一般说来,不可避免的Web Service的服务中也会出现异常,举个简单的例子,一个服务接受一个SOAP请求消息,获取有效负载后,进行一个数据库更新操作,而在更新操作过程中发生了SQLException,这个时候就需要告诉客户端(调用Web Service)出现异常了,Axis2将异常封装成为一个AxisFault进行抛出。任何类型的异常Axis2都会对其进行封装,而不管该异常是运行时异常,还是用户自定义异常。
下面是对AxisFault API的一点介绍:
public class AxisFault extends RemoteException
An exception which maps cleanly to a SOAP fault. This is a base class for exceptions which are mapped to faults.
See Also:
SOAP faults contain
1.
A fault string
2.
A fault code
3.
A fault actor
4.
Fault details; an xml tree of fault specific elements
(其中红色的部分为一个AxisFault构造时所必须的部分)
As SOAP1.2 faults are a superset of SOAP1.1 faults, this type holds soap1.2 fault information. When a SOAP1.1 fault is created, spurious information can be discarded. Mapping
SOAP1.2 SOAP1.1
node faultactor
reason(0).text faultstring
faultcode.value faultcode
faultcode.subcode (discarded)
detail detail
role (discarded)
构造函数之一为:
AxisFault
(org.apache.axiom.soap.SOAPFaultCode soapFaultCode, org.apache.axiom.soap.SOAPFaultReason soapFaultReason, org.apache.axiom.soap.SOAPFaultNode soapFaultNode, org.apache.axiom.soap.SOAPFaultRole soapFaultRole, org.apache.axiom.soap.SOAPFaultDetail soapFaultDetail)
由于SOAP 1.1的SOAPFault和SOAP 1.2的SOAPFault的结构不相同,从而导致了如果以1.2的方式构造的SOAPFault不能够被1.1版本的SOAPFault所理解,从而导致异常,异常的内容经常为如下消息:
org.apache.axiom.soap.SOAPProcessingException: Expecting SOAP 1.1 implementation
of SOAP Fault Code. But received some other implementation
一般情况下,SOAPFault是通过SOAPFactory这个工厂类构造的,而SOAP11Factory和SOAP12Factory均继承SOAPFactory,从而对应与两个不同的SOAP协议版本。
可以将SOAP1.1的SOAPFault与SOAP1.2的SOAPFault进行转换,但是比较麻烦。
下面以一个实际的例子来说明有关SOAPFault的一些内容:
1.
建立工程TestFault,如下图所示目录结构:
其中类库使用的是从http://ws.apache.org/axis2下载的最新版本的axis2软件中的类库(笔者写这篇文章时的最新axis2版本为1.1.1)。下载后解压缩,将解压缩后的目录中的lib文件夹下所有的jar文件拷贝到${eclipse.home}/workspace/TestFault/src下,目录结构可能与此不同,只需要将这些jar文件加入到TestFault工程的构建路径中即可。
编写服务器端和客户端的类:
FaultService.java
package l.z.z;
import javax.xml.namespace.QName;
import org.apache.axiom.om.OMAbstractFactory;
import org.apache.axiom.om.OMElement;
import org.apache.axiom.soap.SOAP12Constants;
import org.apache.axiom.soap.SOAPBody;
import org.apache.axiom.soap.SOAPEnvelope;
import org.apache.axiom.soap.SOAPFactory;
import org.apache.axiom.soap.SOAPFault;
import org.apache.axiom.soap.SOAPFaultCode;
import org.apache.axiom.soap.SOAPFaultReason;
import org.apache.axiom.soap.SOAPFaultText;
import org.apache.axiom.soap.SOAPFaultValue;
import org.apache.axis2.AxisFault;
public class FaultService {
public OMElement testFault(OMElement soap) throws AxisFault {
if (soap.getLocalName().equals(“Satan”)) {
