function usersearch() {
    var key = $("userKey").value;
    if (key == "") {
        alert("请输入搜索关键字。");
        $("Key").focus();
        return false;
    }
    key = unescape(key);   
    var url;
    switch($("userType").value) {
        case "1":
            url = "PLesson.html?Key=" + key;
            break;
        case "2":
            url = "ILesson.html?Key=" + key;
            break;                
        default:
            url = "Lecturer.html?Key=" + key;
            break;
    }
    location.href = url;
    return false;
}
function vImg(id) {
    $(id).innerHTML = "<img src='/CodeImage.html?id=" + Math.random() + "'alt='点击刷新' title='点击刷新' height='20' align='absmiddle' style='cursor:pointer;' onclick='return vImg(\"" + id + "\")' />";
    return false;
}