三、开发一个简单的RESTful Web Service
1. 在Eclipse中创建一个Dynamic Web Project作为Web Service的宿主:
选择File->New->Dynamic Web Project
输入Project Name为HelloRestfulService
2. 右击Java Resources: src,新建一个class,其中package、Name、Interfaces如下设置:
3. 加入如下代码:
package com.ibm.wasce.samples.jaxws.rest;
import java.io.ByteArrayInputStream;
import javax.annotation.Resource;
import javax.servlet.ServletRequest;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Source;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamSource;
import javax.xml.ws.BindingType;
import javax.xml.ws.Provider;
import javax.xml.ws.WebServiceContext;
import javax.xml.ws.WebServiceProvider;
import javax.xml.ws.handler.MessageContext;
import javax.xml.ws.http.HTTPBinding;
import javax.xml.ws.http.HTTPException;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
@WebServiceProvider
@BindingType (value = HTTPBinding. HTTP_BINDING )
public class HelloWorld implements Provider<Source> {
@Resource
protected WebServiceContext wsContext ;
public Source invoke(Source source) {
try {
String targetName = null ;
if (source == null ) {
//Get: Getting input from query string
MessageContext mc = wsContext .getMessageContext();
String query = (String) mc.get(MessageContext. QUERY_STRING );
System. out .println( "Query String = " + query);
ServletRequest req = (ServletRequest) mc.get(MessageContext. SERVLET_REQUEST );
targetName = req.getParameter( "target" );
} else {
//POST: Getting input from input box
Node n = null ;
if (source instanceof DOMSource) {
n = ((DOMSource) source).getNode();
} else if (source instanceof StreamSource) {
StreamSource streamSource = (StreamSource) source;
DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
InputSource inputSource = null ;
if (streamSource.getInputStream() != null ) {
inputSource = new InputSource(streamSource.getInputStream());
} else if (streamSource.getReader() != null ) {
inputSource = new InputSource(streamSource.getReader());
}
n = builder.parse(inputSource);
} else {
throw new RuntimeException( "Unsupported source: " + source);
}
NodeList children = n.getChildNodes();
for ( int i = 0; i < children.getLength(); i++) {
Node child = children.item(i);
if (child.getNodeName().equals( "people" )) {
targetName = child.getAttributes().getNamedItem( "target" ).getNodeValue();
break ;
}
}
}
String body = "<ns:return xmlns:ns=\"http://rest.jaxws.samples.wasce.ibm.com\">"
+ "<ns:HelloWorldResponse>" + this .sayHello(targetName) + "</ns:HelloWorldResponse>"
+ "</ns:return>" ;
return new StreamSource( new ByteArrayInputStream(body.getBytes()));
} catch (Exception e) {
e.printStackTrace();
throw new HTTPException(500);
}
}
private String sayHello(String target){
return "Hello " + target;
}
}
让我们看一看代码中的几个关键点:
a) @WebServiceProvider 表明这个Web Service实现了Provider接口,可以对XML消息进行完全的处理。
b) Provider 是这类Web Service都要实现的接口,它只有一个方法需要实现,即:
public abstractjava.lang.Object invoke(java.lang.Object arg0);
c) Source 是交换信息的载体:
当Source对象为空时,表示是一个GET Request。因为这种情况下,所有信息是被拼成一个URI的参数,并传到这个URI对应的Web Service。
否则,是一个POST Request,其内容会包括在一个Source对象内;
另外,Response的内容也要放到一个Source对象内。
4. 编写web.xml
为了使我们前面编写的Web Service能够成功部署到WAS CE中,我们需要将如下内容加入到web.xml中:
<servlet>
<servlet-name>Hello</servlet-name>
<servlet-class>com.ibm.wasce.samples.jaxws.rest.HelloWorld</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Hello</servlet-name>
<url-pattern>/Hello</url-pattern>
</servlet-mapping>
注意,这里只是借用了<servlet>和<servlet-mapping>标签来帮助暴露Web Service,并不是真是要求这个Web Service必须要实现HttpServlet接口。
5. 部署,运行并测试这个Web Service
右击这个HelloRestfulService工程,选择Run As -> Run on Server,会将其部署到WAS CE中,当Status栏变为Synchronized时,在Console中会有类似如下信息显示:
通过访问如下地址,测试使用GET方式调用RESTful Web Service返回的结果: