更新了某个webapp，把新的WAR包放到webapps目录下，Tomcat就会自动把原来的同名webapp删除，并把WAR包解压，运行新的webapp。但是，有时候Tomcat并不能把旧的webapp完全删除，通常会留下WEB-INF/lib下的某个jar包，必须关闭Tomcat才能删除，这就导致自动部署失败。
解决方法是在<Context>元素中增加一个属性
antiResourceLocking="true"，默认是"false"。但是这样会带来一个问题，Tomcat在运行对应的webapp时，会把下面的文件复制到一个临时目录里，所以如果你在服务器运行的时候修改了某个JSP,Tomcat并不会发现，看到的还是修改前的那个页面。
Context elements may be explicitly defined:
- in the
$CATALINA_HOME/conf/context.xml file: the Context element information will be loaded by all webapps
- in the
$CATALINA_HOME/conf/[enginename]/[hostname]/context.xml.default file: the Context element information will be loaded by all webapps of that host
- in individual files (with a ".xml" extension) in the
$CATALINA_HOME/conf/[enginename]/[hostname]/ directory. The name of the file (less the .xml) extension will be used as the context path. Multi-level context paths may be defined using #, e.g. context#path.xml. The default web application may be defined by using a file called ROOT.xml.
- if the previous file was not found for this application, in an individual file at
/META-INF/context.xml inside the application files
- inside a Host element in the main
conf/server.xml
参考资料：
Tomcat 5.5 文档：
http://tomcat.apache.org/tomcat-5.5-doc/config/context.html关于antiResourceLocking的bug：
http://issues.apache.org/bugzilla/show_bug.cgi?id=37668