Interface TagPluginContext
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public interface TagPluginContext
This interface allows the plugin author to make inquiries about the properties of the current tag, and to use Jasper resources to generate direct Java codes in place of tag handler invocations.
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description void
dontUseTagPlugin()
Abandon optimization for this tag handler, and instruct Jasper to generate the tag handler calls, as usual.void
generateAttribute(java.lang.String attribute)
Generate codes to evaluate value of a attribute in the custom tag The codes is a Java expression.void
generateBody()
Generate codes for the body of the custom tagvoid
generateDeclaration(java.lang.String id, java.lang.String text)
Generate a declaration in the of the generated class.void
generateImport(java.lang.String s)
Generate an import statementvoid
generateJavaSource(java.lang.String s)
Generate Java source code scriptletjava.lang.String
getConstantAttribute(java.lang.String attribute)
TagPluginContext
getParentContext()
Get the PluginContext for the parent of this custom tag.java.lang.Object
getPluginAttribute(java.lang.String attr)
Get the value of an attribute in the current tagplugin context.java.lang.String
getTemporaryVariableName()
boolean
isAttributeSpecified(java.lang.String attribute)
boolean
isConstantAttribute(java.lang.String attribute)
boolean
isScriptless()
boolean
isTagFile()
Is the tag being used inside a tag file?void
setPluginAttribute(java.lang.String attr, java.lang.Object value)
Associate the attribute with a value in the current tagplugin context.
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Method Detail
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isScriptless
boolean isScriptless()
- Returns:
- true if the body of the tag is scriptless.
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isAttributeSpecified
boolean isAttributeSpecified(java.lang.String attribute)
- Parameters:
attribute
- Name of the attribute- Returns:
- true if the attribute is specified in the tag
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getTemporaryVariableName
java.lang.String getTemporaryVariableName()
- Returns:
- A unique temporary variable name that the plugin can use.
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generateImport
void generateImport(java.lang.String s)
Generate an import statement- Parameters:
s
- Name of the import class, '*' allowed.
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generateDeclaration
void generateDeclaration(java.lang.String id, java.lang.String text)
Generate a declaration in the of the generated class. This can be used to declare an inner class, a method, or a class variable.- Parameters:
id
- A unique ID identifying the declaration. It is not part of the declaration, and is used to ensure that the declaration will only appear once. If this method is invoked with the same id more than once in the translation unit, only the first declaration will be taken.text
- The text of the declaration.
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generateJavaSource
void generateJavaSource(java.lang.String s)
Generate Java source code scriptlet- Parameters:
s
- the scriptlet (raw Java source)
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isConstantAttribute
boolean isConstantAttribute(java.lang.String attribute)
- Parameters:
attribute
- The attribute name- Returns:
- true if the attribute is specified and its value is a translation-time constant.
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getConstantAttribute
java.lang.String getConstantAttribute(java.lang.String attribute)
- Parameters:
attribute
- The attribute name- Returns:
- A string that is the value of a constant attribute. Undefined if the attribute is not a (translation-time) constant. null if the attribute is not specified.
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generateAttribute
void generateAttribute(java.lang.String attribute)
Generate codes to evaluate value of a attribute in the custom tag The codes is a Java expression. NOTE: Currently cannot handle attributes that are fragments.- Parameters:
attribute
- The specified attribute
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generateBody
void generateBody()
Generate codes for the body of the custom tag
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dontUseTagPlugin
void dontUseTagPlugin()
Abandon optimization for this tag handler, and instruct Jasper to generate the tag handler calls, as usual. Should be invoked if errors are detected, or when the tag body is deemed too complicated for optimization.
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getParentContext
TagPluginContext getParentContext()
Get the PluginContext for the parent of this custom tag. NOTE: The operations available for PluginContext so obtained is limited to getPluginAttribute and setPluginAttribute, and queries (e.g. isScriptless(). There should be no calls to generate*().- Returns:
- The pluginContext for the parent node. null if the parent is not a custom tag, or if the pluginContext if not available (because useTagPlugin is false, e.g).
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setPluginAttribute
void setPluginAttribute(java.lang.String attr, java.lang.Object value)
Associate the attribute with a value in the current tagplugin context. The plugin attributes can be used for communication among tags that must work together as a group. See <c:when> for an example.- Parameters:
attr
- The attribute namevalue
- The attribute value
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getPluginAttribute
java.lang.Object getPluginAttribute(java.lang.String attr)
Get the value of an attribute in the current tagplugin context.- Parameters:
attr
- The attribute name- Returns:
- the attribute value
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isTagFile
boolean isTagFile()
Is the tag being used inside a tag file?- Returns:
true
if inside a tag file
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