jetty锁定文件
jetty在运行是会对静态文件锁定，导致无法修改
jetty官方给出说明：
Jetty buffers static content for webapps such as HTML files, CSS files, images, etc. If you are using NIO connectors, Jetty uses memory-mapped files to do this. The problem is that on Windows, memory mapping a file causes the file to lock, so that you cannot update or replace the file. Effectively this means that you have to stop Jetty to update a file.
Remedy
Jetty provides a configuration switch in the webdefault.xml file for the DefaultServlet that enables or disables the use of memory-mapped files. If you are running on Windows and are having file-locking problems, you should set this switch to disable memory-mapped file buffers.
The default webdefault.xml file is found in the jetty distribution under the etc/ directory or in the jetty-webapp-${version}.jar artifact at org/eclipse/jetty/webapp/webdefault.xml. Edit the file in the distribution or extract it to a convenient disk location and edit it to change useFileMappedBuffer to false. The easiest option is to simply edit the default file contained in the jetty distribution itself.
<init-param>
<param-name>useFileMappedBuffer</param-name>
<param-value>true</param-value> <!-- change to false -->
</init-param>
Make sure to apply your custom webdefault.xml file to all of your webapps. You can do that by changing the configuration of the Deployment Manager in etc/jetty-deploy.xml.
当jetty已maven嵌入式的形式运行程序时，修改方法：
1、maven本地仓库.m2->\org\eclipse\jetty\jetty-webapp\下找到对于版本的jetty-webapp.jar
2、修改包中文件org\eclipse\jetty\webapp\webdefault.xml内容：
<init-param>
<param-name>useFileMappedBuffer</param-name>
<param-value>false</param-value> <!-- change to false -->
</init-param>
<plugin>
<groupId>org.mortbay.jetty</groupId>
<artifactId>maven-jetty-plugin</artifactId>
<version>6.1.10</version>
<configuration>
<webDefaultXml>src/main/resources/webdefault.xml</webDefaultXml>
</configuration>
</plugin>
参考：
http://www.eclipse.org/jetty/documentation/current/troubleshooting-locked-files-on-windows.html
http://stamen.iteye.com/blog/1933452