验证码不能生成（解决问题有加分）

2017-11-23 16:15:09 ERROR o.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/].[springServlet] - Servlet.service() for servlet [springServlet] in context with path [] threw exception [Handler processing failed; nested exception is java.lang.NoClassDefFoundError: net/sf/ehcache/CacheManager] with root cause
java.lang.ClassNotFoundException: net.sf.ehcache.CacheManager
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1854) ~[catalina.jar:7.0.65]
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1703) ~[catalina.jar:7.0.65]
at com.yanshangtech.common.utils.EHCacheUtil.init(EHCacheUtil.java:37) ~[common-1.0-SNAPSHOT.jar:na]
at com.yanshangtech.common.utils.EHCacheUtil.(EHCacheUtil.java:20) ~[common-1.0-SNAPSHOT.jar:na]
at com.yanshangtech.common.utils.Cache.set(Cache.java:55) ~[common-1.0-SNAPSHOT.jar:na]
at com.yanshangtech.mgt.controller.sys.LoginController.getCaptcha(LoginController.java:52) ~[classes/:na]
at com.yanshangtech.mgt.controller.sys.LoginController$$FastClassBySpringCGLIB$$493e45f2.invoke() ~[classes/:na]
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) ~[spring-core-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:720) ~[spring-aop-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) ~[spring-aop-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:85) ~[spring-aop-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at com.yanshangtech.mgt.common.controller.HasAccess.beforeController(HasAccess.java:48) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.7.0_80]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[na:1.7.0_80]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.7.0_80]
at java.lang.reflect.Method.invoke(Method.java:606) ~[na:1.7.0_80]

第一感觉是路径没写对，明显是图片没加载出来

通过degug看是有类文件没有加载上，但是文件是存在的。