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    1   /*
    2    * $Id: ELPageTag.java 471754 2006-11-06 14:55:09Z husted $
    3    *
    4    * Licensed to the Apache Software Foundation (ASF) under one
    5    * or more contributor license agreements.  See the NOTICE file
    6    * distributed with this work for additional information
    7    * regarding copyright ownership.  The ASF licenses this file
    8    * to you under the Apache License, Version 2.0 (the
    9    * "License"); you may not use this file except in compliance
    10   * with the License.  You may obtain a copy of the License at
    11   *
    12   *  http://www.apache.org/licenses/LICENSE-2.0
    13   *
    14   * Unless required by applicable law or agreed to in writing,
    15   * software distributed under the License is distributed on an
    16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    17   * KIND, either express or implied.  See the License for the
    18   * specific language governing permissions and limitations
    19   * under the License.
    20   */
    21  package org.apache.strutsel.taglib.bean;
    22
    23  import org.apache.struts.taglib.bean.PageTag;
    24  import org.apache.strutsel.taglib.utils.EvalHelper;
    25
    26  import javax.servlet.jsp.JspException;
    27
    28  /**
    29   * Define a scripting variable that exposes the requested page context item as
    30   * a scripting variable and a page scope bean. <p> This class is a subclass of
    31   * the class <code>org.apache.struts.taglib.bean.PageTag</code> which provides
    32   * most of the described functionality.  This subclass allows all attribute
    33   * values to be specified as expressions utilizing the JavaServer Pages
    34   * Standard Library expression language.
    35   *
    36   * @version $Rev: 471754 $
    37   */
    38  public class ELPageTag extends PageTag {
    39      /**
    40       * Instance variable mapped to "id" tag attribute. (Mapping set in
    41       * associated BeanInfo class.)
    42       */
    43      private String idExpr;
    44
    45      /**
    46       * Instance variable mapped to "property" tag attribute. (Mapping set in
    47       * associated BeanInfo class.)
    48       */
    49      private String propertyExpr;
    50
    51      /**
    52       * Getter method for "id" tag attribute. (Mapping set in associated
    53       * BeanInfo class.)
    54       */
    55      public String getIdExpr() {
    56          return (idExpr);
    57      }
    58
    59      /**
    60       * Getter method for "property" tag attribute. (Mapping set in associated
    61       * BeanInfo class.)
    62       */
    63      public String getPropertyExpr() {
    64          return (propertyExpr);
    65      }
    66
    67      /**
    68       * Setter method for "id" tag attribute. (Mapping set in associated
    69       * BeanInfo class.)
    70       */
    71      public void setIdExpr(String idExpr) {
    72          this.idExpr = idExpr;
    73      }
    74
    75      /**
    76       * Setter method for "property" tag attribute. (Mapping set in associated
    77       * BeanInfo class.)
    78       */
    79      public void setPropertyExpr(String propertyExpr) {
    80          this.propertyExpr = propertyExpr;
    81      }
    82
    83      /**
    84       * Resets attribute values for tag reuse.
    85       */
    86      public void release() {
    87          super.release();
    88          setIdExpr(null);
    89          setPropertyExpr(null);
    90      }
    91
    92      /**
    93       * Process the start tag.
    94       *
    95       * @throws JspException if a JSP exception has occurred
    96       */
    97      public int doStartTag() throws JspException {
    98          evaluateExpressions();
    99
    100         return (super.doStartTag());
    101     }
    102
    103     /**
    104      * Processes all attribute values which use the JSTL expression evaluation
    105      * engine to determine their values.
    106      *
    107      * @throws JspException if a JSP exception has occurred
    108      */
    109     private void evaluateExpressions()
    110         throws JspException {
    111         String string = null;
    112
    113         if ((string =
    114                 EvalHelper.evalString("id", getIdExpr(), this, pageContext)) != null) {
    115             setId(string);
    116         }
    117
    118         if ((string =
    119                 EvalHelper.evalString("property", getPropertyExpr(), this,
    120                     pageContext)) != null) {
    121             setProperty(string);
    122         }
    123     }
    124 }