sun.misc.BASE64Encoder找不到jar包的解决方法？ 在MyEclipse中编写Java代码时，用到了BASE64Decoder，import sun.misc.BASE64Decoder；可是Eclipse提示： 　　Access restriction: The type BASE64Decoder is not accessible due to restriction on required library C:\Program 　　files\java\jre6\lib\rt.jar 　　Access restriction : The constructor BASE64Decoder() is not accessible due to restriction on required library C:\Program files\java\jre6\lib\rt.jar