可能重复：
Ivy fails to resolve a dependancy, unable to find cause
我正在尝试运行以下构建任务（initIvy）：
<?xml version="1.0" encoding="UTF-8"?>
<project name="myproject-build" default="package" basedir=".." xmlns:ivy="antlib:org.apache.ivy.ant">
<property file="build/build.properties"/>
<property environment="env"/>
<!-- Ant library path, including all of its plugins. -->
<path id="ant.lib.path">
<fileset dir="${env.ANT_HOME}/lib" includes="*.jar"/>
</path>
<!-- CONFIGURE IVY -->
<taskdef resource="org/apache/ivy/ant/antlib.xml"
uri="antlib:org.apache.ivy.ant" classpathref="ant.lib.path"/>
<!-- Use Ivy tasks to resolve dependencies into the local Ivy cache. -->
<target name="initIvy">
<!-- Initialize Ivy and connect to host repository. -->
<echo message="Initializing Apache Ivy and connecting to the host repository."/>
<ivy:settings url="${ivy.std.repo.settings.url}" realm="${ivy.std.repo.realm}" username="${ivy.std.repo.username}" passwd="${ivy.std.repo.password}"/>
<!-- Clear/flush the Ivy cache. -->
<echo message="Cleaning the local Ivy cache for the current build."/>
<ivy:cleancache/>
</target>
<!-- Rest of buildfile omitted for brevity. -->
</project>
我运行ant -buildfile build.xml initIvy时，会得到以下输出：
Buildfile: /<path-to-my-project>/build/build.xml
[taskdef] Could not load definitions from resource org/apache/ivy/ant/antlib.xml. It could not be found.
initIvy:
[echo] Initializing Apache Ivy and connecting to the host repository.
BUILD FAILED
/<path-to-my-project>/build/build.xml:81: Problem: failed to create task or type antlib:org.apache.ivy.ant:settings
Cause: The name is undefined.
Action: Check the spelling.
Action: Check that any custom tasks/types have been declared.
Action: Check that any <presetdef>/<macrodef> declarations have taken place.
No types or tasks have been defined in this namespace yet
This appears to be an antlib declaration.
Action: Check that the implementing library exists in one of:
-/<path-to-my-ANT_HOME>/lib
-/home/myUser/.ant/lib
-a directory added on the command line with the -lib argument
因此，我猜测我下载的 Ant 版本不包括 Antlib，现在我正在使用 Ivy（它使用 Antlib），构建过程出现问题？
如果这是一个 Antlib 问题，那么我认为我需要使用这里提供的其中一个发行版。如果是这样，请有人确认我应该使用哪个（仅包含 Antlib 而不包含其他内容），并确认安装过程；例如，是否只需将正确的 JAR 放置在 ${ANT_HOME}/lib 中？等等。
如果这是一个 Ivy 问题，那么有人能否指导我正确的方向呢？
如果这既不是 Antlib 也不是 Ivy，那么直接回答上面的问题即可。提前感谢！