throw getAxisFault(“Satan”);
}
throw getAxisFault(“God”);
}
public AxisFault getAxisFault(String message) {
SOAPFactory factory = OMAbstractFactory.getSOAP12Factory();
SOAPEnvelope envelope = factory.createSOAPEnvelope();
SOAPBody body = factory.createSOAPBody(envelope);
SOAPFault soapFault = factory.createSOAPFault(body);
SOAPFaultCode faultCode = factory.createSOAPFaultCode(soapFault);
SOAPFaultReason faultReason =
factory.createSOAPFaultReason(soapFault);
SOAPFaultValue faultValue = factory.createSOAPFaultValue(faultCode);
SOAPFaultText reasonText =
factory.createSOAPFaultText(faultReason);
QName value =
new QName(SOAP12Constants.SOAP_ENVELOPE_NAMESPACE_URI,
SOAP12Constants.SOAP_FAULT_VALUE_SENDER,
SOAP12Constants.SOAP_DEFAULT_NAMESPACE_PREFIX);
faultValue.setText(value);
reasonText.setText(message);
AxisFault axisFault = new AxisFault(soapFault.getCode(), soapFault
.getReason(), null, null, null);
return axisFault;
}
}
TestFaultService.java
package l.z.z.test;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import javax.xml.stream.FactoryConfigurationError;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import org.apache.axiom.om.OMElement;
import org.apache.axiom.om.impl.builder.StAXOMBuilder;
import org.apache.axis2.AxisFault;
import org.apache.axis2.addressing.EndpointReference;
import org.apache.axis2.client.Options;
import org.apache.axis2.client.ServiceClient;
public class TestFaultService {
private static EndpointReference targetEPR = new EndpointReference(
“http://localhost/axis2/services/FaultService”);
public static void main(String[] args) throws FileNotFoundException,
FactoryConfigurationError, XMLStreamException {
OMElement requestSoapMessage =
getSoapRequestMessage(“sample/Satan.xml”);
Options options = new Options();
options.setAction(“urn:testFault”);
options.setTo(targetEPR);
ServiceClient sender = null;
try {
sender = new ServiceClient();
sender.setOptions(options);
sender.sendReceive(requestSoapMessage);
} catch (AxisFault e) {
System.out.println(e.getMessage());
}
}
public static OMElement getSoapRequestMessage(String filePath)
throws FileNotFoundException, XMLStreamException,
FactoryConfigurationError {
XMLStreamReader reader = XMLInputFactory.newInstance()
.createXMLStreamReader(new FileInputStream(filePath));
StAXOMBuilder builder = new StAXOMBuilder(reader);
OMElement requestMessage = builder.getDocumentElement();
return requestMessage;
}
}
然后编写services.xml文件,内容如下:
<
serviceGroup
>
<
service
name
=
“FaultService”
>
<
description
>
This is the service for revoking certificate.
