新手求教：ajax获得json数组，但取值显示undefined

[蠢萌蠢萌蓝胖子]

Javascript代码
function as(){
var xmlhttp;
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.open("post","NewFile.jsp",true);
xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
xmlhttp.send("Parameters=8000482699");
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
var json= xmlhttp.responseText;
document.getElementById("test_div").innerHTML=json;
document.getElementById("test_div1").innerHTML=json.length;
document.getElementById("test_div2").innerHTML=json[1].chargeItemName;
}
}
}

Jsp页面代码
List chargeJSONList=new ArrayList();
while(rs.next()){

String CItemName=rs.getString("ITEM_NAME");
String CSpecs=rs.getString("SPECS");
int CItemNum=rs.getInt("QTY");
String CItemUnit=rs.getString("PRICE_UNIT");
String CItemExec=rs.getString("EXEC_DPCD");
int CItemUnitprice=rs.getInt("UNIT_PRICE");
int CTotal=CItemNum*CItemUnitprice;
String CText=rs.getString("TEXT");

Charges charge=new Charges();

charge.setChargeItemName(CItemName);
charge.setChargeSpecs(CSpecs);
charge.setChargeItemNum(CItemNum);
charge.setChargeItemUnit(CItemUnit);
charge.setChargeItemExec(CItemExec);
charge.setChargeItemUnitprice(CItemUnitprice);
charge.setChargeTotal(CTotal);
charge.setChargeText(CText);

chargeJSONList.add(charge);

}
System.out.println(chargeJSONList);
JSONArray jsonarray = JSONArray.fromObject(chargeJSONList);
out.println(jsonarray);
System.out.println(jsonarray);

[天际的海浪]

var json= JSON.parse(xmlhttp.responseText);

[盒仔先生_ujs]

var dataJson = eval(data);

[斯洛文尼亚旅游]

var json=eval('('+ xmlhttp.responseText+')'); document.getElementById("test_div").innerHTML=json; document.getElementById("test_div1").innerHTML=json.length; document.getElementById("test_div2").innerHTML=json[1].chargeItemName;

[文盲老顾]

你这只是获取到json格式的字符串，并没有转换成js对象