spring security2异常

今天在继续我的spring security2时出现了一下异常

java.lang.NoClassDefFoundError: org/apache/commons/codec/binary/Base64
	org.springframework.security.ui.rememberme.AbstractRememberMeServices.decodeCookie(AbstractRememberMeServices.java:150)
	org.springframework.security.ui.rememberme.AbstractRememberMeServices.autoLogin(AbstractRememberMeServices.java:84)
	org.springframework.security.ui.rememberme.RememberMeProcessingFilter.doFilterHttp(RememberMeProcessingFilter.java:74)
	org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
	org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371)
	org.springframework.security.wrapper.SecurityContextHolderAwareRequestFilter.doFilterHttp(SecurityContextHolderAwareRequestFilter.java:91)
	org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
	org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371)
	org.springframework.security.ui.basicauth.BasicProcessingFilter.doFilterHttp(BasicProcessingFilter.java:173)
	org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
	org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371)
	org.springframework.security.ui.AbstractProcessingFilter.doFilterHttp(AbstractProcessingFilter.java:271)
	org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
	org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371)
	org.springframework.security.ui.logout.LogoutFilter.doFilterHttp(LogoutFilter.java:89)
	org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
	org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371)
	org.springframework.security.context.HttpSessionContextIntegrationFilter.doFilterHttp(HttpSessionContextIntegrationFilter.java:235)
	org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
	org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371)
	org.springframework.security.concurrent.ConcurrentSessionFilter.doFilterHttp(ConcurrentSessionFilter.java:99)
	org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
	org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371)
	org.springframework.security.util.FilterChainProxy.doFilter(FilterChainProxy.java:174)
	org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:138)

 java.lang.NoClassDefFoundError这个异常，

解决：在你的项目下加入commons-codec-1.3.jar，好像是编码格式