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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  package org.apache.shiro.web.tags;
20  
21  import javax.servlet.jsp.JspException;
22  import javax.servlet.jsp.tagext.TagSupport;
23  
24  import org.slf4j.Logger;
25  import org.slf4j.LoggerFactory;
26  
27  
28  /**
29   * JSP tag that renders the tag body if the current user <em>is not</em> known to the system, either because they
30   * haven't logged in yet, or because they have no 'RememberMe' identity.
31   *
32   * <p>The logically opposite tag of this one is the {@link UserTag}.  Please read that class's JavaDoc as it explains
33   * more about the differences between Authenticated/Unauthenticated and User/Guest semantic differences.
34   *
35   * @since 0.9
36   */
37  public class GuestTag extends SecureTag {
38  
39      //TODO - complete JavaDoc
40  
41      private static final Logger log = LoggerFactory.getLogger(GuestTag.class);
42  
43      public int onDoStartTag() throws JspException {
44          if (getSubject() == null || getSubject().getPrincipal() == null) {
45              if (log.isTraceEnabled()) {
46                  log.trace("Subject does not exist or does not have a known identity (aka 'principal').  " +
47                          "Tag body will be evaluated.");
48              }
49              return TagSupport.EVAL_BODY_INCLUDE;
50          } else {
51              if (log.isTraceEnabled()) {
52                  log.trace("Subject exists or has a known identity (aka 'principal').  " +
53                          "Tag body will not be evaluated.");
54              }
55              return TagSupport.SKIP_BODY;
56          }
57      }
58  
59  }