Ajax验证表单信息

Ajax：jsp页面

<script language="javascript">
var xmlHttp;
//创建XMLHttpRequest对象
    function createHttpRequest() {
        if (window.ActiveXObject) {//如果可以取得ActiveXObject
            xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");//Internet Explorer
        } else if (window.XMLHttpRequest) {//如果可以取得XMLHttpRequest
            xmlHttp = new XMLHttpRequest();//Mozilla、Firefox、Safari
        }
    }

    function Check(){
        createHttpRequest();
        //将状态触发器绑定到一个函数
        xmlHttp.onreadystatechange = processor;//处理状态改变函数
    //    xmlHttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");

        var url ="<%=basePath%>servlet/CxywServletAjax?kh="+document.thisform.kh.value+"&mm="+document.thisform.mm.value+"&jylx="+document.thisform.jylx.value+"&jyje="+document.thisform.jyje.value;
        //通过get方法向指定的URL即Servlet对应URL建立服务器的调用
        xmlHttp.open("post", url, true);
        //发送请求
        xmlHttp.send(null);

    }
    function processor() {
        var responseContext;
        //如果响应完成
        if (xmlHttp.readyState == 4) {
            //如果返回成功
            if (xmlHttp.status == 200) {
                //取得响应内容

                responseContext = xmlHttp.responseText;
                //如果检查有效

                switch(parseInt(responseContext)){
                case 0: document.getElementById("khinfo").innerHTML="卡号不存在";
                break;
                case 1:document.getElementById("khinfo").innerHTML="卡号已停用";
                break;
                case 2:document.getElementById("mminfo").innerHTML="密码错误";
                break;
                case 3:document.getElementById("jyjeinfo").innerHTML="余额不足";
                break;
                case 4:alert("交易成功");window.location.href="<%=basePath%>servlet/ZhxxServletSearch";
                break;

                }
            }
        }
    }

servlet：

public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        response.setContentType("text/html");
        request.setCharacterEncoding("utf-8");
        PrintWriter out = response.getWriter();
        CommJdbcManager comm = new CommJdbcManager();
        String jyjeStr = request.getParameter("jyje");
        BigDecimal jyje = new BigDecimal(jyjeStr);
        String mm = request.getParameter("mm");
        String kh = request.getParameter("kh");
        String jylx = request.getParameter("jylx");
        String bz = request.getParameter("bz");
        String date = NewDate.dateFormat();
        String sqlSearch = "select * from p_zhxx where kh='" + kh + "'";
        Zhxx zhxx = null;
        HttpSession session = request.getSession();
        LoginBean operator = (LoginBean) session.getAttribute("user_info");
        String[] sql = new String[2];
        String yhbh = operator.getYhbh();
        try {
            zhxx = (Zhxx) comm.findForObject(sqlSearch, Zhxx.class);
            if (zhxx != null) { // 账户存在

                if (zhxx.getZhzt().equals("0")) {
                    out.println("1");// 停用

                    return;
                }
                if (jylx.equals("2")) { // 取款

                    if (!zhxx.getMm().equals(mm)) {
                        out.println("2");// 密码错误

                        return;
                    }
                    BigDecimal zhye = zhxx.getZhye();
                    if (zhye.compareTo(jyje)< 0) {
                        out.println("3"); // 余额不足

                        return;
                    }

                    sql[0] = "update p_zhxx set ZHYE=ZHYE-'" + jyje
                            + "' where KH='" + kh + "'";
                    sql[1] = "insert into p_jyls(YHBH,ZHBH,JYRQ,JYLX,JYJE,BZ)values('"
                            + yhbh
                            + "','"
                            + zhxx.getZhbh()
                            + "','"
                            + date
                            + "','" + jylx + "','" + jyje + "','" + bz + "')";
                    comm.executeSql(sql);
                } else { // 存款

                    sql[0] = "update p_zhxx set ZHYE=ZHYE+'" + jyjeStr
                            + "' where KH='" + kh + "'";
                    sql[1] = "insert into p_jyls(YHBH,ZHBH,JYRQ,JYLX,JYJE,BZ)values('"
                            + yhbh
                            + "','"
                            + zhxx.getZhbh()
                            + "','"
                            + date
                            + "','" + jylx + "','" + jyje + "','" + bz + "')";
                    comm.executeSql(sql);
                }
                out.println("4");// 成功

                return;
            } else {
                out.println("0");// 卡号不存在

            }
            out.flush();
            out.close();
        } catch (Exception e) {
            // TODO Auto-generated catch block

            e.printStackTrace();
        }

    }

Ajax是在浏览器中运行的，与语言无关。

参考文章：全面剖析XMLHttpRequest对象
http://hi.baidu.com/zhangw19811010/blog/item/8f632d23150bac4e925807fc.html