问题描述：昨天晚上大厦停电，然后我们把所有的服务都停了，今天早上一大早来了启动的时候发现启动了过了大15s又关闭了。
root@ubuntu:/opt/nexus-2.8.0-05/bin# ./nexus status
****************************************
WARNING - NOT RECOMMENDED TO RUN AS ROOT
****************************************
Nexus OSS is running (31347).
root@ubuntu:/opt/nexus-2.8.0-05/bin# ./nexus status
****************************************
WARNING - NOT RECOMMENDED TO RUN AS ROOT
****************************************
Nexus OSS is not running .
解决思路：
查看日志root@ubuntu:/opt/nexus-2.8.0-05/logs/wrapper.log
发现报错了：
wrapper | Launching a JVM...
jvm 4 | Exception in thread "main" java.lang.UnsupportedClassVersionError: org/sonatype/nexus/bootstrap/jsw/JswLauncher : Unsupported major.minor version 51.0
jvm 4 | at java.lang.ClassLoader.defineClass1(Native Method)
jvm 4 | at java.lang.ClassLoader.defineClass(ClassLoader.java:621)
jvm 4 | at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
jvm 4 | at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
jvm 4 | at java.net.URLClassLoader.access$000(URLClassLoader.java:56)
jvm 4 | at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
jvm 4 | at java.security.AccessController.doPrivileged(Native Method)
jvm 4 | at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
jvm 4 | at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
jvm 4 | at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
jvm 4 | at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
jvm 4 | at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
wrapper | JVM exited while loading the application.
jvm 4 | Could not find the main class: org.sonatype.nexus.bootstrap.jsw.JswLauncher. Program will exit.
这个问题是由于是JDK版本过低，我们环境变量配置的是1.6的版本，所以我就修改了root@ubuntu:/opt/nexus-2.8.0-05/bin/jsw/conf/wrapper.conf 此文件中
#wrapper.java.command=%JAVA_HOME%/bin/java #之前指向环境变量中的JDK1.6
wrapper.java.command=/usr/local/jdk1.7.0_60/bin/java #直接使用的绝对路径
OK了