html5 video无法快进怎么办

var vol = 0.1;  //1代表100%音量，每次增减0.1
var time = 2; //单位秒，每次增减10秒
 
 
function listenKeyboard() {
    var videoElement = document.getElementById("video");
    document.onkeyup = function (event) {//键盘事件
 
        var e = event || window.event || arguments.callee.caller.arguments[0];
 
        //鼠标上下键控制视频音量
        if (e && e.keyCode === 38) {
            console.log("音量加1");
            // 按 向上键
            videoElement.volume !== 1 ? videoElement.volume += vol : 1;
            return false;
 
        } else if (e && e.keyCode === 40) {
            console.log("音量减1");
            // 按 向下键
            videoElement.volume !== 0 ? videoElement.volume -= vol : 1;
            return false;
 
        } else if (e && e.keyCode === 37) {
            console.log("倒退1秒");
            // 按 向左键
            videoElement.currentTime !== 0 ? videoElement.currentTime = videoElement.currentTime -= time : 1;
            return false;
 
        } else if (e && e.keyCode === 39) {
            console.log("前进2秒,当前时间是:"+videoElement.currentTime+",视频长度是："+videoElement.duration);
            // 按 向右键
            var currPlayTime = videoElement.currentTime ;
            if (currPlayTime !== videoElement.duration){
                var afterSetTime = currPlayTime + time ;
                console.log('afterSetTime should be :'+afterSetTime) ;
                videoElement.currentTime = afterSetTime ;
                console.log('afterSetTime is :'+videoElement.currentTime) ;
            }else {
                videoElement.currentTime = videoElement.currentTime + 1;
            }
            console.log("快进后的时间是:"+videoElement.currentTime);
            return false;
        } else if (e && e.keyCode === 32) {
            console.log("暂停");
            // 按空格键 判断当前是否暂停
            videoElement.paused === true ? videoElement.play() : videoElement.pause();
            return false;
 
        }
 
    }
}

        String rangeString = request.getHeader("Range");//如果是video标签发起的请求就不会为null
            if (StringUtils.isNotBlank(rangeString)){
                long range = Long.valueOf(rangeString.substring(rangeString.indexOf("=") + 1, rangeString.indexOf("-")));
                response.setHeader("Access-Control-Allow-Origin", "*");
                response.setHeader("Content-Type", "video/mp4");
                response.setHeader("content-disposition", "attachment;filename=" + URLEncoder.encode(file.getName() , "UTF-8"));
                int fileLength = (int)file.length() ;
                response.setContentLength(fileLength);//10000是视频文件的大小，上传文件时都会有这些参数的
                response.setHeader("Content-Range", String.valueOf(range + (fileLength-1)));//拖动进度条时的断点，其中10000是上面的视频文件大小，改成你的就好
                response.setHeader("Accept-Ranges", "bytes");
//            response.setHeader("Etag", "W/"9767057-1323779115364"");//上传文件时都会有这些参数的
                response.setHeader("Etag", "737060cd8c284d8af7ad3082f209582d");//上传文件时都会有这些参数的
            }