Cause: the class org.apache.tools.ant.taskdefs.optional.ANTLR was not found.

　　具体错误：

gluegen.build.javase:

generate.java:

BUILD FAILED
/home/tsit/jogamp232-loongarch64/gluegen/make/build.xml:957: The following error occurred while executing this line:
/home/tsit/jogamp232-loongarch64/gluegen/make/build.xml:694: The following error occurred while executing this line:
/home/tsit/jogamp232-loongarch64/gluegen/make/build.xml:653: Problem: failed to create task or type antlr
Cause: the class org.apache.tools.ant.taskdefs.optional.ANTLR was not found.
        This looks like one of Ant's optional components.
Action: Check that the appropriate optional JAR exists in
        -/home/tsit/apache-ant-1.10.11/dist/lib
        -/home/tsit/.ant/lib
        -a directory added on the command line with the -lib argument

Do not panic, this is a common problem.
The commonest cause is a missing JAR.

This is not a bug; it is a configuration problem

　　什么意思？就是ant缺少东西。原因是吾自己下载编译了ant（因为到目前为止，loongarch64平台没有ant可更新安装），实际上lib的内容不对。解决办法：

• 检查版本

Apache Ant(TM) version 1.10.5 compiled on August 27 2018

• 下载ant

Index of /ant/binaries

Apache Ant - Binary Distributions

 Index of /dist/ant/binaries

这个链接可以下载各种老版本。 

• 复制缺少的jar

我们只复制需要的jar，如ant-antlr.jar。目录应该是/usr/share/ant/lib