前天做技術交流,有一位同仁針對下面的一段AXIS客戶端代碼提出了這樣的問題:QName qname=new QName("SparePartDetails","SparePartBean");這2個參數是什麼意義?
String endpointURL = "http://localhost:8080/ws/services/SparePartService";
String methodName = "getSparepart";
Service service = new Service();
Call call = (Call) service.createCall();
call.setTargetEndpointAddress(new java.net.URL(endpointURL));
call.setOperationName(new QName("SparePartService", methodName));
call.addParameter("sku", XMLType.XSD_STRING, ParameterMode.IN);
QName qname = new QName("SparePartDetails", "SparePartBean");
Class cls = org.bluebear.ws.advanced.customdatatype.SparePartBean.class;
call.registerTypeMapping(cls, qname, BeanSerializerFactory.class, BeanDeserializerFactory.class);
call.setReturnType(qname);
Object[] params = new Object[] { "222222" };
SparePartBean spBean = (SparePartBean) call.invoke(params);
System.out.println(spBean);
當時有的同仁回答說是根據WSDD中的beanMapping中的定義來確定的。這句話本身沒有錯,可是如果Service是.Net的語言寫的呢?或者Service不是通過AXIS來發布的呢?是否也有WSDD?
<service name="SparePartService" provider="java:RPC"> <parameter name="className" value="org.bluebear.ws.advanced.customdatatype.service001.SparePartService" /> <parameter name="allowMethods" value="getSparePart" /> <beanMapping qname="blueBearNS:SparePartBean" xmlns:blueBearNS="SparePartDetails" languageSpecificType="java:org.bluebear.ws.advanced.customdatatype.SparePartBean" /> </service>
這個問題存留於我的腦海中。對於客戶端而言,只是需要知道如何將返回的SOAP XML 信息轉換成相應的JavaBean就可以了。對於Service而言,只是需要將JavaBean轉換成SOAP XML。所以客戶端的代碼應該和SOAP XML一致。爲此我特地研究了2個方面的問題:
1. QName的Constructor
/**
* <p><code>QName</code> constructor specifying the Namespace URI
* and local part.</p>
*
* <p>If the Namespace URI is <code>null</code>, it is set to
* {@link javax.xml.XMLConstants#NULL_NS_URI
* XMLConstants.NULL_NS_URI}. This value represents no
* explicitly defined Namespace as defined by the <a
* href="http://www.w3.org/TR/REC-xml-names/#ns-qualnames">Namespaces
* in XML</a> specification. This action preserves compatible
* behavior with QName 1.0. Explicitly providing the {@link
* javax.xml.XMLConstants#NULL_NS_URI
* XMLConstants.NULL_NS_URI} value is the preferred coding
* style.</p>
*
* <p>If the local part is <code>null</code> an
* <code>IllegalArgumentException</code> is thrown.
* A local part of "" is allowed to preserve
* compatible behavior with QName 1.0. </p>
*
* <p>When using this constructor, the prefix is set to {@link
* javax.xml.XMLConstants#DEFAULT_NS_PREFIX
* XMLConstants.DEFAULT_NS_PREFIX}.</p>
*
* <p>The Namespace URI is not validated as a
* <a href="http://www.ietf.org/rfc/rfc2396.txt">URI reference</a>.
* The local part is not validated as a
* <a href="http://www.w3.org/TR/REC-xml-names/#NT-NCName">NCName</a>
* as specified in <a href="http://www.w3.org/TR/REC-xml-names/">Namespaces
* in XML</a>.</p>
*
* @param namespaceURI Namespace URI of the <code>QName</code>
* @param localPart local part of the <code>QName</code>
*
* @throws IllegalArgumentException When <code>localPart</code> is
* <code>null</code>
*
* @see #QName(String namespaceURI, String localPart, String
* prefix) QName(String namespaceURI, String localPart, String
* prefix)
*/
public QName(final String namespaceURI, final String localPart) {
this(namespaceURI, localPart, XMLConstants.DEFAULT_NS_PREFIX);
}
從上面的解釋中可以看出,QName的Constructor第一個參數是XML的namespace,第二個參數是該namepace下的一個名字。所 以對於客戶端的代碼而言,QName qname=new QName("SparePartDetails","SparePartBean");所定義的這兩個參數第一個是SparetDetails是 namespace,第二個SparePartBean是JavaBean轉成XML,在XML中的名字。這個問題在Web Service中的WSDL中得到了驗證。
2. WSDL代碼
通過地址:http://localhost:8080/ws/services/SparePartService?wsdl ,即可看到。其中在wsdl:types節點的信息如下:
<wsdl:types> <schema targetNamespace="SparePartDetails" xmlns="http://www.w3.org/2001/XMLSchema"> <import namespace="http://schemas.xmlsoap.org/soap/encoding/"/> <complexType name="SparePartBean"> <sequence> <element name="description" nillable="true" type="soapenc:string"/> <element name="price" type="xsd:float"/> <element name="sku" nillable="true" type="soapenc:string"/> </sequence> </complexType> </schema> </wsdl:types>
其中詳細描述了SparePartDetails namespace下面存在一個因爲SpartPartBean的XML 數據類型。這裏詳細描述了當JavaBean轉成XML的時候,XML的數據結構。
結論:
位於AXIS Service的WSDD中的beanMapping規定了Service
JavaBean轉成XML的時候,XML代碼所必須的的namespace和名字。當客戶端接到SOAP
XML代碼時,必須使用那個namespace和名字才能將相應的XML代碼轉成JavaBean。所以客戶端的代碼的確只是和SOAP XML相關。