Access restriction: The type FileURLConnection is not accessible due to restrict

问题：
Access restriction: The type FileURLConnection is not accessible due to restriction on required library C:\Program Files\Java\jre6\lib\rt.jar

解决方法：
这个是eclipse设置问题，它默认把这些受访问限制的API设成了ERROR，只要把
Windows-Preferences-Java-Complicer-Errors/Warnings
里面的Deprecated and restricted API中的Forbidden references(access rules)选为Warning就可以编译通过了。