dwr框架，有个不明白的地方，请高手来看看，代码己贴出。
这里是用DWR框架，实现AJAX写的一段代码，主要代码贴出来了，在JSP文件里红色部分的
KeyWrod.getName(key, callback);callback为什么当参数传进getName函数里，JAVA部分getName函数只有一个参数啊，是用这个框架与后台交互都要这么写么？
<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <title>Struts 2 Ajax Google</title> <script type='text/javascript' src='/struts2ajaxgoogle/dwr/engine.js'></script> <script type='text/javascript' src='/struts2ajaxgoogle/dwr/interface/KeyWrod.js'></script> <script type='text/javascript' src='/struts2ajaxgoogle/dwr/util.js'></script> <script type="text/javascript" src="./jq/jquery-1.6.2.js"></script> <script type="text/javascript"> $(document).ready(function() { $("#search").keyup(function() { var key = $("#search").val(); [color=#FF0000]KeyWrod.getName(key, callback);[/color] }); function callback(date) { var key = ""; for (i = 0; i < date.length; i++) { key = key + date[i][1]+ "</br>"; } $("#result").html("<br>"+key+"</br>"); } });</script> </head> <body> <center> <img style="padding-top: 58px;" src="img/1.jpg"> <br /> <br /> <input type="text" id="search" style="width: 600px; height: 38px; font-size: 20px; font-weight: bold;" /> <input type="button" id="sub" value="Google Search" style="height: 40px;" /> <br /> <div id="result"></div> </center> </body></html>package action;import java.sql.ResultSet;import java.sql.ResultSetMetaData;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import com.opensymphony.xwork2.ActionSupport;import dao.Db;public class KeyAction extends ActionSupport { /** * */ private static final long serialVersionUID = 1L; public List getName(String key) throws Exception { Db db = new Db(); ResultSet rs = db.getKeyWord(key); List list = new ArrayList(); List tempList = new ArrayList(); ResultSetMetaData md = rs.getMetaData(); int columnCount = md.getColumnCount(); while (rs.next()) { for (int i = 1; i <= columnCount; i++) { tempList.add(rs.getObject(i)); } list.add(tempList); } return list; }}