Java 开发时常见的异常：
`ERROR [org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer] (http-/0.0.0.0:8888-2) HHH000142: Javassist Enhancement failed: com.threeoa.elearning.entity.resource.ThreeResource: java.lang.NoClassDefFoundError: javassist/util/proxy/Proxy
at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.getProxy(JavassistLazyInitializer.java:105) [hibernate-core-4.2.14.SP1-redhat-1.jar:4.2.14.SP1-redhat-1]
at org.hibernate.proxy.pojo.javassist.SerializableProxy.readResolve(SerializableProxy.java:76) [hibernate-core-4.2.14.SP1-redhat-1.jar:4.2.14.SP1-redhat-1]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.7.0_40]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) [rt.jar:1.7.0_40]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [rt.jar:1.7.0_40]
at java.lang.reflect.Method.invoke(Method.java:606) [rt.jar:1.7.0_40]`
原因是*javassist.jar*的版本太旧，*3.16*之前的版本没有`javassist.util.proxy.Proxy` 这个类，替换为新版本既可。