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java安全－论证授权

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<a name="navskip"></a><td height="25" colspan="4"><img alt="4.JAAS 中的授权" src="imagemaster/titlebar4.jpg" border="0" height="25" width="562"></td>
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<td width="90%"><font size="4" face="Verdana, Arial, Helvetica"><b>JAAS 主程序示例</b></font></td><td width="200" align="right"><font size="1" face="Verdana, Arial, Helvetica"><nobr>   第 7 页（共9 页）</nobr></font></td>
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<p>下面是这个示例的主应用程序（从命令行调用）。
它实例化登录环境、然后登录、尝试执行两个敏感对象（一个对象使用程序性授权，另一个对象使用声明性授权），最后注销。
接下来，我们将更深入地研究主程序的两个元素：程序性授权和声明性授权。</p>
<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
import java.security.*;
import javax.security.auth.*;
import javax.security.auth.callback.*;
import javax.security.auth.login.*;
//
// This is the main program in the JAAS Example.  It creates a Login  
// Context, logs the user in based on the settings in the Login  
// Configuration file,and calls two sensitive pieces of code, the  
// first using programmatic authorization, and the second using 
// declarative authorization.
public class JAASExample {

     static LoginContext lc = null;

     public static void main( String[] args) {
       //
       // Create a login context
       try {
         lc = new LoginContext("JAASExample",
            new UsernamePasswordCallbackHandler());
       } catch (LoginException le) {
         System.out.println( "Login Context Creation Error" );
         System.exit(1);
       }
       //

       // Login
       try {
         lc.login();
       } catch (LoginException le) {
         System.out.println( "\nOVERALL AUTHENTICATION FAILED\n" );
         System.exit(1);
       }
       System.out.println( "\nOVERALL AUTHENTICATION SUCCEEDED\n" );
       System.out.println( lc.getSubject() );
       //
       // Call the sensitive PayrollAction code, which uses programmatic
       // authorization.
       try {
         <code>Subject</code>.doAs( lc.getSubject(), new PayrollAction() );
       } catch (AccessControlException e) {
         System.out.println( "Payroll Access DENIED" );
       }
       //
       // Call the sensitive PersonnelAction code, which uses declarative
       // authorization.
       try {
         <code>Subject</code>.doAsPrivileged( lc.getSubject(), new PersonnelAction(), null );
       } catch (AccessControlException e) {
         System.out.println( "Personnel Access DENIED" );
       }
       try {
         lc.logout();
       } catch (LoginException le) {
         System.out.println( "Logout FAILED" );
         System.exit(1);
       }
       System.exit(0);

     }
}
</code>
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