ssh框架向数据库中存取图片

用ssh像数据库中存储图片。
jsp页面中内容：<form action="userAction.do?method=register" method="post" enctype="multipart/form-data">
    图片：<input type="file" name="pic" /><br> 
    <input type="submit" value="提交" />
</form>在ActioinForm中应该用什么类型接受呢？用Blob的不行。struts不能自动转换。出现以下异常：javax.servlet.ServletException: javax.servlet.ServletException: BeanUtils.populate
org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:286)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:174)
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:77)
root cause javax.servlet.ServletException: BeanUtils.populate
org.apache.struts.util.RequestUtils.populate(RequestUtils.java:475)
org.apache.struts.chain.commands.servlet.PopulateActionForm.populate(PopulateActionForm.java:50)
org.apache.struts.chain.commands.AbstractPopulateActionForm.execute(AbstractPopulateActionForm.java:60)
org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:305)
org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:174)
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:77)
root cause java.lang.IllegalArgumentException: argument type mismatch
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)
org.apache.commons.beanutils.PropertyUtils.setSimpleProperty(PropertyUtils.java:1789)
org.apache.commons.beanutils.PropertyUtils.setNestedProperty(PropertyUtils.java:1684)
org.apache.commons.beanutils.PropertyUtils.setProperty(PropertyUtils.java:1713)
org.apache.commons.beanutils.BeanUtils.setProperty(BeanUtils.java:1019)
org.apache.commons.beanutils.BeanUtils.populate(BeanUtils.java:808)
org.apache.struts.util.RequestUtils.populate(RequestUtils.java:473)
org.apache.struts.chain.commands.servlet.PopulateActionForm.populate(PopulateActionForm.java:50)
org.apache.struts.chain.commands.AbstractPopulateActionForm.execute(AbstractPopulateActionForm.java:60)
org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:305)
org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:174)
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:77)