maven jetty 热部署 Files are locked on Windows and can't be replaced

在windows操作系统用jetty maven plugin运行jetty:run命令，修改静态html等资源后不能保存，出现文件被锁问题。

原因：maven jetty plugin 的默认webdefault.xml中的default servlet的初始参数useFileMappedBuffer值为true。

Jetty buffers static content for webapps such as html files, css files, images etc and uses memory mapped files to do this if the NIO connectors are being used. The problem is that on Windows, memory mapping a file causes the file to be locked, so that the file cannot be updated or replaced. See Sun bug: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4715154. This means that effectively you have to stop Jetty in order to update a file.

<servlet>    <servlet-name>default</servlet-name>    <servlet-class>org.eclipse.jetty.servlet.DefaultServlet</servlet-class>    <init-param>      <param-name>aliases</param-name>      <param-value>false</param-value>    </init-param>    <init-param>      <param-name>acceptRanges</param-name>      <param-value>true</param-value>    </init-param>    <init-param>      <param-name>dirAllowed</param-name>      <param-value>true</param-value>    </init-param>    <init-param>      <param-name>welcomeServlets</param-name>      <param-value>false</param-value>    </init-param>    <init-param>      <param-name>redirectWelcome</param-name>      <param-value>false</param-value>    </init-param>    <init-param>      <param-name>maxCacheSize</param-name>      <param-value>256000000</param-value>    </init-param>    <init-param>      <param-name>maxCachedFileSize</param-name>      <param-value>200000000</param-value>    </init-param>    <init-param>      <param-name>maxCachedFiles</param-name>      <param-value>2048</param-value>    </init-param>    <init-param>      <param-name>gzip</param-name>      <param-value>false</param-value>    </init-param>    <init-param>      <param-name>etags</param-name>      <param-value>false</param-value>    </init-param>    <init-param>      <param-name>useFileMappedBuffer</param-name>      <param-value>true</param-value>    </init-param>    <!--    <init-param>      <param-name>resourceCache</param-name>      <param-value>resourceCache</param-value>    </init-param>    -->    <!--    <init-param>      <param-name>cacheControl</param-name>      <param-value>max-age=3600,public</param-value>    </init-param>    -->    <load-on-startup>0</load-on-startup>  </servlet>

  <servlet-mapping>    <servlet-name>default</servlet-name>    <url-pattern>/</url-pattern>  </servlet-mapping>

解决：

1.可以拷贝一份webdefault.xml到工程的resources目录修改参数useFileMappedBuffer为false。并在plugin的configuration配置如下参数

<plugin>            ...            <artifactId>jetty-maven-plugin</artifactId>            <configuration>                <webAppConfig>                  ...                  <defaultsDescriptor>/my/path/to/webdefault.xml</defaultsDescriptor>                </webAppConfig>            </configuration></plugin>

2.

在web.xml 添加如下参数

jetty plugin groupId为org.eclipse.jetty 添加

<context-param>
    <param-name>org.eclipse.jetty.servlet.Default.useFileMappedBuffer</param-name>
    <param-value>false</param-value>
</context-param>
====================================================================================

jetty plugin groupId为org.mortbay.jetty 添加

<context-param>
    <param-name>org.mortbay.jetty.servlet.Default.useFileMappedBuffer</param-name>
    <param-value>false</param-value>
</context-param>

参考：

http://www.eclipse.org/jetty/documentation/current/troubleshooting-locked-files-on-windows.html
http://docs.codehaus.org/display/JETTY/Files+locked+on+Windows