struts-logic.html

struts api,学习使用struts必备的文档

<tr class="oddRow">
<td align="center">offset</td>
<td>
      <p>The zero-relative index of the starting point at which entries from
      the underlying collection will be iterated through.  This can be either
      an integer that directly expresses the desired value, or the name of a
      JSP bean (in any scope) of type <code>java.lang.Integer</code> that
      defines the desired value.  If not present, zero is assumed (meaning
      that the collection will be iterated from the beginning.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="evenRow">
<td align="center">property</td>
<td>
      <p>Name of the property, of the JSP bean specified by <code>name</code>,
      whose getter returns the collection to be iterated.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="oddRow">
<td align="center">scope</td>
<td>
      <p>The bean scope within which to search for the bean named by the
      <code>name</code> property, or "any scope" if not specified.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="evenRow">
<td align="center">type</td>
<td>
      <p>Fully qualified Java class name of the element to be exposed through
      the JSP bean named from the <code>id</code> attribute.  If not present,
      no type conversions will be performed.  NOTE:  The actual elements of
      the collection must be assignment-compatible with this class, or a
      request time ClassCastException will occur.</p>
      
            [RT Expr]
          </td>
</tr>
</table>
</div>
<p>
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</p>
<h3 id="lessEqual">
<strong>lessEqual</strong> - 
    Evaluate the nested body content of this tag if the requested
    variable is less than or equal to the specified value.
    </h3>
<div class="indent">
    <p>Compares the variable specified by one of the selector attributes
    against the specified constant value.  The nested body content of this
    tag is evaluated if the variable is <strong>less than or equal</strong>
    to the value.</p>
    <table class="tag-attributes">
<thead>
<tr>
<th class="attribute">Attribute Name</th>
<th>Description</th>
</tr>
</thead>
<tr class="evenRow">
<td align="center">cookie</td>
<td>
      <p>The variable to be compared is the value of the cookie whose
      name is specified by this attribute.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="oddRow">
<td align="center">header</td>
<td>
      <p>The variable to be compared is the value of the header whose
      name is specified by this attribute.  The name match is performed
      in a case insensitive manner.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="evenRow">
<td align="center">name</td>
<td>
      <p>The variable to be compared is the JSP bean specified by this
      attribute, if <code>property</code> is not specified, or the value
      of the specified property of this bean, if <code>property</code>
      is specified.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="oddRow">
<td align="center">parameter</td>
<td>
      <p>The variable to be compared is the first, or only, value of the
      request parameter specified by this attribute.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="evenRow">
<td align="center">property</td>
<td>
      <p>The variable to be compared is the property (of the bean specified
      by the <code>name</code> attribute) specified by this attribute.
      The property reference can be simple, nested, or indexed.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="oddRow">
<td align="center">scope</td>
<td>
      <p>The bean scope within which to search for the bean named by the
      <code>name</code> property, or "any scope" if not specified.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="evenRow">
<td align="center">value</td>
<td>
      <p>The constant value to which the variable, specified by other
      attribute(s) of this tag, will be compared.</p>
      
            [Required]
          
            [RT Expr]
          </td>
</tr>
</table>
</div>
<p>
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</p>
<h3 id="lessThan">
<strong>lessThan</strong> - 
    Evaluate the nested body content of this tag if the requested
    variable is less than the specified value.
    </h3>
<div class="indent">
    <p>Compares the variable specified by one of the selector attributes
    against the specified constant value.  The nested body content of this
    tag is evaluated if the variable is <strong>less than</strong>
    the value.</p>
    <table class="tag-attributes">
<thead>
<tr>
<th class="attribute">Attribute Name</th>
<th>Description</th>
</tr>
</thead>
<tr class="evenRow">
<td align="center">cookie</td>
<td>
      <p>The variable to be compared is the value of the cookie whose
      name is specified by this attribute.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="oddRow">
<td align="center">header</td>
<td>
      <p>The variable to be compared is the value of the header whose
      name is specified by this attribute.  The name match is performed
      in a case insensitive manner.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="evenRow">
<td align="center">name</td>
<td>
      <p>The variable to be compared is the JSP bean specified by this
      attribute, if <code>property</code> is not specified, or the value
      of the specified property of this bean, if <code>property</code>
      is specified.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="oddRow">
<td align="center">parameter</td>
<td>
      <p>The variable to be compared is the first, or only, value of the
      request parameter specified by this attribute.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="evenRow">
<td align="center">property</td>
<td>
      <p>The variable to be compared is the property (of the bean specified
      by the <code>name</code> attribute) specified by this attribute.
      The property reference can be simple, nested, and/or indexed.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="oddRow">
<td align="center">scope</td>
<td>
      <p>The bean scope within which to search for the bean named by the
      <code>name</code> property, or "any scope" if not specified.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="evenRow">
<td align="center">value</td>
<td>
      <p>The constant value to which the variable, specified by other
      attribute(s) of this tag, will be compared.</p>
      