</
description
>
<
parameter
name
=
“ServiceClass”
locked
=
“false”
>
l.z.z.FaultService
</
parameter
>
<
operation
name
=
“testFault”
>
<
messageReceiver
class
=
“org.apache.axis2.receivers.RawXMLINOutMessageReceiver”
/>
<
actionMapping
>
urn:testFault
</
actionMapping
>
</
operation
>
</
service
>
</
serviceGroup
>
由于本文假设读者已经有axis2开发Web Service的基础,所以对于以上类及配置文件不做解释,敬请原谅。
打包成FaultService.aar文件,文件中包含内容如下:
FaultService.aar
—l
—z
—z
—FaultService.class
—META-INF
—MANIFEST.MF
—services.xml
将该aar包放置到${TOMCAT_HOME}\webapps\axis2\WEB-INF\services目录下。
然后选择Services,察看服务是否部署成功,如果已经部署成功,进入下一步骤,否则,请重新检查以上各个步骤。成功后应该如下图所示:
2执行TestFaultService类,可以看到错误消息如下:
(类代码参照上面列出的类)
Transport error 500 . Error Message is <html><head><title>Apache Tomcat/5.5.17 – Error report</title><style><!–H1 {color:white;background-color:#525D76;font-size:22px;} H2 {color:white;background-color:#525D76;font-size:16px;} H3 {color:white;background-color:#525D76;font-size:14px;} BODY {color:black;background-color:white;} B {color:white;background-color:#525D76;} P {background:white;color:black;font-size:12px;}A {color : black;}A.name {color : black;}HR {color : #525D76;}–></style> </head><body><h1>HTTP Status 500 – </h1><HR size=”1″ noshade=”noshade”><p><b>type</b> Exception report</p><p><b>message</b> <u></u></p><p><b>description</b> <u>The server encountered an internal error () that prevented it from fulfilling this request.</u></p><p><b>exception</b>
<pre>org.apache.axiom.soap.SOAPProcessingException: Expecting SOAP 1.1 implementation of SOAP Fault Code. But received some other implementation
org.apache.axiom.soap.impl.llom.soap11.SOAP11FaultImpl.setCode(SOAP11FaultImpl.java:81)
org.apache.axis2.engine.AxisEngine.extractFaultInformationFromMessageContext(
AxisEngine.java:330
)
org.apache.axis2.engine.AxisEngine.createFaultMessageContext(
AxisEngine.java:249
)
org.apache.axis2.transport.http.AxisServlet.handleFault(
AxisServlet.java:317
)
org.apache.axis2.transport.http.AxisServlet.doPost(
AxisServlet.java:277
)
javax.servlet.http.HttpServlet.service(
HttpServlet.java:709
)
javax.servlet.http.HttpServlet.service(
HttpServlet.java:802
)
其中红色的部分是问题的关键,该部分意思是说,客户端期望获得的是一个SOAP 1.1的SOAP Fault Code,但是,我们实际提供的却是一个1.2的实现,所以客户端处理不了,就抛出了异常,而实际出异常的地方那个是红色字体下面的蓝色字体:
SOAP11FaultImpl.setCode时,由于是一个SOAP1.2的SOAP Fault Code,所以不能够处理,只能跑出异常。
而通过使用SOAPMonitor观察到的传入SOAP请求消息是:
注意,Axis2自动的将传入的消息加上一层封装,在传输过程中(没有到达Web Service方法testFault之前)是以这个形式传输的,而Axis2使用的默认的SOAP版本是1.1,所以,不管在FaultService类中构造的AxisFault是SOAP11还是SOAP12,最后都会试图将其转换为SOAP11的格式,而一旦此时出现版本冲突,就会发生异常。
AxisFault还没有返回到客户端,就已经发生了异常(上图中SOAPResponse内容为空)。
解决办法一:
将SOAP12的Fault转换为SOAP11的Fault,这样可以传出SOAP11构造的SOAPFault,但是,名称却和SOAP12一致(比如服务器端异常并不是使用SOAP11的”Server”,而是SOAP12的”Receiver”)。这种办法虽然可以实行,但是一旦客户端是SOAP12怎么办,缺少共通性。
解决办法二:
在构造SOAPFault时进行判断,如果客户端使用的是SOAP12,则使用SOAP12Factory来构造,否则使用SOAP11来构造。
这时,就需要在客户端设置使用的SOAP版本,通过一下方法:
Options
options =
new
Options
();
options.setSoapVersionURI(SOAP12Constants.SOAP_ENVELOPE_NAMESPACE_URI);
这样,就可以设置在传输过程中使用的SOAP封装是SOAP12版本。
这时,通过SOAPMonitor观察到的SOAP请求和响应的消息为:
只所以会有这样的不同是因为通过使用
options.setSoapVersionURI(SOAP12Constants.SOAP_ENVELOPE_NAMESPACE_URI);
设置了将被使用的SOAP的版本。
由于有些客户端可能使用的是不支持SOAP12版本的SOAP协议,所以,有时候需要将SOAP11进行到SOAP12的装换。