位和位掩码是我一直以来都很难理解的东西，但我想学习如何在PHP中使用它们进行设置等操作。
最终我找到了一个声称可以完美实现这个功能的类，据我所知，它似乎能够正常工作，但我不确定这是否是最佳做法。我会在下面附上带有示例代码的类文件，以便展示其工作方式。
如果你有相关经验，请告诉我如何改进它，无论是为了性能还是其他方面。我真的很想学习这个知识点，虽然我一直在阅读相关文献，但到目前为止，它对我来说仍然很难理解。
以下是该类...
<?php
class bitmask
{
/**
* This array is used to represent the users permission in usable format.
*
* You can change remove or add valuesto suit your needs.
* Just ensure that each element defaults to false. Once you have started storing
* users permsisions a change to the order of this array will cause the
* permissions to be incorectly interpreted.
*
* @type Associtive array
*/
public $permissions = array(
"read" => false,
"write" => false,
"delete" => false,
"change_permissions" => false,
"admin" => false
);
/**
* This function will use an integer bitmask (as created by toBitmask())
* to populate the class vaiable
* $this->permissions with the users permissions as boolean values.
* @param int $bitmask an integer representation of the users permisions.
* This integer is created by toBitmask();
*
* @return an associatve array with the users permissions.
*/
public function getPermissions($bitMask = 0)
{
$i = 0;
foreach ($this->permissions as $key => $value)
{
$this->permissions[$key] = (($bitMask & pow(2, $i)) != 0) ? true : false;
// Uncomment the next line if you would like to see what is happening.
//echo $key . " i= ".strval($i)." power=" . strval(pow(2,$i)). "bitwise & = " . strval($bitMask & pow(2,$i))."<br>";
$i++;
}
return $this->permissions;
}
/**
* This function will create and return and integer bitmask based on the permission values set in
* the class variable $permissions. To use you would want to set the fields in $permissions to true for the permissions you want to grant.
* Then call toBitmask() and store the integer value. Later you can pass that integer into getPermissions() to convert it back to an assoicative
* array.
*
* @return int an integer bitmask represeting the users permission set.
*/
function toBitmask()
{
$bitmask = 0;
$i = 0;
foreach ($this->permissions as $key => $value)
{
if ($value)
{
$bitmask += pow(2, $i);
}
$i++;
}
return $bitmask;
}
}
?>
我如何将权限设置/保存为位掩码值？
<?php
/**
* Example usage
* initiate new bitmask object
*/
$perms = new bitmask();
/**
* How to set permissions for a user
*/
$perms->permissions["read"] = true;
$perms->permissions["write"] = true;
$perms->permissions["delete"] = true;
$perms->permissions["change_permissions"] = true;
$perms->permissions["admin"] = false;
// Converts to bitmask value to store in database or wherever
$bitmask = $perms->toBitmask(); //in this example it is 15
$sql = "insert into user_permissions (userid,permission) values(1,$bitmask)";
echo $sql; //you would then execute code to insert your sql.
?>
根据位掩码值获取数组项并返回true/false的示例代码...
<?php
/**
* Example usage to get the bitmask value from database or session/cache.... then put it to use.
* $permarr returns an array with true/false for each array value based on the bit value
*/
$permarr = $perms->getPermissions($bitmask);
if ($permarr["read"])
{
echo 'user can read: <font color="green">TRUE</font>';
}
else {
echo 'user can read: <font color="red">FALSE</font>';
}
//user can WRITE permission
if ($permarr["write"])
{
echo '<br>user can write: <font color="green">TRUE</font>';
}
else {
echo '<br>user can write: <font color="red">FALSE</font>';
}
?>
select userid from user_permissions where (permission & 1) = 1。 - grandouassoucan_read的列吗？我个人更喜欢使用后者，但也很想知道其他人的想法... - alexcan_read更明确，但如果您有更多的设置，也许您不想要 15 列can_boo、can_zoo。 - grandouassou