SSI JSON问题

[zhang_zhi_lai]

action：
public class UserAction
{
private User user;

private UserService userService;
@JSON(name="user")
public User getUser()
{
return user;
}

public void setUser(User user)
{
this.user = user;
}



public UserService getUserService()
{
return userService;
}

public void setUserService(UserService userService)
{
this.userService = userService;
}
public String add(){
System.out.println(user.getUsername());
return Action.SUCCESS;
}

}
struts.xml：

<package name="user" namespace="/user" extends="json-default">

<action name="user_add" class="UserAction" method="add">
<result type="json"/>
</action>

</package>


报错：
2012-4-12 11:59:04 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet default threw exception
java.lang.AbstractMethodError: org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.getClientInfo()Ljava/util/Properties;
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.springframework.jdbc.datasource.TransactionAwareDataSourceProxy$TransactionAwareInvocationHandler.invoke(TransactionAwareDataSourceProxy.java:172)
at $Proxy5.getClientInfo(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.googlecode.jsonplugin.JSONWriter.bean(JSONWriter.java:224)
at com.googlecode.jsonplugin.JSONWriter.process(JSONWriter.java:161)
at com.googlecode.jsonplugin.JSONWriter.value(JSONWriter.java:127)
at com.googlecode.jsonplugin.JSONWriter.add(JSONWriter.java:323)
at com.googlecode.jsonplugin.JSONWriter.bean(JSONWriter.java:225)
at com.googlecode.jsonplugin.JSONWriter.process(JSONWriter.java:161)
at com.googlecode.jsonplugin.JSONWriter.value(JSONWriter.java:127)
at com.googlecode.jsonplugin.JSONWriter.add(JSONWriter.java:323)
at com.googlecode.jsonplugin.JSONWriter.bean(JSONWriter.java:225)
at com.googlecode.jsonplugin.JSONWriter.process(JSONWriter.java:161)
at com.googlecode.jsonplugin.JSONWriter.value(JSONWriter.java:127)
at com.googlecode.jsonplugin.JSONWriter.add(JSONWriter.java:323)
at com.googlecode.jsonplugin.JSONWriter.bean(JSONWriter.java:225)
at com.googlecode.jsonplugin.JSONWriter.process(JSONWriter.java:161)
at com.googlecode.jsonplugin.JSONWriter.value(JSONWriter.java:127)
at com.googlecode.jsonplugin.JSONWriter.add(JSONWriter.java:323)
at com.googlecode.jsonplugin.JSONWriter.bean(JSONWriter.java:225)
at com.googlecode.jsonplugin.JSONWriter.process(JSONWriter.java:161)


求解决！！！！！！！！！！！！！

[zhang_zhi_lai]

已解决：
<result type="json">
<!--加<param>-->
<param name="root">user</param>
</result>