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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="3.JAAS 中的认证" src="imagemaster/titlebar3.jpg" border="0" height="25" width="562"></td>
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<td width="90%"><font size="4" face="Verdana, Arial, Helvetica"><b>AlwaysLoginModule</b></font></td><td width="200" align="right"><font size="1" face="Verdana, Arial, Helvetica"><nobr>   第 12 页（共13 页）</nobr></font></td>
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<p> 
<code>AlwaysLoginModule</code> 认证将始终成功，
所以实际上它仅用于通过 <code>NameCallback</code> 函数获取用户名。
假设其它登录模块都成功，<code>AlwaysLoginModule</code> 的 <code>commit()</code>
方法将创建一个带用户名的新 <code>PrincipalImpl</code> 对象并将它添加到 <code>Subject</code> 的 <code>Principal</code> 集中。注销将除去 <code>Subject</code> 的 <code>Principal</code> 集
中的 <code>PrincipalImpl</code>。</p>
<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
import java.security.*;
import javax.security.auth.*;
import javax.security.auth.spi.*;
import javax.security.auth.callback.*;
import javax.security.auth.login.*;
import java.io.*;
import java.util.*;

// This is a JAAS Login Module that always succeeds.  While not realistic, 
// it is designed to illustrate the bare bones structure of a Login Module 
// and is used in examples that show the login configuration file 
// operation.

public class AlwaysLoginModule implements LoginModule {

     private <code>Subject</code> subject;
     private <code>Principal</code> principal;
     private CallbackHandler callbackHandler;
     private String username;
     private boolean loginSuccess;
     //
     // Initialize sets up the login module.  sharedState and options are
     // advanced features not used here
     public void initialize(<code>Subject</code> sub, CallbackHandler cbh,
       Map sharedState, Map options) {

       subject = sub;
       callbackHandler = cbh;
       loginSuccess = false;
     }
     //
     // The login phase gets the userid from the user
     public boolean login() throws LoginException {
       //
       // Since we need input from a user, we need a callback handler
       if (callbackHandler == null) {
         throw new LoginException( "No CallbackHandler defined");

       }
       Callback[] callbacks = new Callback[1];
       callbacks[0] = new NameCallback("Username");
       //
       // Call the callback handler to get the username
       try {
         System.out.println( "\nAlwaysLoginModule Login" );
         callbackHandler.handle(callbacks);
         username = ((NameCallback)callbacks[0]).getName();
       } catch (IOException ioe) {
         throw new LoginException(ioe.toString());
       } catch (UnsupportedCallbackException uce) {
         throw new LoginException(uce.toString());
       }
       loginSuccess = true;
       System.out.println();
       System.out.println( "Login: AlwaysLoginModule SUCCESS" );
       return true;
     }
     //
     // The commit phase adds the principal if both the overall authentication
     // succeeds (which is why commit was called) as well as this particular
     // login module
     public boolean commit() throws LoginException {
       //
       // Check to see if this login module succeeded (which it always will

       // in this example)
       if (loginSuccess == false) {
         System.out.println( "Commit: AlwaysLoginModule FAIL" );
         return false;
       }
       //
       // If this login module succeeded too, then add the new principal
       // to the subject (if it does not already exist)
       principal = new PrincipalImpl(username);
       if (!(subject.getPrincipals().contains(principal))) {
         subject.getPrincipals().add(principal);
       }
       System.out.println( "Commit: AlwaysLoginModule SUCCESS" );
       return true;
     }
     //
     // The abort phase is called if the overall authentication fails, so
     // we have to clean up the internal state
     public boolean abort() throws LoginException {

       if (loginSuccess == false) {
         System.out.println( "Abort: AlwaysLoginModule FAIL" );
         principal = null;
         return false;
       }
       System.out.println( "Abort: AlwaysLoginModule SUCCESS" );
       logout();

       return true;
     }
     //
     // The logout phase cleans up the state
     public boolean logout() throws LoginException {

       subject.getPrincipals().remove(principal);
       loginSuccess = false;
       principal = null;
       System.out.println( "Logout: AlwaysLoginModule SUCCESS" );
       return true;
      }
}
</code>
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