Web services AbstractMethodError:gov.nih.nlm.ncbi.www.soap.eutils.eutilservicestub

各位，我是构建Web服务应用程序的新手。我正在使用访问NCBI（国家生物技术信息中心）Web服务API。但是当我尝试访问数据时，我得到了下面的错误

有人知道如何解决这个问题吗

log4j:WARN No appenders could be found for logger (org.apache.axis2.description.AxisOperation).
log4j:WARN Please initialize the log4j system properly.
Exception in thread "main" java.lang.AbstractMethodError: gov.nih.nlm.ncbi.www.soap.eutils.EUtilsServiceStub$EGqueryRequest.serialize(Ljavax/xml/namespace/QName;Ljavax/xml/stream/XMLStreamWriter;)V
    at org.apache.axis2.databinding.ADBDataSource.serialize(ADBDataSource.java:90)
    at org.apache.axiom.om.impl.llom.OMSourcedElementImpl.internalSerialize(OMSourcedElementImpl.java:695)
    at org.apache.axiom.om.impl.util.OMSerializerUtil.serializeChildren(OMSerializerUtil.java:563)
    at org.apache.axiom.om.impl.llom.OMElementImpl.internalSerialize(OMElementImpl.java:874)
    at org.apache.axiom.soap.impl.llom.SOAPEnvelopeImpl.serializeInternally(SOAPEnvelopeImpl.java:283)
    at org.apache.axiom.soap.impl.llom.SOAPEnvelopeImpl.internalSerialize(SOAPEnvelopeImpl.java:245)
    at org.apache.axiom.om.impl.llom.OMSerializableImpl.serializeAndConsume(OMSerializableImpl.java:193)
    at org.apache.axis2.transport.http.SOAPMessageFormatter.writeTo(SOAPMessageFormatter.java:74)
    at org.apache.axis2.transport.http.AxisRequestEntity.writeRequest(AxisRequestEntity.java:84)
    at org.apache.commons.httpclient.methods.EntityEnclosingMethod.writeRequestBody(EntityEnclosingMethod.java:499)
    at org.apache.commons.httpclient.HttpMethodBase.writeRequest(HttpMethodBase.java:2114)
    at org.apache.commons.httpclient.HttpMethodBase.execute(HttpMethodBase.java:1096)
    at org.apache.commons.httpclient.HttpMethodDirector.executeWithRetry(HttpMethodDirector.java:398)
    at org.apache.commons.httpclient.HttpMethodDirector.executeMethod(HttpMethodDirector.java:171)
    at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:397)
    at org.apache.axis2.transport.http.AbstractHTTPSender.executeMethod(AbstractHTTPSender.java:621)
    at org.apache.axis2.transport.http.HTTPSender.sendViaPost(HTTPSender.java:193)
    at org.apache.axis2.transport.http.HTTPSender.send(HTTPSender.java:75)
    at org.apache.axis2.transport.http.CommonsHTTPTransportSender.writeMessageWithCommons(CommonsHTTPTransportSender.java:404)
    at org.apache.axis2.transport.http.CommonsHTTPTransportSender.invoke(CommonsHTTPTransportSender.java:231)
    at org.apache.axis2.engine.AxisEngine.send(AxisEngine.java:443)
    at org.apache.axis2.description.OutInAxisOperationClient.send(OutInAxisOperation.java:406)
    at org.apache.axis2.description.OutInAxisOperationClient.executeImpl(OutInAxisOperation.java:229)
    at org.apache.axis2.client.OperationClient.execute(OperationClient.java:165)
    at gov.nih.nlm.ncbi.www.soap.eutils.EUtilsServiceStub.run_eGquery(EUtilsServiceStub.java:1578)
    at edu.yale.pubmed.service.Client.CallEGQuery(Client.java:26)
    at edu.yale.pubmed.service.Client.main(Client.java:10)

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使用axis2文件夹中生成的文件，它可以成功运行。唯一的结果是它自动实现了EUtilsServiceStub。

我得到了相同的异常。。即使在生成文件之后也是如此。有什么需要帮忙的吗