extjs通过beforeload事件向后台传递参数

listeners : {
       beforeload : function (store, options,eOpts) {
              var process = Ext.getCmp(store.rowId+"process").getValue();
              var new_params = { processNameParam: process  };
              Ext.apply( store.proxy.extraParams , new_params ) ;
       }
}

System.out.println(processNameParam);