javax注意事项

        <script type="text/javascript">
            var req;
            var target;
            //初始化
            function initRequest()
            {
            if (window.XMLHttpRequest) {
            req = new XMLHttpRequest();
            } else if (window.ActiveXObject) {
            req = new ActiveXObject("Microsoft.XMLHTTP");
            }
            }
           
            function getCharacterCount() {
            //未实例化时,下次调用时不再实例化对象。
            if (!target) target = document.getElementById("myinputid");
            //这里注意的是：escape的使用
            var url = "validate?id=" + escape(target.value);
            initRequest();
            req.onreadystatechange = processRequest;
            req.open("GET", url, true);
            req.send(null);
            }
            function processRequest() {
            if (req.readyState == 4) {
            if (req.status == 200) {
            var message = req.responseXML.getElementsByTagName("number")[0].childNodes[0].nodeValue;
            setMessageUsingDOM(message);
            }
            }
            }
            function setMessageUsingDOM(message) {
            var userMessageElement = document.getElementById("myInputIdMessage");
            var messageText;
            userMessageElement.style.color = "green";
            messageText = message + " characters are typed!";
            var messageBody = document.createTextNode(messageText);
            if (userMessageElement.childNodes[0]) {
            userMessageElement.replaceChild(messageBody, userMessageElement.childNodes[0]);
            } else {
            userMessageElement.appendChild(messageBody);
            }
            }
        </script>


                    <td><b>Enter something</b></td>
                    <td>
                        <input    type="text" size="20"  id="myinputid" name="myinputfield" onkeyup="getCharacterCount()">
                    </td>
                    <td>
                        <div id="myInputIdMessage"></div>
                    </td>