与tomcat类似，直接拷贝war到webapps目录即可，不同的是解压文件不会存放到webapps下。
需要做一些额外配置，才能找到正确解压目录
参考资料：http://dev.eclipse.org/mhonarc/lists/jetty-users/msg01998.html
Q: How to change the extracted directory?
A: You have few choices.
1) Specify your own java.io.tmpdir java system property location for jetty to use.
$ java -Djava.io.tmpdir=/path/to/my/new/temp/ -jar start.jar
2) Create a "work" directory under the ${jetty.home} path (whereever that is).
That will cause Jetty to use that work directory instead of whatever the java.io.tmpdir property is set to.
3) Specify the tempDir attribute on the WebAppProvider deployments.
Only valid for war file deployment scenarios, NOT valid for context based deployment.
If you have etc/jetty-webapps.xml in your start.ini you have war file deployments enabled.
Edit the ${jetty.home}/etc/jetty-webapps.xml file and add 1 more attribute on the WebAppProvider.
<Set name="tempDir">/path/to/my/preferred/temp/dir/for/all/webapps</Set>
4) Set the tempDirectory attribute on the WebAppContext with context based deployments.
NOT valid for war file deployment scenarios.
If you have etc/jetty-context.xml in your start.ini you have context based deployments enabled.
Edit the ${jetty.home}/contexts/myapp.xml and add the tempDirectory attribute on the WebAppContext.
<Set name="tempDirectory">/path/to/my/preferred/temp/dir/for/this/context</Set>