dom4j:Adding text to an XML document must not be null

背景：

dom4j:Adding text to an XML document must not be null

在使用dom4j组装xml时，出现如下错误：

org.apache.cxf.interceptor.Fault: Adding text to an XML document must not be null
 at org.apache.cxf.service.invoker.AbstractInvoker.createFault(AbstractInvoker.java:162)
 at org.apache.cxf.jaxws.AbstractJAXWSMethodInvoker.createFault(AbstractJAXWSMethodInvoker.java:213)
 at org.apache.cxf.service.invoker.AbstractInvoker.invoke(AbstractInvoker.java:128)
 at org.apache.cxf.jaxws.AbstractJAXWSMethodInvoker.invoke(AbstractJAXWSMethodInvoker.java:178)
 at org.apache.cxf.jaxws.JAXWSMethodInvoker.invoke(JAXWSMethodInvoker.java:68)
 at org.apache.cxf.service.invoker.AbstractInvoker.invoke(AbstractInvoker.java:75)
 at org.apache.cxf.interceptor.ServiceInvokerInterceptor$1.run(ServiceInvokerInterceptor.java:58)
 at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
 at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
 at java.util.concurrent.FutureTask.run(FutureTask.java:138)
 at org.apache.cxf.workqueue.SynchronousExecutor.execute(SynchronousExecutor.java:37)
 at org.apache.cxf.interceptor.ServiceInvokerInterceptor.handleMessage(ServiceInvokerInterceptor.java:107)
 at org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:272)
 at org.apache.cxf.transport.ChainInitiationObserver.onMessage(ChainInitiationObserver.java:121)
 at org.apache.cxf.transport.http.AbstractHTTPDestination.invoke(AbstractHTTPDestination.java:239)
 at org.apache.cxf.transport.servlet.ServletController.invokeDestination(ServletController.java:248)
 at org.apache.cxf.transport.servlet.ServletController.invoke(ServletController.java:222)
 at org.apache.cxf.transport.servlet.ServletController.invoke(ServletController.java:153)
 at org.apache.cxf.transport.servlet.CXFNonSpringServlet.invoke(CXFNonSpringServlet.java:167)
 at org.apache.cxf.transport.servlet.AbstractHTTPServlet.handleRequest(AbstractHTTPServlet.java:286)
 at org.apache.cxf.transport.servlet.AbstractHTTPServlet.doPost(AbstractHTTPServlet.java:206)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
 at org.apache.cxf.transport.servlet.AbstractHTTPServlet.service(AbstractHTTPServlet.java:262)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
 at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
 at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
 at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
 at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.IllegalArgumentException: Adding text to an XML document must not be null
 at org.dom4j.DocumentFactory.createText(DocumentFactory.java:174)
 at org.dom4j.tree.AbstractElement.addText(AbstractElement.java:899)
 at org.dom4j.tree.AbstractElement.setText(AbstractElement.java:1120)
 at com.dyst.tippe.util.XMLUtils.genQueryResponseXmlFor04C01(XMLUtils.java:132)
 at com.dyst.tippe.service.impl.PunishProxyServiceHelper.handle(PunishProxyServiceHelper.java:95)
 at com.dyst.tippe.service.impl.PunishProxyServiceImpl.queryObjectOut(PunishProxyServiceImpl.java:23)
 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.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:318)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
 at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
 at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:90)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
 at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
 at $Proxy12.queryObjectOut(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 org.apache.cxf.service.invoker.AbstractInvoker.performInvocation(AbstractInvoker.java:180)
 at org.apache.cxf.service.invoker.AbstractInvoker.invoke(AbstractInvoker.java:96)
 ... 32 more

解决：每一个element的test值都需要判断，建议写成方法
 
StringUtil类：