Spring的WebServiceTemplate访问WebService的方法及其本质原理

WebService客户端调用的本质就是将SAOP格式的XML通过通信协议发送到WebService的服务器端,然后接收服务器端返回的XML.

本文简单介绍一下如何通过Spring提供的WebServiceTemplate访问Webservice,WebServiceTemplate与调用webservice的客户端已及webservice服务器端示意图如下(图片来源于Spring in Action):

这里以SOAP over HTTP为例,开发步骤如下:

1,在Spring的配置文件中配置WebServiceTemplate,最简单的配置如下:

<bean id="webServiceTemplate" class="org.springframework.ws.client.core.WebServiceTemplate">
    <property name="defaultUri" value="http://localhost:8080/prjCXFWS/services/SimpleServicePort"/>
</bean>	

*这种配置省略了MessageFactory和messageSender的配置,Spring默认会使用SaajSoapMessageFactory和HttpUrlConnectionMessageSender.等同于下面的配置

<bean id="messageFactory" class="org.springframework.ws.soap.saaj.SaajSoapMessageFactory"/>
<bean id="webServiceTemplate" class="org.springframework.ws.client.core.WebServiceTemplate">
    <constructor-arg ref="messageFactory"/>
    <property name="messageSender">
        <bean class="org.springframework.ws.transport.http.HttpUrlConnectionMessageSender"/>
    </property>
    <property name="defaultUri" value="http://localhost:8080/prjCXFWS/services/SimpleServicePort" />
</bean>

还可以使用CommonsHttpMessageSender作为messageSender,它提供了设置timeout,用户名,密码等选项的功能.(需要使用commons-httpclient.jar和commons-codec.jar)
MessageFactory还可以使用AxiomSoapMessageFactory和DomPoxMessageFactory.

<bean id="webServiceTemplate" class="org.springframework.ws.client.core.WebServiceTemplate">
	<property name="messageSender">
	 <bean class="org.springframework.ws.transport.http.CommonsHttpMessageSender">
	  <property name="readTimeout" value="0" />
	 </bean>
	</property>
	<property name="defaultUri" value="http://localhost:8080/prjCXFWS/services/SimpleServicePort" />
</bean>

2,Java调用代码:传输的是SOAP XML.

	private static final String MESSAGE =
        "<queryPeopleByID  xmlns=\"http://test.cxfws.com\">1231ss</queryPeopleByID> ";
	public static void test() {
		ApplicationContext ac = new ClassPathXmlApplicationContext("conf/wsAppcontext.xml");
		WebServiceTemplate simpleService = (WebServiceTemplate) ac.getBean("webServiceTemplate");
		StreamSource source = new StreamSource(new StringReader(MESSAGE));
        StreamResult result = new StreamResult(System.out);        
        simpleService.sendSourceAndReceiveToResult(source, result);
	}

*MESSAGE为需要发送到webservice服务器端的XML payload内容,SOAP body之内的XML内容.

Spring调用Webservice的另一种方法是通过Spring提供的JaxWsPortProxyFactoryBean,示意图如下(图片来源于Spring in Action):

Spring的配置如下:

	<bean id="simpleService"
		class="org.springframework.remoting.jaxws.JaxWsPortProxyFactoryBean">
		<property name="serviceInterface"
			value="com.cxfclient.test.SimpleService" />
		<property name="wsdlDocumentUrl"
			value="http://localhost:8080/prjCXFWS/services/SimpleServicePort?WSDL" />
		<property name="namespaceUri" value="http://test.cxfws.com/" />
		<property name="serviceName" value="SimpleServiceService" />
		<property name="portName" value="SimpleServicePort" />
	</bean>

**这种方式需要用工具通过Webservice 的wsdl文件生成客户端需要的一些Java类,如service的interface,参数类等等(如下面代码中的SimpleService,People类).
Java调用代码如下

ApplicationContext ac = new ClassPathXmlApplicationContext("conf/wsAppcontext.xml");
SimpleService simpleService = (SimpleService) ac.getBean("simpleService");

People people = simpleService.queryPeopleByID("test");
System.out.println(people.getAge() + people.getName() + people.getPid());

关于更多客户端如何调用webservice,参照http://blog.csdn.net/kkdelta/article/details/3987591
对于服务器端,其本质也是接收符合SOAP规范的XML消息,解析XML,返回符合SOAP规范的XML,这里用一个servlet模拟webservice,代码如下:

public class WSSimulator extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)
	throws IOException {
		System.out.println("doGet");
		BufferedReader in = new BufferedReader(new InputStreamReader( request.getInputStream()));
		String str;
        while ((str = in.readLine()) != null) {
            System.out.println(str); ##1
        }
        in.close();
		
		String soapHeader = "<SOAP-ENV:Envelope xmlns:SOAP-ENV=\"http://schemas.xmlsoap.org/soap/envelope/\">" 
			+"<SOAP-ENV:Header/><SOAP-ENV:Body>";
		String soapPayload = "<xxx>yyy</xxx>";
		String soapTail = "</SOAP-ENV:Body></SOAP-ENV:Envelope>";		
		response.getWriter().write(soapHeader + soapPayload + soapTail);  ##2	
	}
	public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
		System.out.println("doPost");
		doGet(request, response);
	}
}

通过WebServiceTemplate将消息发送到这个servlet监听的url,可以更深理解Webservice的本质.
##1 str就是从客户端传输到服务器端的XML.##2将SOAP消息返回给客户端.
更多服务器端webservice的开发请参照http://blog.csdn.net/kkdelta/article/details/3984312