一段完整的构造文件，即build.xml的内容

<project name="webapp" basedir="." default="dist">
     <property name="dist.name" value=http://www.mamicode.com/"demo"/>>

运行这个构造文件需要固定的目录结构，因此需要执行指定或新建文件夹的任务。这里假定构造文件处于“D:\Temp”下
build.xml.bak是系统自动生成的
WEB-INF文件夹下得有个web.xml文件，配置tomcat的时候也得有，没有的话自己手动新建写一个
web.xml文件的内容如下:
<?xml version="1.0" encoding="ISO-8859-1"?>
<!--
 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.
-->
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
                      http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
  version="3.1"
  metadata-complete="true">

  <display-name>Welcome to Tomcat</display-name>
  <description>
     Welcome to Tomcat
  </description>

</web-app>


在DOS下运行ant,看到BUILD SUCCESSFUL，说明执行构造文件成功