java转json对象

 Ext.Ajax.request({
            url : ctxpath + '/ShopManager/LoadPlanListGrid',
            params : {},
            method : 'post',
            callback : function(options, success, response) {
                var json = Ext.JSON.decode(response.responseText);
                var store = Ext.create('Ext.data.Store', {
                            fields : json.fields,
                            data : json.datas
                        });
                Ext.getCmp("configGrid").reconfigure(store, json.columns);
            }
        });

问题补充：{ 
  "columns":[ 
              {"align":"center","dataIndex":"goods_name","sortable":true,"text":"商品名称","width":200}, 
      {"align":"center","dataIndex":"goods_type","sortable":true,"text":"存货类别","width":200}, 
      {"align":"center","dataIndex":"goods_supply_factory","sortable":true,"text":"供应商","width":200}, 
      {"align":"center","dataIndex":"goods_factory","sortable":true,"text":"生产厂家","width":200}, 
      {"align":"center","dataIndex":"goods_spec","sortable":true,"text":"规格","width":200}, 
      {"align":"center","dataIndex":"goods_unit","sortable":true,"text":"计量单位","width":200}, 
      {"align":"center","dataIndex":"goods_price_first","sortable":true,"text":"采购价格","width":200}, 
      {"align":"center","dataIndex":"goods_price_last","sortable":true,"text":"结算价格","width":200}, 
      {"align":"center","dataIndex":"goods_price_first_all","sortable":true,"text":"计划采购金额","width":200}, 
      {"align":"center","dataIndex":"stock_plan_first_all","sortable":true,"text":"计划合计","width":200}, 
      {"align":"center","dataIndex":"goods_price_last_all","sortable":true,"text":"实际采购金额","width":200}, 
      {"align":"center","dataIndex":"stock_plan_last_all","sortable":true,"text":"实际合计","width":200}, 
      {"columns":[ 
                  {"align":"center","dataIndex":"hn_jinchuan#stock_plan_first","sortable":true,"text":"计划","width":100}, 
  {"align":"center","dataIndex":"hn_jinchuan#stock_plan_last","sortable":true,"text":"实际","width":100}, 
  {"align":"center","dataIndex":"hn_jinchuan#goods_price_last_all","sortable":true,"text":"金额","width":100}],"text":"金川猪场"} 
    ], 

   "condition":null, 
   
   "datas":"[ 
             {"goods_unit":"包", 
      "stock_plan_last_all":"115.0", 
      "hn_jinchuan#stock_plan_first":"115", 
      "goods_factory":"勃林格殷格翰美国子公司（密苏里州）", 
      "goods_price_first_all":"149500.0", 
      "goods_price_last":"1300.00", 
      "goods_name":"民星六甲氧散1kg×10包", 
      "goods_supply_factory":"", 
      "goods_price_last_all":"149500.0", 
      "stock_plan_first_all":"115.0", 
      "goods_price_first":"1300.00", 
      "hn_jinchuan#stock_plan_last":"115", 
      "goods_type":"粉散剂", 
      "goods_spec":"1kg×10包", 
      "hn_jinchuan#goods_price_last_all":"149500.0"}]", 

   "fields":[ 
             {"mapping":"goods_name","name":"goods_name","type":"String"}, 
     {"mapping":"goods_type","name":"goods_type","type":"String"}, 
     {"mapping":"goods_supply_factory","name":"goods_supply_factory","type":"String"}, 
     {"mapping":"goods_factory","name":"goods_factory","type":"String"}, 
     {"mapping":"goods_spec","name":"goods_spec","type":"String"}, 
     {"mapping":"goods_unit","name":"goods_unit","type":"String"}, 
     {"mapping":"goods_price_first","name":"goods_price_first","type":"String"}, 
     {"mapping":"goods_price_last","name":"goods_price_last","type":"String"}, 
     {"mapping":"goods_price_first_all","name":"goods_price_first_all","type":"String"}, 
     {"mapping":"stock_plan_first_all","name":"stock_plan_first_all","type":"String"}, 
     {"mapping":"goods_price_last_all","name":"goods_price_last_all","type":"String"}, 
     {"mapping":"stock_plan_last_all","name":"stock_plan_last_all","type":"String"}, 
     {"mapping":"hn_jinchuan#stock_plan_first","name":"hn_jinchuan#stock_plan_first","type":"String"},
     {"mapping":"hn_jinchuan#stock_plan_last","name":"hn_jinchuan#stock_plan_last","type":"String"},
     {"mapping":"hn_jinchuan#goods_price_last_all","name":"hn_jinchuan#goods_price_last_all","type":"String"}
    ], 

   "submitTime":"2013-08" 
   
}

　　当json.datas的格式是这样的：["{"key1":"value1"}","{"key2":"value2"}"] 
应该将数据改为：[{"key1":"value1"},{"key2":"value2"}]这种格式， 不然取不到key1,key2及其对应的值。