用ant编译tomcat源码时出现错误

不是很了解ant，按教程做的
下载了tomcat源码来编译
出现下面这些错误
请教怎么解决
D:\opensource\tomcat\src\java\org\apache\jasper\compiler\JDTCompiler.java:37: 软件包 org.eclipse.jdt.core.compiler 不存在
    [javac] import org.eclipse.jdt.core.compiler.IProblem;
    [javac]                                     ^
    [javac] D:\opensource\tomcat\src\java\org\apache\jasper\compiler\JDTCompiler.java:38: 软件包 org.eclipse.jdt.internal.compiler 不存在
    [javac] import org.eclipse.jdt.internal.compiler.ClassFile;
    [javac]                                         ^
    [javac] D:\opensource\tomcat\src\java\org\apache\jasper\compiler\JDTCompiler.java:39: 软件包 org.eclipse.jdt.internal.compiler 不存在
    [javac] import org.eclipse.jdt.internal.compiler.CompilationResult;
    [javac]                                         ^
    [javac] D:\opensource\tomcat\src\java\org\apache\jasper\compiler\JDTCompiler.java:40: 软件包 org.eclipse.jdt.internal.compiler 不存在
    [javac] import org.eclipse.jdt.internal.compiler.Compiler;
    [javac]                                         ^
    [javac] D:\opensource\tomcat\src\java\org\apache\jasper\compiler\JDTCompiler.java:41: 软件包 org.eclipse.jdt.internal.compiler 不存在
    [javac] import org.eclipse.jdt.internal.compiler.DefaultErrorHandlingPolicies;
    [javac]                                         ^
    [javac] D:\opensource\tomcat\src\java\org\apache\jasper\compiler\JDTCompiler.java:42: 软件包 org.eclipse.jdt.internal.compiler 不存在
    [javac] import org.eclipse.jdt.internal.compiler.ICompilerRequestor;
    [javac]                                         ^
    [javac] D:\opensource\tomcat\src\java\org\apache\jasper\compiler\JDTCompiler.java:43: 软件包 org.eclipse.jdt.internal.compiler 不存在
    [javac] import org.eclipse.jdt.internal.compiler.IErrorHandlingPolicy;
    [javac]                                         ^
    [javac] D:\opensource\tomcat\src\java\org\apache\jasper\compiler\JDTCompiler.java:44: 软件包 org.eclipse.jdt.internal.compiler 不存在
    [javac] import org.eclipse.jdt.internal.compiler.IProblemFactory;
    [javac]                                         ^
    [javac] D:\opensource\tomcat\src\java\org\apache\jasper\compiler\JDTCompiler.java:45: 软件包 org.eclipse.jdt.internal.compiler.classfmt 不存在
    [javac] import org.eclipse.jdt.internal.compiler.classfmt.ClassFileReader;
    [javac]                                                  ^
    [javac] D:\opensource\tomcat\src\java\org\apache\jasper\compiler\JDTCompiler.java:46: 软件包 org.eclipse.jdt.internal.compiler.env 不存在
    [javac] import org.eclipse.jdt.internal.compiler.env.ICompilationUnit;
    [javac]                                             ^
    [javac] D:\opensource\tomcat\src\java\org\apache\jasper\compiler\JDTCompiler.java:47: 软件包 org.eclipse.jdt.internal.compiler.env 不存在
    [javac] import org.eclipse.jdt.internal.compiler.env.INameEnvironment;
    [javac]                                             ^
    [javac]