Class MethodExpressionImpl
- java.lang.Object
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- javax.el.Expression
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- javax.el.MethodExpression
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- org.apache.el.MethodExpressionImpl
 
 
 
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- All Implemented Interfaces:
- java.io.Externalizable,- java.io.Serializable
 
 public final class MethodExpressionImpl extends MethodExpression implements java.io.Externalizable AnExpressionthat refers to a method on an object.The ExpressionFactory.createMethodExpression(javax.el.ELContext, java.lang.String, java.lang.Class<?>, java.lang.Class<?>[])method can be used to parse an expression string and return a concrete instance ofMethodExpressionthat encapsulates the parsed expression. TheFunctionMapperis used at parse time, not evaluation time, so one is not needed to evaluate an expression using this class. However, theELContextis needed at evaluation time.The getMethodInfo(javax.el.ELContext)andinvoke(javax.el.ELContext, java.lang.Object[])methods will evaluate the expression each time they are called. TheELResolverin theELContextis used to resolve the top-level variables and to determine the behavior of the.and[]operators. For any of the two methods, theELResolver.getValue(javax.el.ELContext, java.lang.Object, java.lang.Object)method is used to resolve all properties up to but excluding the last one. This provides thebaseobject on which the method appears. If thebaseobject is null, aNullPointerExceptionmust be thrown. At the last resolution, the finalpropertyis then coerced to aString, which provides the name of the method to be found. A method matching the name and expected parameters provided at parse time is found and it is either queried or invoked (depending on the method called on thisMethodExpression).See the notes about comparison, serialization and immutability in the Expressionjavadocs.- Author:
- Jacob Hookom [jacob@hookom.net]
- See Also:
- ELResolver,- Expression,- ExpressionFactory,- MethodExpression, Serialized Form
 
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Constructor SummaryConstructors Constructor Description MethodExpressionImpl()MethodExpressionImpl(java.lang.String expr, org.apache.el.parser.Node node, FunctionMapper fnMapper, VariableMapper varMapper, java.lang.Class<?> expectedType, java.lang.Class<?>[] paramTypes)
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Method SummaryAll Methods Instance Methods Concrete Methods Modifier and Type Method Description booleanequals(java.lang.Object obj)Determines whether the specified object is equal to thisExpression.java.lang.StringgetExpressionString()Returns the original String used to create thisExpression, unmodified.MethodInfogetMethodInfo(ELContext context)Evaluates the expression relative to the provided context, and returns information about the actual referenced method.inthashCode()Returns the hash code for thisExpression.java.lang.Objectinvoke(ELContext context, java.lang.Object[] params)Evaluates the expression relative to the provided context, invokes the method that was found using the supplied parameters, and returns the result of the method invocation.booleanisLiteralText()booleanisParametersProvided()booleanisParmetersProvided()voidreadExternal(java.io.ObjectInput in)voidwriteExternal(java.io.ObjectOutput out)
 
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Constructor Detail- 
MethodExpressionImplpublic MethodExpressionImpl() 
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MethodExpressionImplpublic MethodExpressionImpl(java.lang.String expr, org.apache.el.parser.Node node, FunctionMapper fnMapper, VariableMapper varMapper, java.lang.Class<?> expectedType, java.lang.Class<?>[] paramTypes)
 
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Method Detail- 
equalspublic boolean equals(java.lang.Object obj) Determines whether the specified object is equal to thisExpression.The result is trueif and only if the argument is notnull, is anExpressionobject that is the of the same type (ValueExpressionorMethodExpression), and has an identical parsed representation.Note that two expressions can be equal if their expression Strings are different. For example, ${fn1:foo()}and${fn2:foo()}are equal if their correspondingFunctionMappers mappedfn1:fooandfn2:footo the same method.- Specified by:
- equalsin class- Expression
- Parameters:
- obj- the- Objectto test for equality.
- Returns:
- trueif- objequals this- Expression;- falseotherwise.
- See Also:
- Hashtable,- Object.equals(java.lang.Object)
 
