抛java.lang.NoClassDefFoundError: org.joda.time.ReadablePeriod错误

在进行activiti环境搭建时总是抛出java.lang.NoClassDefFoundError: org.joda.time.ReadablePeriod错误信息，仔细观察该错误信息是NoClassDefFoundError（类没有找到错误），说明是缺少必要的jar文件。

错误信息：

2015-1-31 21:31:06 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

信息: Loading XML bean definitions from class path resource [activiti.cfg.xml]

Exception in thread "main" java.lang.NoClassDefFoundError: org/joda/time/ReadablePeriod

at org.activiti.engine.impl.cfg.ProcessEngineConfigurationImpl.initBusinessCalendarManager(ProcessEngineConfigurationImpl.java:1078)

at org.activiti.engine.impl.cfg.ProcessEngineConfigurationImpl.init(ProcessEngineConfigurationImpl.java:376)

at org.activiti.engine.impl.cfg.ProcessEngineConfigurationImpl.buildProcessEngine(ProcessEngineConfigurationImpl.java:362)

at com.bug315.ActivitiTest01.main(ActivitiTest01.java:11)

Caused by: java.lang.ClassNotFoundException: org.joda.time.ReadablePeriod

at java.net.URLClassLoader$1.run(URLClassLoader.java:202)

at java.security.AccessController.doPrivileged(Native Method)

at java.net.URLClassLoader.findClass(URLClassLoader.java:190)

at java.lang.ClassLoader.loadClass(ClassLoader.java:307)

at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)

at java.lang.ClassLoader.loadClass(ClassLoader.java:248)

... 4 more

解决办法：

将joda-time-2.7-no-tzdb.jar、joda-time-2.7.jar导入到项目的classpath下面即可解决（jar文件你可以到网上下载）。