环境信息：
CentOS release 6.8
tomcat-8.0
JDK1.8
一、启动tomcat
#sh /root/tomcat-8.0/bin/startup.sh
#tailf /root/tomcat-8.0/logs/catalina.out
26-Aug-2017 12:58:31.661 INFO [main] org.apache.tomcat.util.net.NioSelectorPool.getSharedSelector Using a shared selector for servlet write/read26-Aug-2017 12:58:31.662 INFO [main] org.apache.catalina.startup.Catalina.load Initialization processed in 680 ms26-Aug-2017 12:58:31.685 INFO [main] org.apache.catalina.core.StandardService.startInternal Starting service Catalina26-Aug-2017 12:58:31.685 INFO [main] org.apache.catalina.core.StandardEngine.startInternal Starting Servlet Engine: Apache Tomcat/8.0.3226-Aug-2017 12:58:31.695 INFO [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory /root/tomcat-8.0/webapps/ROOT26-Aug-2017 12:58:36.184 INFO [localhost-startStop-1] org.apache.jasper.servlet.TldScanner.scanJars At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.26-Aug-2017 12:58:37.895 INFO [localhost-startStop-1] java.util.prefs.FileSystemPreferences$2.run Created system preferences directory in java.home.26-Aug-2017 12:58:37.897 INFO [localhost-startStop-1] java.util.prefs.FileSystemPreferences$1.run Created user preferences directory.26-Aug-2017 12:58:37.907 WARNING [localhost-startStop-1] java.util.prefs.FileSystemPreferences$6.run Prefs file removed in background /root/.java/.userPrefs/prefs.xml26-Aug-2017 12:58:37.908 WARNING [localhost-startStop-1] java.util.prefs.FileSystemPreferences$6.run Prefs file removed in background /root/jdk-1.8/jre/.systemPrefs/prefs.xml
... ...
等待tomcat启动的过程是煎熬的，足足5/6分钟，在不抱希望的情况下它居然又启动完成了......
有两种解决办法：
1）在Tomcat环境中解决
在catalina.sh中加入这么一行：-Djava.security.egd=file:/dev/./urandom
例如：
JAVA_OPTS="-server -Xms2048m -Xmx4096m -XX:PermSize=256M -XX:MaxPermSize=512m -Djava.security.egd=file:/dev/./urandom"
2）在JVM环境中解决
修改$JAVA_PATH/jre/lib/security/java.securitysecurerandom.source=file:/dev/urandom
替换成
securerandom.source=file:/dev/./urandom