Flex 的RemoteObject 通讯遇到的问题

今天做了一些flex的测试,是根据”flex第一步”这一本书来做的,主要是在服务端写一个java的类读取数据库数据,然后通过FDS用remotion来做通讯.

java服务端是这样写的:

package tree;
import java.sql.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.Collection;
public class GetUserService {
public static void main(String args[]){
GetUserService db = new GetUserService();
Collection arr = db.getUsers();
System.out.println(arr.toString());
}
//定义函数
public Collection getUsers(){
ArrayList<Map> list = new ArrayList<Map>();
String dbDriver = “com.mysql.jdbc.Driver”;
String dbServer = “localhost”;
String dbName = “walktree”;
String dbUser = “root”;
String dbPass = “feifei”;
String url = “jdbc:mysql://” + dbServer +”/”+dbName+”?user=”+dbUser+”&password=”+dbPass;
try{
Class.forName(dbDriver);
}catch(ClassNotFoundException e){
System.out.println(”连接出错”);
return null;
}
try{
Connection con = DriverManager.getConnection(url);
//创建数据库操作对象
Statement sta = con.createStatement();
String sql = “select * from userinfo”;
ResultSet rs = sta.executeQuery(sql);
Map<String , Object> user;
while(rs.next()){
user = new HashMap<String , Object>();
user.put(”username”, (String)rs.getString(”username”));
user.put(”url”, (String)rs.getString(”url”));
user.put(”email”, (String)rs.getString(”email”));
list.add(user);
//System.out.println(rs.getString(”username”));
}
return list;
}catch(SQLException e){
System.out.println(”无数据”);
return null;
}
}
}

然后flex代码:
<?xml version=”1.0″ encoding=”utf-8″?>
<mx:Application xmlns:mx=”http://www.adobe.com/2006/mxml” layout=”absolute” fontSize=”12″
creationComplete=”init()”>
<mx:Script>
<![CDATA[
import mx.rpc.http.HTTPService;
import mx.rpc.events.ResultEvent;
import mx.rpc.events.FaultEvent;
import flash.events.Event;
import mx.managers.CursorManager;

internal function init():void{
service.getUsers();
}
internal function resultHand(evt:ResultEvent):void{
CursorManager.removeBusyCursor();
myList.labelField = "username";
myList.dataProvider = evt.result;
}
internal function faultHand(evt:FaultEvent):void{
emailTxt.text = "fault"+evt.fault;
trace("fault"+evt.fault);
}
internal function selectHand(evt:Event):void{
var user:Object = myList.selectedItem;
userPanel.title = "详细信息"+user.username;
userTxt.text = user.username;
emailTxt.text = user.email;
urlTxt.text = user.url;
}
]]>
</mx:Script>

<mx:RemoteObject id=”service” fault=”faultHand(event)” showBusyCursor=”true”
destination=”userService” >
<mx:method name=”getUsers” result=”resultHand(event)” />
</mx:RemoteObject>
<mx:Panel x=”10″ y=”10″ width=”156″ height=”286″ layout=”absolute” title=”名册”>
<mx:List id=”myList” x=”0″ y=”0″ width=”100%” height=”244″ change=”selectHand(event)”/>
</mx:Panel>

<mx:Panel x=”183″ y=”10″ width=”276″ height=”286″ layout=”absolute” id=”userPanel”>
<mx:Label x=”10″ y=”10″ text=”Label” id=”userTxt” fontWeight=”bold”/>
<mx:Label x=”12″ y=”38″ text=”Label” id=”emailTxt”/>
<mx:Label x=”12″ y=”66″ text=”Label” id=”urlTxt”/>
</mx:Panel>

</mx:Application>

    最后在tomcat下就是显示不出数据来,于是做了一些测试,在getUsers()函数最后返回一个字符串,如”Hell”,这样在在flex端就可以显示出内容,开始时怎么也想不出问题所在.怀疑是Map的数据与flex的不兼容,于是做了这样一个测试.:

    最后可以通过,flex显示,继续找答案,最后终于找到了.是因为服务端的程序,
Map<String , Object> user;
user = new HashMap<String , Object>();