原来有东西是用seam开发的，现在需要与另一个单点登陆系统做接口
啥都做好了，就搞不清seam的登陆机制  如何让他自动登陆 有做过的给点提示

请看<<Seam Reference>>中的 Security 部分

在做portletbridge版本的seam应用的时候接触到过。
而portletbridge也有实现seam和jboss portal使用的SSO。
可以下载一个portletbridge版本的seam extention看看。

svn co http://anonsvn.jboss.org/repos/portletbridge/ portletbridge

package org.jboss.portletbridge.extension.seam;

import org.jboss.seam.ScopeType;
import org.jboss.seam.Component;
import org.jboss.seam.core.Events;
import org.jboss.seam.contexts.Contexts;
import org.jboss.seam.annotations.*;
import org.jboss.seam.annotations.intercept.BypassInterceptors;
import org.jboss.seam.log.Log;
import org.jboss.seam.log.Logging;
import org.jboss.seam.security.Identity;
import org.jboss.seam.security.Credentials;
import org.jboss.portletbridge.BufferedRenderResponseWrapper;
import org.jboss.portletbridge.context.ServletApplicationScopeSessionMap;
import org.jboss.portletbridge.context.PortletApplicationScopeSessionMap;
import org.jboss.portal.portlet.impl.jsr168.api.RenderRequestImpl;

import javax.faces.context.ExternalContext;
import javax.faces.context.FacesContext;
import javax.security.auth.login.LoginException;
import javax.portlet.RenderRequest;
import javax.portlet.RenderResponse;
import javax.portlet.PortletRequest;
import javax.portlet.faces.Bridge;
import javax.servlet.http.HttpServletRequest;
import java.lang.reflect.Method;
import java.security.Principal;
import java.io.Serializable;

@Name("org.jboss.seam.security.identity")
@Scope(ScopeType.SESSION)
@BypassInterceptors
@Install(precedence = Install.APPLICATION, classDependencies = "javax.portlet.Portlet")
@Startup
public class PortalIdentity extends Identity
{

   private static final Log log = Logging.getLog(PortalIdentity.class);

   private JBossLoginDelegate loginDelegate = new JBossLoginDelegate();

   @In
   private Credentials credentials;

   private Principal bridgePrincipal;

   public Credentials getCredentials()
   {
      if (credentials == null)
      {
         credentials = (Credentials)Component.getInstance(Credentials.class);
      }
      return credentials;
   }

   public PortalIdentity()
   {
      super();
   }

   private boolean isPortletPhase()
   {
      return (FacesContext.getCurrentInstance().getExternalContext().getRequestMap().get(Bridge.PORTLET_LIFECYCLE_PHASE)
         instanceof Bridge.PortletPhase);
   }

   /**
    * Attempts to authenticate the user.  This method is distinct to the authenticate() method in that it raises events
    * in response to whether authentication is successful or not.  The following events may be raised by calling
    * login():
    * <p/>
    * org.jboss.seam.security.loginSuccessful - raised when authentication is successful
    * org.jboss.seam.security.loginFailed - raised when authentication fails org.jboss.seam.security.alreadyLoggedIn -
    * raised if the user is already authenticated
    *
    * @return String returns "loggedIn" if user is authenticated, or null if not.
    */
   @Override
   public String login()
   {
      try
      {
         if (isLoggedIn())
         {
            // If authentication has already occurred during this request via a silent login,
            // and login() is explicitly called then we still want to raise the LOGIN_SUCCESSFUL event,
            // and then return.

            if (!isPortletPhase())
            {
               if (Contexts.isEventContextActive() && Contexts.getEventContext().isSet("org.jboss.seam.security.silentLogin"))
               {
                  if (Events.exists())
                  {
                     Events.instance().raiseEvent(EVENT_LOGIN_SUCCESSFUL);
                  }
                  return "loggedIn";
               }

               if (Events.exists())
               {
                  Events.instance().raiseEvent(EVENT_ALREADY_LOGGED_IN);
               }
               return "loggedIn";

