.ant.taskdefs.LoadFile loadproperties=org.apache.tools.ant.taskdefs.LoadProperties loadresource=org.apache.tools.ant.taskdefs.LoadResource macrodef=org.apache.tools.ant.taskdefs.MacroDef mail=org.apache.tools.ant.taskdefs.email.EmailTask manifest=org.apache.tools.ant.taskdefs.ManifestTask manifestclasspath=org.apache.tools.ant.taskdefs.ManifestClassPath mkdir=org.apache.tools.ant.taskdefs.Mkdir move=org.apache.tools.ant.taskdefs.Move nice=org.apache.tools.ant.taskdefs.Nice parallel=org.apache.tools.ant.taskdefs.Parallel patch=org.apache.tools.ant.taskdefs.Patch pathconvert=org.apache.tools.ant.taskdefs.PathConvert presetdef=org.apache.tools.ant.taskdefs.PreSetDef property=org.apache.tools.ant.taskdefs.Property record=org.apache.tools.ant.taskdefs.Recorder replace=org.apache.tools.ant.taskdefs.Replace retry=org.apache.tools.ant.taskdefs.Retry rmic=org.apache.tools.ant.taskdefs.Rmic sequential=org.apache.tools.ant.taskdefs.Sequential signjar=org.apache.tools.ant.taskdefs.SignJar sleep=org.apache.tools.ant.taskdefs.Sleep sql=org.apache.tools.ant.taskdefs.SQLExec subant=org.apache.tools.ant.taskdefs.SubAnt sync=org.apache.tools.ant.taskdefs.Sync tar=org.apache.tools.ant.taskdefs.Tar taskdef=org.apache.tools.ant.taskdefs.Taskdef tempfile=org.apache.tools.ant.taskdefs.TempFile touch=org.apache.tools.ant.taskdefs.Touch tstamp=org.apache.tools.ant.taskdefs.Tstamp truncate=org.apache.tools.ant.taskdefs.Truncate typedef=org.apache.tools.ant.taskdefs.Typedef unjar=org.apache.tools.ant.taskdefs.Expand untar=org.apache.tools.ant.taskdefs.Untar unwar=org.apache.tools.ant.taskdefs.Expand unzip=org.apache.tools.ant.taskdefs.Expand uptodate=org.apache.tools.ant.taskdefs.UpToDate waitfor=org.apache.tools.ant.taskdefs.WaitFor war=org.apache.tools.ant.taskdefs.War whichresource=org.apache.tools.ant.taskdefs.WhichResource xmlproperty=org.apache.tools.ant.taskdefs.XmlProperty xslt=org.apache.tools.ant.taskdefs.XSLTProcess zip=org.apache.tools.ant.taskdefs.Zip # optional tasks antlr=org.apache.tools.ant.taskdefs.optional.ANTLR apt=org.apache.tools.ant.taskdefs.Apt attrib=org.apache.tools.ant.taskdefs.optional.windows.Attrib blgenclient=org.apache.tools.ant.taskdefs.optional.ejb.BorlandGenerateClient cab=org.apache.tools.ant.taskdefs.optional.Cab cccheckin=org.apache.tools.ant.taskdefs.optional.clearcase.CCCheckin cccheckout=org.apache.tools.ant.taskdefs.optional.clearcase.CCCheckout cclock=org.apache.tools.ant.taskdefs.optional.clearcase.CCLock ccmcheckin=org.apache.tools.ant.taskdefs.optional.ccm.CCMCheckin ccmcheckintask=org.apache.tools.ant.taskdefs.optional.ccm.CCMCheckinDefault ccmcheckout=org.apache.tools.ant.taskdefs.optional.ccm.CCMCheckout ccmcreatetask=org.apache.tools.ant.taskdefs.optional.ccm.CCMCreateTask ccmkattr=org.apache.tools.ant.taskdefs.optional.clearcase.CCMkattr ccmkbl=org.apache.tools.ant.taskdefs.optional.clearcase.CCMkbl ccmkdir=org.apache.tools.ant.taskdefs.optional.clearcase.CCMkdir ccmkelem=org.apache.tools.ant.taskdefs.optional.clearcase.CCMkelem ccmklabel=org.apache.tools.ant.taskdefs.optional.clearcase.CCMklabel ccmklbtype=org.apache.tools.ant.taskdefs.optional.clearcase.CCMklbtype ccmreconfigure=org.apache.tools.ant.taskdefs.optional.ccm.CCMReconfigure ccrmtype=org.apache.tools.ant.taskdefs.optional.clearcase.CCRmtype ccuncheckout=org.apache.tools.ant.taskdefs.optional.clearcase.CCUnCheckout ccunlock=org.apache.tools.ant.taskdefs.optional.clearcase.CCUnlock ccupdate=org.apache.tools.ant.taskdefs.optional.clearcase.CCUpdate