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14.2.3 隐式的权限
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14.2.3 隐式的权限
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2006-10-13 14:41:00
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<div style='float:left;width:49%'>·<a href='100165423.htm'>14.2 对Framework中安全性的支持</a></div><div style='float:right;width:49%'>·<a href='100165424.htm'>14.2.1 要求权限</a></div><div style='float:left;width:49%'>·<a href='100165425.htm'>14.2.2 请求权限</a></div><div style='float:right;width:49%'>·<a href='100165427.htm'>14.2.4 拒绝权限</a></div><div style='float:left;width:49%'>·<a href='100165428.htm'>14.2.5 断言权限</a></div><div style='float:right;width:49%'>·<a href='100165429.htm'>14.2.6 创建代码访问权限</a></div></div>
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<div id="text"> <link href="css.css" rel="stylesheet" type="text/css" /><h3 style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 0cm; MARGIN-RIGHT: 0cm; FTEL: 8.15pt"><a ftel="_Toc507815606"><span lang="EN-US">14.2.3 </span></a><span style="FONT-FAMILY: 黑体">隐式的权限</span></h3>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">在赋予权限时，通常有一些隐式的语句可以赋予其他权限。例如，如果赋予了访问</span><span lang="EN-US">C:\</span><span style="FONT-FAMILY: 宋体">的权限</span><span lang="EN-US">FileIOPermission</span><span style="FONT-FAMILY: 宋体">，就隐含着也可以访问</span><span lang="EN-US">C:\</span><span style="FONT-FAMILY: 宋体">的子目录</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">这是</span><span lang="EN-US">Windows</span><span style="FONT-FAMILY: 宋体">账户安全性允许的</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">。</span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体">如果要检查赋予权限时是否隐式地赋予了其他的权限作为子集，可以使用下面的代码：</span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">// Example from SecurityApp3</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> class SecurityApp3</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> static void Main(string[] args)</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> CodeAccessPermission permissionA = </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> new FileIOPermission(FileIOPermissionAccess.AllAccess, @"C:\");</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> CodeAccessPermission permissionB = </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> new FileIOPermission(FileIOPermissionAccess.Read, @"C:\temp");</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> if (permissionB.IsSubsetOf(permissionA))</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> Console.WriteLine("PermissionB is a subset of PermissionA");</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> else</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> Console.WriteLine("PermissionB is NOT a subset of PermissionA");</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">代码的执行结果如下：</span></p>
<p class="a6" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">PermissionB is a subset of PermissionA</span></p></div>
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<h1 id="divCurrentNode2" style="color: #b83507; width: 100%; text-align: left; font-size: 12px; padding-left: 2px">当前章节:<a href='100165426.htm'><font color='red'>14.2.3 隐式的权限</font></a></h1>
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<div style='float:left;width:49%'>·<a href='100165423.htm'>14.2 对Framework中安全性的支持</a></div><div style='float:right;width:49%'>·<a href='100165424.htm'>14.2.1 要求权限</a></div><div style='float:left;width:49%'>·<a href='100165425.htm'>14.2.2 请求权限</a></div><div style='float:right;width:49%'>·<a href='100165427.htm'>14.2.4 拒绝权限</a></div><div style='float:left;width:49%'>·<a href='100165428.htm'>14.2.5 断言权限</a></div><div style='float:right;width:49%'>·<a href='100165429.htm'>14.2.6 创建代码访问权限</a></div></div>
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