InvalidateTag


1   /*
2    * Copyright 1999,2004 The Apache Software Foundation.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */ 
16  
17  package org.apache.taglibs.cache;
18  
19  import javax.servlet.jsp.*;
20  import javax.servlet.jsp.tagext.*;
21  import org.apache.taglibs.standard.lang.support.ExpressionEvaluatorManager;
22  
23  /**
24   * <p>Invalidates a particular cache entry, or an entire cache.</p>
25   *
26   * @author Shawn Bayern
27   */
28  
29  public class InvalidateTag extends TagSupport {
30  
31      //*********************************************************************
32      // Private state
33  
34      String   nameExpr;                    // tag attribute
35      String   keyExpr;                 // tag attribute
36  
37      int scope;                      // parsed tag attribute
38      String   name, key;                   // parsed tag attribute
39  
40      //*********************************************************************
41      // Tag logic
42  
43      public int doStartTag() throws JspException {
44        evaluateExpressions();
45        if (keyExpr == null || key == null) {
46          // invalidate whole cache
47          CacheUtil.invalidateCache(scope, name, pageContext);
48        } else {
49          // invalidate cache item
50          CacheUtil.invalidateCachedItem(scope, name, key, pageContext);
51        }
52        return SKIP_BODY;
53      }
54  
55      //*********************************************************************
56      // Attribute accessors
57  
58      public void setScope(String   scope) {
59        if (scope.equalsIgnoreCase("page"))
60      this.scope = PageContext.PAGE_SCOPE;
61        else if (scope.equalsIgnoreCase("request"))
62          this.scope = PageContext.REQUEST_SCOPE;
63        else if (scope.equalsIgnoreCase("session"))
64          this.scope = PageContext.SESSION_SCOPE;
65        else if (scope.equalsIgnoreCase("application"))
66          this.scope = PageContext.APPLICATION_SCOPE;
67        else
68          throw new IllegalArgumentException  ("invalid scope");
69      }
70  
71      public void setName(String   nameExpr) {
72        this.nameExpr = nameExpr;
73      }
74  
75      public void setKey(String   keyExpr) {
76        this.keyExpr = keyExpr;
77      }
78  
79  
80      //*********************************************************************
81      // Constructor and initialization
82  
83      public InvalidateTag() {
84        super();
85        init();
86      }
87  
88      private void init() {
89        scope = PageContext.APPLICATION_SCOPE;
90        name = nameExpr = null;
91        key = keyExpr = null;
92      }
93      
94  
95      //*********************************************************************
96      // Private utility methods
97  
98      private void evaluateExpressions() throws JspException {
99        if (nameExpr != null)
100         name = (String  ) ExpressionEvaluatorManager.evaluate(
101           "name",
102           nameExpr,
103           String  .class,
104           this,
105           pageContext);
106       if (keyExpr != null)
107         key = (String  ) ExpressionEvaluatorManager.evaluate(
108           "key",
109           keyExpr,
110           String  .class,
111           this,
112           pageContext);
113     }
114 
115 }
116
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