在线等JSP有个<s:propertyvalue='%{jos_messagesBiz.getMessagesByState()}'/>

2011-11-02 15:30:31 [.opensymphony.xwork2.ognl.OgnlValueStack]-[WARN] Caught an exception while evaluating expression 'jos_messagesBiz.getMessagesByState()' against value stack
java.lang.NullPointerException: target is null for method getMessagesByState
at ognl.OgnlRuntime.callMethod(OgnlRuntime.java:1327)
at ognl.ASTMethod.getValueBody(ASTMethod.java:90)
at ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212)
at ognl.SimpleNode.getValue(SimpleNode.java:258)
at ognl.ASTChain.getValueBody(ASTChain.java:141)
at ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212)
at ognl.SimpleNode.getValue(SimpleNode.java:258)
at ognl.Ognl.getValue(Ognl.java:494)
at .opensymphony.xwork2.ognl.OgnlUtil.getValue(OgnlUtil.java:206)
at .opensymphony.xwork2.ognl.OgnlValueStack.findValue(OgnlValueStack.java:276)
at org.apache.struts2.ponents.Property.start(Property.java:141)
at org.apache.struts2.views.jsp.ComponentTagSupport.doStartTag(ComponentTagSupport.java:53)
at org.apache.jsp.WEB_002dINF.administrator.templates.blue.include.header_002dbox_jsp._jspx_meth_s_005fproperty_005f0(header_002dbox_jsp.java:1748)
at org.apache.jsp.WEB_002dINF.administrator.templates.blue.include.header_002dbox_js