14.2 原理

14.2  原理

JSON-RPC共分为两端、三部分。

两端：是指Web服务器端的JSON-RPC Java框架服务程序，和客户端的浏览器轻量级AJAX框架服务程序。
三部分：指Web服务器端的服务程序分为注册RPC反射（Java术语，请读者参阅http://zhidao.baidu.com/question/17425148.html?fr=qrl3）服务对象和Servlet服务程序，客户端浏览器服务的AJAX JavaSCript程序。如图14-1所示。

图14-1  JSON-RPC原理图

其中图14-1中4向2不发送任何数据的时候，服务器端返回所有被注册Java对象的JSON字符串格式：{"result":[{"methods":["getMyList","getMyMap","hashCode","toString"],"lst":{"methods":["add","indexOf","clone","clear","contains","isEmpty","lastIndexOf","addAll","get","size","toArray","remove","set","ensureCapacity","trimToSize","hashCode","iterator","subList","listIterator","toString","containsAll","removeAll","retainAll"],id:"1064745629"},"szName":"\u6211\u662fjcore.jsonrpc.test.Test\u7684\u6210\u5458szName","age":30,name:"myTest",id:"2347637"},{"methods":["getRequest","setRequest","Translate","Click","hashCode","toString"],name:"myTrs",id:"30283254"}]}
可以从上面看出，被注册对象的public属性和方法都已经被格式化为JSON的表示形式。图14-1中4接收到上面的数据后进行解析和绑定到JavaScript对象var oRpc = new JsonRpcClient()上,这时候就可以使用对象的方法了，如下所示：

var szStr = oRpc.myTrs.Translate(“中国”, “zh”, “en”); // 翻译为英语

这时候向服务器发送的数据格式为：

{"method”:”Translate”,id:”30283254”,"params”:[“中国”,“zh”,“en”]} 

服务器端将返回：China。Translate方法的返回结果只是一般的字符串了，那么前面描述的oList = oRpc.getMyList()将会返回什么样格式的数据呢？请看下面：

{"methods":["add","indexOf","clone","clear","contains","isEmpty","lastIndexOf","addAll","get","size","toArray","remove","set","ensureCapacity","trimToSize","hashCode","iterator","subList","listIterator","toString","containsAll","removeAll","retainAll"],id:"1064745629"}
同样，你会看到java.util.List对象的相关方法的一个清单描述，这时候你就可以使用oList.get(3)来获得对象A了。