XML-RPC（）的全称是XML Remote Procedure Call，即XML远程方法调用。是JAVA实现的XML-RPC。
   这种远程过程调用使用http作为传输协议，XML作为传送信息的编码格式。Xml-Rpc的定义尽可能的保持了简单，但同时能够传送、处理、返回复杂的数据结构。
　　XML-RPC是工作在Internet上的远程过程调用协议。一个XML-RPC消息就是一个请求体为xml的http-post请求，被调用的方法在服务器端执行并将执行结果以xml格式编码后返回。
■All primitive Java types are supported, including long, byte, short, and double.
■Calendar objects are supported. In particular, timezone settings, and milliseconds may be sent.
■DOM nodes, or JAXB objects, can be transmitted. So are objects implementing the java.io.Serializable interface.
■Both server and client can operate in a streaming mode, which preserves resources much better than the default mode, which is based on large internal byte arrays.
  概念图如下：
xmlrpc.jpg
和RMI类似，需要服务器类和客户端类。还需要配置web.xml.
服务器类代码片段：
package org.apache.xmlrpc.demo.webserver;
 import java.net.InetAddress;
 import org.apache.xmlrpc.common.TypeConverterFactoryImpl;
 import org.apache.xmlrpc.demo.webserver.proxy.impls.AdderImpl;
 import org.apache.xmlrpc.server.PropertyHandlerMapping;
 import org.apache.xmlrpc.server.XmlRpcServer;
 import org.apache.xmlrpc.server.XmlRpcServerConfigImpl;
 import org.apache.xmlrpc.webserver.WebServer;
 public class Server {
     private static final int port = 8080;
     public static void main(String[] args) throws Exception {
         WebServer webServer = new WebServer(port);      
         XmlRpcServer xmlRpcServer = webServer.getXmlRpcServer();        
         PropertyHandlerMapping phm = new PropertyHandlerMapping();
         /* Load handler definitions from a property file.
          * The property file might look like:
          *   Calculator=org.apache.xmlrpc.demo.Calculator
          *   org.apache.xmlrpc.demo.proxy.Adder=org.apache.xmlrpc.demo.proxy.AdderImpl
          */
         phm.load(Thread.currentThread().getContextClassLoader(),"MyHandlers.properties");
         /* You may also provide the handler classes directly,
          * like this:
          * phm.addHandler("Calculator",
          *     org.apache.xmlrpc.demo.Calculator.class);
          * phm.addHandler(org.apache.xmlrpc.demo.proxy.Adder.class.getName(),
          *     org.apache.xmlrpc.demo.proxy.AdderImpl.class);
          */
         xmlRpcServer.setHandlerMapping(phm);
         XmlRpcServerConfigImpl serverConfig =
             (XmlRpcServerConfigImpl) xmlRpcServer.getConfig();
         serverConfig.setEnabledForExtensions(true);
         serverConfig.setContentLengthOptional(false);
         webServer.start();
     }
 }
web.xml配置片段：
<servlet>
       <servlet-name>XmlRpcServlet</servlet-name>
       <servlet-class>org.apache.xmlrpc.webserver.XmlRpcServlet</servlet-class>
       <init-param>
         <param-name>enabledForExtensions</param-name>
         <param-value>true</param-value>
         <description>
           Sets, whether the servlet supports vendor extensions for XML-RPC.
         </description>
       </init-param>
   </servlet>
   <servlet-mapping>
       <servlet-name>XmlRpcServlet</servlet-name>
       <url-pattern>/xmlrpc</url-pattern>
   </servlet-mapping>
客户端代码片段：
package web.service.xml.rpc;
import java.net.MalformedURLException;
import java.net.URL;
import org.apache.xmlrpc.XmlRpcException;
import org.apache.xmlrpc.client.XmlRpcClient;
import org.apache.xmlrpc.client.XmlRpcClientConfigImpl;
import org.apache.xmlrpc.client.XmlRpcCommonsTransportFactory;
import org.apache.xmlrpc.client.util.ClientFactory;
public class Client {
   public static void main(String[] args) throws Exception {
       // create configuration
       XmlRpcClientConfigImpl config = new XmlRpcClientConfigImpl();
       config.setServerURL(new URL("http://127.0.0.1:8080/WEBXMLRPC"));
       config.setEnabledForExtensions(true);  
       config.setConnectionTimeout(60 * 1000);
       config.setReplyTimeout(60 * 1000);
       XmlRpcClient client = new XmlRpcClient();
       // use Commons HttpClient as transport
       client.setTransportFactory(
           new XmlRpcCommonsTransportFactory(client));
       // set configuration
       client.setConfig(config);
       // make the a regular call
       Object[] params = new Object[]
           { new Integer(2), new Integer(3) };
       Integer result = (Integer) client.execute("calculator_test.add", params);
       System.out.println("2 + 3 = " + result);
   }
}
这里的calculator_test.add关键字是在MyHandlers.properties中配置的。add是方法名。
配置例子：calculator_test=web.service.xml.rpc.Calculator
Calculator类定义如下：
package web.service.xml.rpc;
public class Calculator {
   public int add(int i1, int i2) {
           return i1 + i2;
   }
   public int subtract(int i1, int i2) {
           return i1 - i2;
   }
}