Java Cryptography Extension (JCE): 放开Java加密算法密钥最大长度16的限制

1. 在官网下载JCE: 

http://www.oracle.com/technetwork/java/javasebusiness/downloads/java-archive-downloads-java-plat-419418.html

2. 解压后，将local_policy.jar，US_export_policy.jar拷贝至JAVA_HOME目录下的 jre/lib/security/目录下，举例：

/usr/java/jdk1.6.0_43/jre/lib/security/

3. 重启tomcat