chgrp=org.apache.tools.ant.taskdefs.optional.unix.Chgrp chown=org.apache.tools.ant.taskdefs.optional.unix.Chown csc=org.apache.tools.ant.taskdefs.optional.dotnet.CSharp ddcreator=org.apache.tools.ant.taskdefs.optional.ejb.DDCreator depend=org.apache.tools.ant.taskdefs.optional.depend.Depend echoproperties=org.apache.tools.ant.taskdefs.optional.EchoProperties echoxml=org.apache.tools.ant.taskdefs.EchoXML ejbc=org.apache.tools.ant.taskdefs.optional.ejb.Ejbc ejbjar=org.apache.tools.ant.taskdefs.optional.ejb.EjbJar ftp=org.apache.tools.ant.taskdefs.optional.net.FTP ilasm=org.apache.tools.ant.taskdefs.optional.dotnet.Ilasm ildasm=org.apache.tools.ant.taskdefs.optional.dotnet.Ildasm image=org.apache.tools.ant.taskdefs.optional.image.Image importtypelib=org.apache.tools.ant.taskdefs.optional.dotnet.ImportTypelib iplanet-ejbc=org.apache.tools.ant.taskdefs.optional.ejb.IPlanetEjbcTask jarlib-available=org.apache.tools.ant.taskdefs.optional.extension.JarLibAvailableTask jarlib-display=org.apache.tools.ant.taskdefs.optional.extension.JarLibDisplayTask jarlib-manifest=org.apache.tools.ant.taskdefs.optional.extension.JarLibManifestTask jarlib-resolve=org.apache.tools.ant.taskdefs.optional.extension.JarLibResolveTask javacc=org.apache.tools.ant.taskdefs.optional.javacc.JavaCC javah=org.apache.tools.ant.taskdefs.optional.Javah jdepend=org.apache.tools.ant.taskdefs.optional.jdepend.JDependTask jjdoc=org.apache.tools.ant.taskdefs.optional.javacc.JJDoc jjtree=org.apache.tools.ant.taskdefs.optional.javacc.JJTree jsharpc=org.apache.tools.ant.taskdefs.optional.dotnet.JSharp junit=org.apache.tools.ant.taskdefs.optional.junit.JUnitTask junitreport=org.apache.tools.ant.taskdefs.optional.junit.XMLResultAggregator makeurl=org.apache.tools.ant.taskdefs.MakeUrl native2ascii=org.apache.tools.ant.taskdefs.optional.Native2Ascii netrexxc=org.apache.tools.ant.taskdefs.optional.NetRexxC p4add=org.apache.tools.ant.taskdefs.optional.perforce.P4Add p4change=org.apache.tools.ant.taskdefs.optional.perforce.P4Change p4counter=org.apache.tools.ant.taskdefs.optional.perforce.P4Counter p4delete=org.apache.tools.ant.taskdefs.optional.perforce.P4Delete p4edit=org.apache.tools.ant.taskdefs.optional.perforce.P4Edit p4fstat=org.apache.tools.ant.taskdefs.optional.perforce.P4Fstat p4have=org.apache.tools.ant.taskdefs.optional.perforce.P4Have p4integrate=org.apache.tools.ant.taskdefs.optional.perforce.P4Integrate p4label=org.apache.tools.ant.taskdefs.optional.perforce.P4Label p4labelsync=org.apache.tools.ant.taskdefs.optional.perforce.P4Labelsync p4reopen=org.apache.tools.ant.taskdefs.optional.perforce.P4Reopen p4resolve=org.apache.tools.ant.taskdefs.optional.perforce.P4Resolve p4revert=org.apache.tools.ant.taskdefs.optional.perforce.P4Revert p4submit=org.apache.tools.ant.taskdefs.optional.perforce.P4Submit p4sync=org.apache.tools.ant.taskdefs.optional.perforce.P4Sync propertyfile=org.apache.tools.ant.taskdefs.optional.PropertyFile pvcs=org.apache.tools.ant.taskdefs.optional.pvcs.Pvcs replaceregexp=org.apache.tools.ant.taskdefs.optional.ReplaceRegExp resourcecount=org.apache.tools.ant.taskdefs.ResourceCount rexec=org.apache.tools.ant.taskdefs.optional.net.RExecTask rpm=org.apache.tools.ant.taskdefs.optional.Rpm schemavalidate=org.apache.tools.ant.taskdefs.optional.SchemaValidate scp=org.apache.tools.ant.taskdefs.optional.ssh.Scp script=org.apache.tools.ant.taskdefs.optional.Script scriptdef=org.apache.tools.ant.taskdefs.optional.script.ScriptDef