Eclipse中用Ant无法执行JUnit任务,报错的解决办法

最近在学习用Ant执行JUnit任务时出现以下错误.在baidu搜到了解决方案.可行.
原文地址
当build.xml中包含有任务时，直接在eclipse下Run Ant Build会出现错误，错误内容如下：

BUILD FAILED: [ECLIPSE_DIR]/workspace/[PROJECT_DIR]/build.xml:208: Could not create task or type of type: junit.

Ant could not find the task or a class this task relies upon.

This is common and has a number of causes; the usual
solutions are to read the manual pages then download and
install needed JAR files, or fix the build file:
- You have misspelt 'junit'.
Fix: check your spelling.
- The task needs an external JAR file to execute
and this is not found at the right place in the classpath.
Fix: check the documentation for dependencies.
Fix: declare the task.
- The task is an Ant optional task and optional.jar is absent
Fix: look for optional.jar in ANT_HOME/lib, download if needed
- The task was not built into optional.jar as dependent
libraries were not found at build time.
Fix: look in the JAR to verify, then rebuild with the needed
libraries, or download a release version from apache.org
- The build file was written for a later version of Ant
Fix: upgrade to at least the latest release version of Ant
- The task is not an Ant core or optional task
and needs to be declared using .

Remember that for JAR files to be visible to Ant tasks implemented
in ANT_HOME/lib, the files must be in the same directory or on the
classpath

Please neither file bug reports on this problem, nor email the
Ant mailing lists, until all of these causes have been explored,
as this is not an Ant bug.

这是因为任务在ant中是一个optional task（可选任务），并非core task（核心任务），所以我们需要junit相关支持，也就是junit.jar。

在eclipse中，选择菜单 Window --> Preferences --> Ant --> Runtime --> Global Entries 在这里加入junit.jar，这时在eclipse中运行ant时会加载junit.jar，从而解决这个问题。

说明一下:放在以下路径也可以,不过这样会和Ant的原有包混淆,作者放在Global Entries是比较好的做法.
加入其他包时也放在Global Entries下是很好的选择.^-^
Window --> Preferences --> Ant --> Runtime --> Ant Home Entries(Default)