如何回显类功能？

Is this possible to echo the class function? I tried this but I'm getting error;

<input type="text" name="query">
ex. empid('1');

    <?php
    include 'class/class.sample.php';
    $sampleObj = new sample();
    $function = $_POST['query']; //ex empid('1');
    echo $drObj->$function;
    ?>

I don't believe you can pass that just as is, but that doesn't mean it can't be achieved. You could write a small function that will parse the input into values you can use to call the desired function. Something like this

<?php
// I've commented your include because it doesn't benefit this example
//include 'class/class.sample.php';
$sampleObj = new sample();
//$function = $_POST['query']; //ex empid('1');

// set input hardcoded for the benefit of this example
$output = fetchFunction("empid('1','2','3')");
call_user_func_array(array($sampleObj, $output['function']), $output['parameters']);

/**
 * Use this function to parse input like "empid('1','2')"
 * to array('function'=>'empid',parameters=>array(1,2))
 * This can be used in a call_user_func_array
 *
 * @param $input
 * @return array
 */
function fetchFunction($input){
    // match inside () to get the parameters
    preg_match('/(?<=\()(.+)(?=\))/is', $input, $parameters);

    return array(
        'parameters' => explode(',', str_replace(array('\'','"'),'',$parameters[0])),
        'function' => substr($input,0,strpos($input,'('))
    );
}


class sample{
    public function empid($id){
        print_r(func_get_args());
    }
}

I've added a dummy class to show the output, and didn't include any check for existing functions for instance (possible with something like method_exists). You'll need to change that to work with your own class setup and functions.