serverdeploy=org.apache.tools.ant.taskdefs.optional.j2ee.ServerDeploy setproxy=org.apache.tools.ant.taskdefs.optional.net.SetProxy soscheckin=org.apache.tools.ant.taskdefs.optional.sos.SOSCheckin soscheckout=org.apache.tools.ant.taskdefs.optional.sos.SOSCheckout sosget=org.apache.tools.ant.taskdefs.optional.sos.SOSGet soslabel=org.apache.tools.ant.taskdefs.optional.sos.SOSLabel sound=org.apache.tools.ant.taskdefs.optional.sound.SoundTask splash=org.apache.tools.ant.taskdefs.optional.splash.SplashTask sshexec=org.apache.tools.ant.taskdefs.optional.ssh.SSHExec stcheckin=org.apache.tools.ant.taskdefs.optional.starteam.StarTeamCheckin stcheckout=org.apache.tools.ant.taskdefs.optional.starteam.StarTeamCheckout stlabel=org.apache.tools.ant.taskdefs.optional.starteam.StarTeamLabel stlist=org.apache.tools.ant.taskdefs.optional.starteam.StarTeamList stylebook=org.apache.tools.ant.taskdefs.optional.StyleBook symlink=org.apache.tools.ant.taskdefs.optional.unix.Symlink telnet=org.apache.tools.ant.taskdefs.optional.net.TelnetTask translate=org.apache.tools.ant.taskdefs.optional.i18n.Translate vbc=org.apache.tools.ant.taskdefs.optional.dotnet.VisualBasicCompile verifyjar=org.apache.tools.ant.taskdefs.VerifyJar vssadd=org.apache.tools.ant.taskdefs.optional.vss.MSVSSADD vsscheckin=org.apache.tools.ant.taskdefs.optional.vss.MSVSSCHECKIN vsscheckout=org.apache.tools.ant.taskdefs.optional.vss.MSVSSCHECKOUT vsscp=org.apache.tools.ant.taskdefs.optional.vss.MSVSSCP vsscreate=org.apache.tools.ant.taskdefs.optional.vss.MSVSSCREATE vssget=org.apache.tools.ant.taskdefs.optional.vss.MSVSSGET vsshistory=org.apache.tools.ant.taskdefs.optional.vss.MSVSSHISTORY vsslabel=org.apache.tools.ant.taskdefs.optional.vss.MSVSSLABEL wljspc=org.apache.tools.ant.taskdefs.optional.jsp.WLJspc wlrun=org.apache.tools.ant.taskdefs.optional.ejb.WLRun wlstop=org.apache.tools.ant.taskdefs.optional.ejb.WLStop wsdltodotnet=org.apache.tools.ant.taskdefs.optional.dotnet.WsdlToDotnet xmlvalidate=org.apache.tools.ant.taskdefs.optional.XMLValidateTask # deprecated ant tasks (kept for back compatibility) copydir=org.apache.tools.ant.taskdefs.Copydir copyfile=org.apache.tools.ant.taskdefs.Copyfile copypath=org.apache.tools.ant.taskdefs.CopyPath deltree=org.apache.tools.ant.taskdefs.Deltree execon=org.apache.tools.ant.taskdefs.ExecuteOn javadoc2=org.apache.tools.ant.taskdefs.Javadoc jlink=org.apache.tools.ant.taskdefs.optional.jlink.JlinkTask jspc=org.apache.tools.ant.taskdefs.optional.jsp.JspC mimemail=org.apache.tools.ant.taskdefs.optional.net.MimeMail rename=org.apache.tools.ant.taskdefs.Rename renameext=org.apache.tools.ant.taskdefs.optional.RenameExtensions starteam=org.apache.tools.ant.taskdefs.optional.scm.AntStarTeamCheckOut style=org.apache.tools.ant.taskdefs.XSLTProcess WsdlToDotnet=org.apache.tools.ant.taskdefs.optional.dotnet.WsdlToDotnet
类似的，测试一下copy方法如下
public static void execute_Copy(String obj, String path,String destPath) {
try {
Method setMethod = null;
Method setDestMethod = null;
Class classObj = Class.forName(obj);
Object objectCopy = classObj.getConstructor(new Class[] {})
.newInstance(new Object[] {});
setMethod = classObj.getMethod("setFile", new Class[] { File.class });
setMethod.invoke(objectCopy, new File(path));
setDestMethod = classObj.getMethod("setTofile", new Class[] { File.class });
setDestMethod.invoke(objectCopy, new File(destPath));
Task task = (Task) objectCopy;
task.execute();
} catch (Exception e) {
System.out.println(e);
}
}
以上测试基于ant 1.7版，其他版本应该也差不多..