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getExpressionStringpublic java.lang.String getExpressionString() Returns the original String used to create thisExpression, unmodified.This is used for debugging purposes but also for the purposes of comparison (e.g. to ensure the expression in a configuration file has not changed). This method does not provide sufficient information to re-create an expression. Two different expressions can have exactly the same expression string but different function mappings. Serialization should be used to save and restore the state of an Expression.- Specified by:
- getExpressionStringin class- Expression
- Returns:
- The original expression String.
- See Also:
- Expression.getExpressionString()
 
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getMethodInfopublic MethodInfo getMethodInfo(ELContext context) throws PropertyNotFoundException, MethodNotFoundException, ELException Evaluates the expression relative to the provided context, and returns information about the actual referenced method.- Specified by:
- getMethodInfoin class- MethodExpression
- Parameters:
- context- The context of this evaluation
- Returns:
- an instance of MethodInfocontaining information about the method the expression evaluated to.
- Throws:
- java.lang.NullPointerException- if context is- nullor the base object is- nullon the last resolution.
- PropertyNotFoundException- if one of the property resolutions failed because a specified variable or property does not exist or is not readable.
- MethodNotFoundException- if no suitable method can be found.
- ELException- if an exception was thrown while performing property or variable resolution. The thrown exception must be included as the cause property of this exception, if available.
- See Also:
- MethodExpression.getMethodInfo(javax.el.ELContext)
 
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hashCodepublic int hashCode() Returns the hash code for thisExpression.See the note in the equals(java.lang.Object)method on how two expressions can be equal if their expression Strings are different. Recall that if two objects are equal according to theequals(Object)method, then calling thehashCodemethod on each of the two objects must produce the same integer result. Implementations must take special note and implementhashCodecorrectly.- Specified by:
- hashCodein class- Expression
- Returns:
- The hash code for this Expression.
- See Also:
- equals(java.lang.Object),- Hashtable,- Object.hashCode()
 
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invokepublic java.lang.Object invoke(ELContext context, java.lang.Object[] params) throws PropertyNotFoundException, MethodNotFoundException, ELException Evaluates the expression relative to the provided context, invokes the method that was found using the supplied parameters, and returns the result of the method invocation.- Specified by:
- invokein class- MethodExpression
- Parameters:
- context- The context of this evaluation.
- params- The parameters to pass to the method, or- nullif no parameters.
- Returns:
- the result of the method invocation (nullif the method has avoidreturn type).
- Throws:
- java.lang.NullPointerException- if context is- nullor the base object is- nullon the last resolution.
- PropertyNotFoundException- if one of the property resolutions failed because a specified variable or property does not exist or is not readable.
- MethodNotFoundException- if no suitable method can be found.
- ELException- if an exception was thrown while performing property or variable resolution. The thrown exception must be included as the cause property of this exception, if available. If the exception thrown is an- InvocationTargetException, extract its- causeand pass it to the- ELExceptionconstructor.
- See Also:
- MethodExpression.invoke(javax.el.ELContext, java.lang.Object[])
 
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readExternalpublic void readExternal(java.io.ObjectInput in) throws java.io.IOException, java.lang.ClassNotFoundException- Specified by:
- readExternalin interface- java.io.Externalizable
- Throws:
- java.io.IOException
- java.lang.ClassNotFoundException
 
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writeExternalpublic void writeExternal(java.io.ObjectOutput out) throws java.io.IOException- Specified by:
- writeExternalin interface- java.io.Externalizable
- Throws:
- java.io.IOException
 
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isLiteralTextpublic boolean isLiteralText() - Specified by:
- isLiteralTextin class- Expression
 
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isParametersProvidedpublic boolean isParametersProvided() - Overrides:
- isParametersProvidedin class- MethodExpression
- Returns:
- This default implementation always returns false
- Since:
- EL 3.0
 
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isParmetersProvidedpublic boolean isParmetersProvided() - Overrides:
- isParmetersProvidedin class- MethodExpression
- Returns:
- Always false
- Since:
- EL 2.2 Note: The spelling mistake is deliberate. isParmetersProvided() - Specification definition isParametersProvided() - Corrected spelling
 
 
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