今天在做數據加密時mysql相關的一個類報一個只有read的權限，
java.security.AccessControlException: access denied ("java.util.PropertyPermission" "com.mysql.cj.disableAbandonedConnectionCleanup" "read")
解決辦法是：在java11安裝目錄\conf\security\java.policy中添加最后一行配置，重啟一下tomcat
//
// This system policy file grants a set of default permissions to all domains // and can be configured to grant additional permissions to modules and other // code sources. The code source URL scheme for modules linked into a // run-time image is "jrt". //
// For example, to grant permission to read the "foo" property to the module // "com.greetings", the grant entry is: //
// grant codeBase "jrt:/com.greetings" { // permission java.util.PropertyPermission "foo", "read"; // }; //
// default permissions granted to all domains
grant { // allows anyone to listen on dynamic ports
permission java.net.SocketPermission "localhost:0", "listen"; // "standard" properies that can be read by anyone
permission java.util.PropertyPermission "java.version", "read"; permission java.util.PropertyPermission "java.vendor", "read"; permission java.util.PropertyPermission "java.vendor.url", "read"; permission java.util.PropertyPermission "java.class.version", "read"; permission java.util.PropertyPermission "os.name", "read"; permission java.util.PropertyPermission "os.version", "read"; permission java.util.PropertyPermission "os.arch", "read"; permission java.util.PropertyPermission "file.separator", "read"; permission java.util.PropertyPermission "path.separator", "read"; permission java.util.PropertyPermission "line.separator", "read"; permission java.util.PropertyPermission "java.specification.version", "read"; permission java.util.PropertyPermission "java.specification.vendor", "read"; permission java.util.PropertyPermission "java.specification.name", "read"; permission java.util.PropertyPermission "java.vm.specification.version", "read"; permission java.util.PropertyPermission "java.vm.specification.vendor", "read"; permission java.util.PropertyPermission "java.vm.specification.name", "read"; permission java.util.PropertyPermission "java.vm.version", "read"; permission java.util.PropertyPermission "java.vm.vendor", "read"; permission java.util.PropertyPermission "java.vm.name", "read"; permission java.security.AllPermission; };