            }
         }

         authenticate();

         if (!isLoggedIn())
         {
            throw new LoginException();
         }

         if (log.isDebugEnabled())
         {
            log.debug("Login successful for: " + getCredentials().getUsername());
         }

         if (Events.exists())
         {
            Events.instance().raiseEvent(EVENT_LOGIN_SUCCESSFUL);
         }
         return "loggedIn";
      }
      catch (LoginException ex)
      {
         getCredentials().invalidate();

         if (log.isDebugEnabled())
         {
            log.debug("Login failed for: " + getCredentials().getUsername(), ex);
         }
         if (Events.exists())
         {
            Events.instance().raiseEvent(EVENT_LOGIN_FAILED, ex);
         }
      }

      return null;
   }

   /*
   * (non-Javadoc)
   *
   * @see org.jboss.seam.security.Identity#authenticate()
   */
   @Override
   public void authenticate() throws LoginException
   {

      if (!isLoggedIn())
      {
         loginDelegate.login(getUsername(), getPassword());
      }
   }

   @Override
   public void logout()
   {
      loginDelegate.logout();
      super.logout();
   }

   /*
   * (non-Javadoc)
   *
   * @see org.jboss.seam.security.Identity#hasPermission(java.lang.String,
   * java.lang.String, java.lang.Object[])
   */
   @Override
   public boolean hasPermission(String name, String action, Object... arg)
   {
      return super.hasPermission(name, action, arg);
   }

   /*
   * (non-Javadoc)
   *
   * @see org.jboss.seam.security.Identity#hasRole(java.lang.String)
   */
   @Override
   public boolean hasRole(String role)
   {
      return getRenderRequest() != null && getRenderRequest().getRealRequest().isUserInRole(role);
   }

   private RenderRequestImpl getRenderRequest()
   {
      if (FacesContext.getCurrentInstance() != null)
      {
         Object responseObject = FacesContext.getCurrentInstance().getExternalContext().getRequest();
         if (responseObject instanceof RenderRequest)
         {
            return (RenderRequestImpl)responseObject;
         }
         else
         {
            return null;
         }
      }
      else
      {
         return null;
      }
   }

   /*
   * (non-Javadoc)
   *
   * @see org.jboss.seam.security.Identity#isLoggedIn()
   */

   @Override
   public boolean isLoggedIn()
   {
      return getPrincipal() != null;
   }

   /*
   * (non-Javadoc)
   *
   * @see org.jboss.seam.security.Identity#isLoggedIn(boolean)
   */
   @Override
   public boolean isLoggedIn(boolean attemptLogin)
   {
      return isLoggedIn();
   }

   @Override
   public String getUsername()
   {
      if (!isLoggedIn())
      {
         return super.getUsername();
      }
      else
      {
         String userName = null;
         if (getRenderRequest() != null && getRenderRequest().getRealRequest().getUserPrincipal() != null)
         {
            userName = getRenderRequest().getRealRequest().getRemoteUser();
         }
         return userName;
      }
   }

   //private int counter = 0;


   public Principal getPrincipal()
   {
      if (FacesContext.getCurrentInstance() != null)
      {


         if (isPortletPhase())
         {
            if (getRenderRequest() != null)
            {
               bridgePrincipal = getRenderRequest().getRealRequest().getUserPrincipal();
            }
         }
         if (bridgePrincipal == null){
            bridgePrincipal = FacesContext.getCurrentInstance().getExternalContext().getUserPrincipal();
         }
      }
      return bridgePrincipal;
   }

   /**
    * jboss login delegate
    *
    * @author Egor Kolesnikov
    */
   private static class JBossLoginDelegate
   {
      private Class authenticationClass;
      private Object jbossAuthentication;

      public JBossLoginDelegate()
      {
         try
         {
            authenticationClass = Class
               .forName("org.jboss.web.tomcat.security.login.WebAuthentication");
         }
         catch (ClassNotFoundException ex)
         {
            log.info("JBoss Web Authentication is not available...");
         }
         try
         {
            jbossAuthentication = authenticationClass.newInstance();
         }
         catch (Exception e)
         {
            log.error("JBoss Web Authentication instantiation "
               + "exception, Web Authentication disabled", e);
         }
      }

      public void login(String username, String password)
      {
         if (authenticationClass == null || jbossAuthentication == null)
         {
            return;
         }
         try
         {
            Method m = authenticationClass.getMethod("login", String.class, Object.class);
            m.invoke(jbossAuthentication, username, password);
         }
         catch (Exception ex)
         {
            log.error("Error logging out with JBoss Web Authentication", ex);
         }
      }

      public void logout()
      {
         if (authenticationClass == null || jbossAuthentication == null)
         {
            return;
         }
         try
         {
            Method m = authenticationClass.getMethod("logout");
            m.invoke(jbossAuthentication);
         }
         catch (Exception ex)
         {
            log.error("Error logging out with JBoss Web Authentication", ex);
         }
      }
   }

}