本文介绍使用JavaScript通过位运算实现简单的权限管理系统。通过定义Read、Write、Delete三种权限对应的位值，利用按位与和按位或操作进行权限的获取与设置。代码展示了如何封装权限对象，并提供Java风格的调用示例，适用于需要轻量级权限控制的场景。
作者: slightboy, 时间: 2006-10-17
本文为 JavaScript 实现版本，此前文章已阐述相关原理，此处不再赘述。
如需了解具体原理，请参阅 VBS 版本。
权限类型定义与核心逻辑
var PermissionType =
{
Read : 1,
Write : 2,
Delete : 4
}
function PermissionSetComponent(value)
{
this.Value = value;
this.getRead = function()
{
return this.getValue(PermissionType.Read);
}
this.setRead = function(value)
{
this.setValue(PermissionType.Read, value);
}
this.Read = function()
{
if (arguments.length > 0)
this.setValue(PermissionType.Read, arguments[0]);
else
return this.getValue(PermissionType.Read);
}
this.Write = function()
{
if (arguments.length > 0)
this.setValue(PermissionType.Write, arguments[0]);
else
return this.getValue(PermissionType.Write);
}
this.Delete = function()
{
if (arguments.length > 0)
this.setValue(PermissionType.Delete, arguments[0]);
else
return this.getValue(PermissionType.Delete);
}
this.getValue = function(permissionType)
{
return (this.Value & permissionType) == permissionType;
}
this.setValue = function(permissionType, value)
{
if (value)
this.Value |= permissionType;
else
this.Value &= ~permissionType;
}
}
权限测试与输出示例
var PermissionSet = new PermissionSetComponent(0);
w("Read:");
PermissionSet.Read(false);
w(PermissionSet.Value +" "+ PermissionSet.Read());
PermissionSet.Read(true);
w(PermissionSet.Value +" "+ PermissionSet.Read());
w("Write:");
PermissionSet.Write(false);
w(PermissionSet.Value +" "+ PermissionSet.Write());
PermissionSet.Write(true);
w(PermissionSet.Value +" "+ PermissionSet.Write());
w("Delete:");
PermissionSet.Delete(false);
w(PermissionSet.Value +" "+ PermissionSet.Delete());
PermissionSet.Delete(true);
w(PermissionSet.Value +" "+ PermissionSet.Delete());
function w(o)
{
Response.Write(o +"<br />");
}
注: 红色部分为 java 风格写法 不是本例所必须.
只是做一个展示, 如果你比较喜欢 java 风格也可以选择这种写法.