ob_start();

include 'pages/login-template.php';

$loginForm = ob_get_clean();

<form action="<?php echo htmlspecialchars($_SERVER['PHP_SELF']);?>" method="post">
    <table>
        <caption>用户登录</caption>
        <tr>
           <td id="title">用户名</td>
           <td><input type="text" name="loginUserName" 
                            value="<?php isset($_POST['loginUserName']) ? htmlspecialchars($_POST['loginUserName']) : '';?>"/></td>
        </tr>
        <tr>
           <td id="title">密码</td>
           <td><input type="password" name="loginUserPassword" size="20"/></td>
        </tr>
        <tr id="btn">
           <td><input type="submit" name="Login" value="提交"/></td>
           <td><input type="reset" name="Reset" value="重置"/></td>
        </tr>
    </table>
</form>