            [Required]
          
            [RT Expr]
          </td>
</tr>
</table>
</div>
<p>
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</p>
<h3 id="match">
<strong>match</strong> - 
    Evaluate the nested body content of this tag if the specified value
    is an appropriate substring of the requested variable.
    </h3>
<div class="indent">
    <p>Matches the variable specified by one of the selector attributes
    (as a String) against the specified constant value.  If the value is
    a substring (appropriately limited by the <code>location</code>
    attribute), the nested body content of this tag is evaluated.</p>
    <table class="tag-attributes">
<thead>
<tr>
<th class="attribute">Attribute Name</th>
<th>Description</th>
</tr>
</thead>
<tr class="evenRow">
<td align="center">cookie</td>
<td>
      <p>The variable to be matched is the value of the cookie whose
      name is specified by this attribute.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="oddRow">
<td align="center">header</td>
<td>
      <p>The variable to be matched is the value of the header whose
      name is specified by this attribute.  The name match is performed
      in a case insensitive manner.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="evenRow">
<td align="center">location</td>
<td>
      <p>If not specified, a match between the variable and the value may
      occur at any position within the variable string.  If specified, the
      match must occur at the specified location (either <code>start</code>
      or <code>end</code>) of the variable string.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="oddRow">
<td align="center">name</td>
<td>
      <p>The variable to be matched is the JSP bean specified by this
      attribute, if <code>property</code> is not specified, or the value
      of the specified property of this bean, if <code>property</code>
      is specified.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="evenRow">
<td align="center">parameter</td>
<td>
      <p>The variable to be matched is the first, or only, value of the
      request parameter specified by this attribute.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="oddRow">
<td align="center">property</td>
<td>
      <p>The variable to be matched is the property (of the bean specified
      by the <code>name</code> attribute) specified by this attribute.
      The property reference can be simple, nested, and/or indexed.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="evenRow">
<td align="center">scope</td>
<td>
      <p>The bean scope within which to search for the bean named by the
      <code>name</code> property, or "any scope" if not specified.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="oddRow">
<td align="center">value</td>
<td>
      <p>The constant value which is checked for existence as a substring
      of the specified variable.</p>
      
            [Required]
          
            [RT Expr]
          </td>
</tr>
</table>
</div>
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</p>
<h3 id="messagesNotPresent">
<strong>messagesNotPresent</strong> - 
    Generate the nested body content of this tag if the specified
    message is not present in this request.
    </h3>
<div class="indent">
    <p>Evaluates the nested body content of this tag if
       an <code>ActionMessages</code>
       object, <code>ActionErrors</code> object, a String,
       or a String array is not in request scope.  If
       such a bean is not found, nothing will be rendered.
    </p>
    <p>Since:  Struts 1.1</p>
<table class="tag-attributes">
<thead>
<tr>
<th class="attribute">Attribute Name</th>
<th>Description</th>
</tr>
</thead>
<tr class="evenRow">
<td align="center">name</td>
<td>
      <p>The parameter key to retrieve the message from request scope.</p>
      
            [RT Expr]
          </td>
</tr>
<tr class="oddRow">
<td align="center">property</td>
<td>
      <p>Name of the property for which messages should be
         retrieved.  If not specified, all messages (regardless
         of property) are retrieved.
      </p>
      
            [RT Expr]
          </td>
</tr>
<tr class="evenRow">
<td align="center">message</td>
<td>
      <p>By default the tag will retrieve the request scope bean it will
         iterate over from the <code>Globals.ERROR_KEY</code> constant string,
         but if this attribute is set to 'true' the request scope bean
         will be retrieved from the <code>Globals.MESSAGE_KEY</code>
         constant string.  Also if this is set to 'true', any value
         assigned to the name attribute will be ignored.
      </p>
      
            [RT Expr]
          </td>
</tr>
</table>
</div>
<p>
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</p>
<h3 id="messagesPresent">
<strong>messagesPresent</strong> - 
    Generate the nested body content of this tag if the specified
    message is present in this request.
    </h3>
<div class="indent">
    <p>Evaluates the nested body content of this tag if
       an <code>ActionMessages</code>