Warning: This jar contains entries whose signer certificate will expire within six months.
如何让它永远不会过期或在更长的时间内过期？
keytool
附录：-validity是keytool的选项.
keytool -genkey -alias sawyer -validity 1234 -dname "…"
创建新密钥后,使用其与jarsigner的唯一别名对JAR进行签名.
jarsigner
