ExtJS中回调DWR方法

最近开始学习ExtJS，发现其与DWR之间还是存在不太协调之处，其实我的需求很简单：就是在Ext的store对象能调用DWR暴露的接口，并将数据写的STORE中。于是GOOGLE了一下，发现以下东东：  

Ext.data.DWRProxy = function(fn)...{
    Ext.data.DWRProxy.superclass.constructor.call(this);
    this.fn = fn;
};
Ext.extend(Ext.data.DWRProxy, Ext.data.DataProxy, ...{  
    load : function(params, reader, callback, scope, arg)...{
        params = params || ...{};       
        if(this.fireEvent("beforeload", this, params) !== false)
        ...{
            var proxy=this;
            this.fn(params,function(ret)...{
                var result;
                try 
                ...{    
                    
                    var o = eval("("+ret+")");
                    //alert(o);
                    result = reader.readRecords(o);
                }catch(e)
                ...{
                    this.fireEvent("loadexception", this, arg, null, e);
                    callback.call(scope, null, arg, false);
                    return;
                }
                //alert('call back');
                callback.call(scope, result, arg, true);
                         });
          
        }   
    }

});

但调用时发现根本无法调用。

调用代码如下：

var grid;
Ext.onReady(function(){
    
    grid = getRegion();
    
});


function getRegion()
{        
    var store=new Ext.data.DWRStore({        
          id:"code",
          fn:ServerParserImpl.test,  
          fields:[{name:'year'},
              {name:'code'},{name:'name'},
              {name:'province_shortname'},
              {name:'owner'},
              {name:'level'},{name:'area'},
              {name:'pepole'},
              {name:'place'},{name:'postcode'},
              {name:'recordStatus'}]
                
          });
          
    var cm=new Ext.grid.ColumnModel([
        new Ext.grid.RowNumberer({width:50}),
        {header: "年",dataIndex:"year",sortable:true},
        {header: "行政区编码",dataIndex:"code",sortable:true},
        {header: "行政区名称",dataIndex:"name",sortable:true},
        {header: "所属省份简称",dataIndex:"province_shortname",sortable:true},
        {header: "所属省份",dataIndex:"owner",sortable:true},
        {header: "级别",dataIndex:"level",sortable:true},
        {header: "面积",dataIndex:"area",sortable:true},
        {header: "人口",dataIndex:"pepole",sortable:true},
        {header: "地区",dataIndex:"place",sortable:true},
        {header: "邮编",dataIndex:"postcode",sortable:true},
        {header: "记录状态",dataIndex:"recordStatus"}        
        ]);    

    var grid=new Ext.grid.GridPanel({      
        store:store,
          cm:cm, 
        loadMask: {msg:'正在加载数据，请稍候……'},
        frame:true,        
        tbar:[{pressed:true,text:'查询',handler:query},
        {pressed:true,text:'增加',handler:add},
        {pressed:true,text:'删除',handler:remove},
        {pressed:true,text:'修改',handler:edit},
        {pressed:true,text:'保存',handler:save}]
      });     

     new Ext.Viewport({layout:"fit",items:grid});
     store.load({params:["str1",[{year:2008,code:'1000000'}],56.90]});
     return grid;
 }

经过多方分析，需要修改DWRProxy中的load，修改如下：

Ext.data.DWRProxy = function(fn){
    Ext.data.DWRProxy.superclass.constructor.call(this);
    this.fn = fn;
};
Ext.extend(Ext.data.DWRProxy, Ext.data.DataProxy, {  
    load : function(params, reader, callback, scope, arg){
        params = params || {};       
        if(this.fireEvent("beforeload", this, params) !== false)
        {
            var proxy=this;
            //dwr回调函数
              dwrcallback = function(ret){
                var result;
                try 
                {                    
                    var o = eval("("+ret+")");
                    result = reader.readRecords(o);
                }catch(e)
                {
                    this.fireEvent("loadexception", this, arg, null, e);
                    callback.call(scope, null, arg, false);
                    return;
                }
                callback.call(scope, result, arg, true);
            }
            //需要将参数加入到调用参数
            var callParams = new Array();
            for(var i=0; i<params.length;++i)
            {
                callParams.push(params[i]);
            }
            //将回调函数加入的参数数组
            callParams.push(dwrcallback);
              this.fn.apply(this, callParams);
        }   
    }

});

现将所有与DWR相关的EXTJS类贴出，希望能给与我一样的初学者一些帮助：

Ext.data.DWRProxy = function(fn){
    Ext.data.DWRProxy.superclass.constructor.call(this);
    this.fn = fn;
};
Ext.extend(Ext.data.DWRProxy, Ext.data.DataProxy, {  
    load : function(params, reader, callback, scope, arg){
        params = params || {};       
        if(this.fireEvent("beforeload", this, params) !== false)
        {
            var proxy=this;
            //dwr回调函数
              dwrcallback = function(ret){
                var result;
                try 
                {                    
                    var o = eval("("+ret+")");
                    result = reader.readRecords(o);
                }catch(e)
                {
                    this.fireEvent("loadexception", this, arg, null, e);
                    callback.call(scope, null, arg, false);
                    return;
                }
                callback.call(scope, result, arg, true);
            }
            //需要将参数加入到调用参数
            var callParams = new Array();
            for(var i=0; i<params.length;++i)
            {
                callParams.push(params[i]);
            }
            //将回调函数加入的参数数组
            callParams.push(dwrcallback);
              this.fn.apply(this, callParams);
        }   
    }

});

/**
* Ext.data.DWRStore实现对DWR调用后返回的记录进行存储
*    当调用的DWR方法返回的是JSON对象时，使用此存储类进行管理
*/
Ext.data.DWRStore = function(c){
    Ext.data.DWRStore.superclass.constructor.call(this, Ext.apply(c, {
        proxy: c.fn ? new Ext.data.DWRProxy(c.fn): undefined,
        reader: c.reader ? c.reader : new Ext.data.JsonReader(c, c.fields)
    }));
};
Ext.extend(Ext.data.DWRStore, Ext.data.Store);

 后台JAVA方法定义：public String test(String str1,List lst,Double dbvalue){return "[{year:2008}]"}