ie原生ajax post请求后端获取乱码

//引用json对格式转换
<script src="https://cdnjs.cloudflare.com/ajax/libs/json2/20110223/json2.min.js"></script>

前端测试代码 

function testAjax(){
        var url = '/reins/checkback.do?actionType=testAjax&time=' + new Date().getTime();
        var x = "中国水水水思考卡卡卡啦啦啦股份有限公司";

        var data = "userName="+ escape(escape(x)) +"&checkbacknumber=" + escape(escape('456测试'));
        var xmlhttp ="";
        try {
            xmlhttp=new XMLHttpRequest();
        } catch(e) {
            xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
        }
        xmlhttp.open("post",url,true);
        //文章:https://blog.youkuaiyun.com/bobozai86/article/details/82502954
        xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded;charset=UTF-8");
        xmlhttp.cache=false;
        xmlhttp.send(data);

        xmlhttp.contentType="application/json";
        xmlhttp.onreadystatechange=function() {
            if (xmlhttp.readyState==4 && xmlhttp.status==200) {
                var data = JSON.parse(xmlhttp.responseText);
                // var data = eval("(" + xmlhttp.responseText + ")");
                console.log(data);
                console.log(data.data[0]  + "--" + data.data[1]);
                console.log(data.msg);
                console.log(data.userName);
                alert(data.msg);
            }
        }

    }

后端代码

/**
 * 测试ajax 乱码问题
 * @param request
 * @param response
 * @throws Exception
 */
public void testAjax(HttpServletRequest request, HttpServletResponse response) throws Exception {
    //request.setCharacterEncoding("UTF-8");
    //response.setContentType("text/html;charset=UTF-8");
    response.setContentType("application/json; charset=UTF-8");
    String checkbacknumber = request.getParameter("checkbacknumber");
    String userName= request.getParameter("userName");
    if(StringUtils.isNotBlank(checkbacknumber) && StringUtils.isNotBlank(userName)){
        checkbacknumber = unescape(checkbacknumber);
        userName= unescape(userName);
    }
    ArrayList<String> list = new ArrayList<>();
    list.add("123456");
    list.add("success");
    JSONObject jsonObject=new JSONObject();
    jsonObject.put("msg", "操作成功");
    jsonObject.put("data", list);
    jsonObject.put("userName", userName);
    jsonObject.put("checkbacknumber", checkbacknumber);    
    String data = JSONObject.toJSONString(jsonObject);
    
    PrintWriter out = response.getWriter();
    out.print(data);
    out.flush();
    out.close();
}

主要转换方法 

/**
 * 主要方法unescape
 * @param src
 * @return
 */
public static String unescape(String src) {
    if (src == null) {
        return null;
    }
    StringBuffer tmp = new StringBuffer();
    tmp.ensureCapacity(src.length());
    int lastPos = 0, pos = 0;
    char ch;
    while (lastPos < src.length()) {
        pos = src.indexOf("%", lastPos);
        if (pos == lastPos) {
            if (src.charAt(pos + 1) == 'u') {
                ch = (char) Integer.parseInt(src.substring(pos + 2, pos + 6), 16);
                tmp.append(ch);
                lastPos = pos + 6;
            } else if (src.charAt(pos + 1) == ' '
                    || src.charAt(pos + 1) == ';') {
                tmp.append(src.substring(pos, pos + 1));
                lastPos = pos + 1;
            } else {
                ch = (char) Integer.parseInt(
                        src.substring(pos + 1, pos + 3), 16);
                tmp.append(ch);
                lastPos = pos + 3;
            }
        } else {
            if (pos == -1) {
                tmp.append(src.substring(lastPos));
                lastPos = src.length();
            } else {
                tmp.append(src.substring(lastPos, pos));
                lastPos = pos;
            }
        }
    }
    return tmp.toString();
}

/**
 * 实现escape方法
 * @param src
 * @return
 */
public static String escape(String src) {
    int i;
    char j;
    StringBuffer tmp = new StringBuffer();
    tmp.ensureCapacity(src.length() * 6);
    for (i = 0; i < src.length(); i++) {
        j = src.charAt(i);
        if (Character.isDigit(j) || Character.isLowerCase(j) || Character.isUpperCase(j))
            tmp.append(j);
        else if (j < 256) {
            tmp.append("%");
            if (j < 16){
                tmp.append("0");
            }
            tmp.append(Integer.toString(j, 16));
        } else {
            tmp.append("%u");
            tmp.append(Integer.toString(j, 16));
        }
    }
    return tmp.toString();
}