Question

我需要通过Ajax调用在浏览器中使用servlet程序显示hello world但是点击按钮我不会显示它可能是这个错误的原因：

Uncaught NetworkError：无法在'XMLHttpRequest'上执行'send'：无法加载'file：/// D：/ workspace / Poc_Ajax / WebContent / WEB-INF / HelloWorld'。

<!DOCTYPE html>
<html>
<head>
<script>
function getXMLHttpRequest() {
    var xmlHttpReq = false;
    // to create XMLHttpRequest object in non-Microsoft browsers
    if (window.XMLHttpRequest) {
        xmlHttpReq = new XMLHttpRequest();
    } else if (window.ActiveXObject) {
        try {
            // to create XMLHttpRequest object in later versions
            // of Internet Explorer
            xmlHttpReq = new ActiveXObject("Msxml2.XMLHTTP");
        } catch (exp1) {
            try {
                // to create XMLHttpRequest object in older versions
                // of Internet Explorer
                xmlHttpReq = new ActiveXObject("Microsoft.XMLHTTP");
            } catch (exp2) {
                xmlHttpReq = false;
            }
        }
    }
    return xmlHttpReq;
}
/*
 * AJAX call starts with this function
 */
function makeRequest() {
    var xmlHttpRequest = getXMLHttpRequest();
    xmlHttpRequest.onreadystatechange = getReadyStateHandler(xmlHttpRequest);
    xmlHttpRequest.open("POST", "HelloWorld", true);
    xmlHttpRequest.setRequestHeader("Content-Type",
            "application/x-www-form-urlencoded");
    xmlHttpRequest.send();
}

/*
 * Returns a function that waits for the state change in XMLHttpRequest
 */
function getReadyStateHandler(xmlHttpRequest) {

    // an anonymous function returned
    // it listens to the XMLHttpRequest instance
    return function() {
        if (xmlHttpRequest.readyState == 4) {
            if (xmlHttpRequest.status == 200) {
                document.getElementById("hello").innerHTML = xmlHttpRequest.responseText;
            } else {
                alert("HTTP error " + xmlHttpRequest.status + ": " + xmlHttpRequest.statusText);
            }
        }
    };
}
</script>
</head>
<body>
<div>Getting Started with AJAX using JAVA: Hello World!</div>
<div id="hello"><button type="button" onclick="makeRequest()">Say Hello!</button></div>
</body>
</html>

Answer 1

要运行servlet程序，您需要向配置为执行servlet的Web服务器发出HTTP请求。

您的Ajax URL（显示在错误消息中）以file://开头，因此您尝试处理本地文件而不是网络服务器。

安装网络服务器（例如Tomcat）。从中加载HTML文档。确保"HelloWorld"是从该HTML文档到servlet URL的相对URI。

Uncaught NetworkError：无法在'XMLHttpRequest'上执行'send'

1 个答案: