Jakarta Expression Language 3.0 Implementation 3.0.4 · com.sun.el.MethodExpressionImpl

An Expression that refers to a method on an object.

The ExpressionFactory#createMethodExpression method can be used to parse an expression string and return a concrete instance of MethodExpression that encapsulates the parsed expression. The FunctionMapper is used at parse time, not evaluation time, so one is not needed to evaluate an expression using this class. However, the ELContext is needed at evaluation time.

The getMethodInfo and invoke methods will evaluate the expression each time they are called. The ELResolver in the ELContext is used to resolve the top-level variables and to determine the behavior of the . and [] operators. For any of the two methods, the ELResolver#getValue method is used to resolve all properties up to but excluding the last one. This provides the base object on which the method appears. If the base object is null, a NullPointerException must be thrown. At the last resolution, the final property is then coerced to a String, 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 this MethodExpression).

See the notes about comparison, serialization and immutability in the Expression javadocs.

Field Summary

Modifier and Type	Field and Description
private Class<?>	expectedType
private String	expr
private FunctionMapper	fnMapper
private transient Node	node
private Class<?>[]	paramTypes
private VariableMapper	varMapper

Constructor Summary

Access	Constructor and Description
public	MethodExpressionImpl()
public	MethodExpressionImpl(String the expression expr, Node the node node, FunctionMapper the function mapper fnMapper, VariableMapper the variable mapper varMapper, Class<?> expected return type of method expectedType, Class<?>[] the method parameters paramTypes)

Method Summary

Modifier and Type	Method and Description
public boolean	Returns: `true` if `obj` equals this `Expression`; `false` otherwise. equals(Object the `Object` to test for equality. obj) Implements abstract javax.el.Expression.equals. Determines whether the specified object is equal to this `Expression`.
public String	Returns: The original expression String. getExpressionString() Implements abstract javax.el.Expression.getExpressionString. Returns the original String used to create this `Expression`, unmodified.
public MethodInfo	Returns: an instance of `MethodInfo` containing information about the method the expression evaluated to. getMethodInfo(ELContext The context of this evaluation context) Implements abstract javax.el.MethodExpression.getMethodInfo. Evaluates the expression relative to the provided context, and returns information about the actual referenced method.
private Node	Returns: The Node for the expression getNode()
public int	Returns: The hash code for this `Expression`. hashCode() Implements abstract javax.el.Expression.hashCode. Returns the hash code for this `Expression`.
public Object	Returns: the result of the method invocation (`null` if the method has a `void` return type). invoke(ELContext The context of this evaluation. context, Object[] The parameters to pass to the method, or `null` if no parameters. params) Implements abstract javax.el.MethodExpression.invoke. 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.
public boolean	isLiteralText() Implements abstract javax.el.Expression.isLiteralText. Returns whether this expression was created from only literal text.
public boolean	isParametersProvided() Overrides javax.el.MethodExpression.isParametersProvided. Return whether this MethodExpression was created with parameters.
public void	readExternal(ObjectInput the stream to read data from in order to restore the object in) Implements java.io.Externalizable.readExternal. The object implements the readExternal method to restore its contents by calling the methods of DataInput for primitive types and readObject for objects, strings and arrays.
public void	writeExternal(ObjectOutput the stream to write the object to out) Implements java.io.Externalizable.writeExternal. The object implements the writeExternal method to save its contents by calling the methods of DataOutput for its primitive values or calling the writeObject method of ObjectOutput for objects, strings, and arrays.

Inherited from javax.el.MethodExpression:: isParmetersProvided

Field Detail

expectedType	back to summary
private Class<?> expectedType

expr	back to summary
private String expr

fnMapper	back to summary
private FunctionMapper fnMapper

node	back to summary
private transient Node node

paramTypes	back to summary
private Class<?>[] paramTypes

varMapper	back to summary
private VariableMapper varMapper

Constructor Detail

MethodExpressionImpl	back to summary
public MethodExpressionImpl()

MethodExpressionImpl	back to summary
public MethodExpressionImpl(String expr, Node node, FunctionMapper fnMapper, VariableMapper varMapper, Class<?> expectedType, Class<?>[] paramTypes) Parameters expr:String the expression node:Node the node fnMapper:FunctionMapper the function mapper varMapper:VariableMapper the variable mapper expectedType:Class<?> expected return type of method paramTypes:Class<?>[] the method parameters

Method Detail

equals back to summary

equals	back to summary
public boolean equals(Object obj) Implements abstract javax.el.Expression.equals. Determines whether the specified object is equal to this `Expression`. The result is `true` if and only if the argument is not `null`, is an `Expression` object that is the of the same type (`ValueExpression` or `MethodExpression`), 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 corresponding `FunctionMapper`s mapped `fn1:foo` and `fn2:foo` to the same method. Parameters obj:Object the `Object` to test for equality. Returns:boolean `true` if `obj` equals this `Expression`; `false` otherwise. Annotations @Override See Also `java.util.Hashtable`, `java.lang.Object#equals(java.lang.Object)`

public boolean equals(Object obj)

Implements abstract javax.el.Expression.equals.

Determines whether the specified object is equal to this Expression.

The result is true if and only if the argument is not null, is an Expression object that is the of the same type (ValueExpression or MethodExpression), 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 corresponding FunctionMappers mapped fn1:foo and fn2:foo to the same method.

Parameters

obj:Object: the Object to test for equality.

Returns:boolean

true if obj equals this Expression; false otherwise.

Annotations

@Override

getExpressionString back to summary

getExpressionString	back to summary
public String getExpressionString() Implements abstract javax.el.Expression.getExpressionString. Returns the original String used to create this `Expression`, 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`. Returns:String The original expression String. Annotations @Override See Also `javax.el.Expression#getExpressionString()`

public String getExpressionString()

Implements abstract javax.el.Expression.getExpressionString.

Returns the original String used to create this Expression, 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.

Returns:String

The original expression String.

Annotations

@Override

getMethodInfo back to summary

getMethodInfo	back to summary
public MethodInfo getMethodInfo(ELContext context) throws PropertyNotFoundException, MethodNotFoundException, ELException Implements abstract javax.el.MethodExpression.getMethodInfo. Evaluates the expression relative to the provided context, and returns information about the actual referenced method. Parameters context:ELContext The context of this evaluation Returns:MethodInfo an instance of `MethodInfo` containing information about the method the expression evaluated to. Annotations @Override Exceptions 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. NullPointerException: if context is `null` or the base object is `null` on the last resolution. See Also `javax.el.MethodExpression#getMethodInfo(javax.el.ELContext)`

public MethodInfo getMethodInfo(ELContext context) throws PropertyNotFoundException, MethodNotFoundException, ELException

Implements abstract javax.el.MethodExpression.getMethodInfo.

Evaluates the expression relative to the provided context, and returns information about the actual referenced method.

Parameters

context:ELContext: The context of this evaluation

Returns:MethodInfo

an instance of MethodInfo containing information about the method the expression evaluated to.

Annotations

@Override

Exceptions

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.
NullPointerException:: if context is null or the base object is null on the last resolution.

getNode	back to summary
private Node getNode() throws ELException Returns:Node The Node for the expression

hashCode back to summary

hashCode	back to summary
public int hashCode() Implements abstract javax.el.Expression.hashCode. Returns the hash code for this `Expression`. See the note in the `equals` method on how two expressions can be equal if their expression Strings are different. Recall that if two objects are equal according to the `equals(Object)` method, then calling the `hashCode` method on each of the two objects must produce the same integer result. Implementations must take special note and implement `hashCode` correctly. Returns:int The hash code for this `Expression`. Annotations @Override See Also `equals`, `java.util.Hashtable`, `java.lang.Object#hashCode()`

public int hashCode()

Implements abstract javax.el.Expression.hashCode.

Returns the hash code for this Expression.

See the note in the equals method on how two expressions can be equal if their expression Strings are different. Recall that if two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result. Implementations must take special note and implement hashCode correctly.

Returns:int

The hash code for this Expression.

Annotations

@Override

invoke back to summary

invoke	back to summary
public Object invoke(ELContext context, Object[] params) throws PropertyNotFoundException, MethodNotFoundException, ELException Implements abstract javax.el.MethodExpression.invoke. 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. Parameters context:ELContext The context of this evaluation. params:Object[] The parameters to pass to the method, or `null` if no parameters. Returns:Object the result of the method invocation (`null` if the method has a `void` return type). Annotations @Override Exceptions 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 `cause` and pass it to the `ELException` constructor. NullPointerException: if context is `null` or the base object is `null` on the last resolution. See Also `javax.el.MethodExpression#invoke(javax.el.ELContext, java.lang.Object[])`

public Object invoke(ELContext context, Object[] params) throws PropertyNotFoundException, MethodNotFoundException, ELException

Implements abstract javax.el.MethodExpression.invoke.

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.

Parameters

context:ELContext: The context of this evaluation.
params:Object[]: The parameters to pass to the method, or null if no parameters.

Returns:Object

the result of the method invocation (null if the method has a void return type).

Annotations

@Override

Exceptions

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 cause and pass it to the ELException constructor.
NullPointerException:: if context is null or the base object is null on the last resolution.

isLiteralText back to summary

isLiteralText	back to summary
public boolean isLiteralText() Implements abstract javax.el.Expression.isLiteralText. Doc from javax.el.Expression.isLiteralText. Returns whether this expression was created from only literal text. This method must return `true` if and only if the expression string this expression was created from contained no unescaped EL delimeters (`${...}` or `#{...}`). Returns:boolean `true` if this expression was created from only literal text; `false` otherwise. Annotations @Override

public boolean isLiteralText()

Implements abstract javax.el.Expression.isLiteralText.

Doc from javax.el.Expression.isLiteralText.

Returns whether this expression was created from only literal text.

This method must return true if and only if the expression string this expression was created from contained no unescaped EL delimeters (${...} or #{...}).

Returns:boolean

true if this expression was created from only literal text; false otherwise.

Annotations

@Override

isParametersProvided back to summary

isParametersProvided	back to summary
public boolean isParametersProvided() Overrides javax.el.MethodExpression.isParametersProvided. Doc from javax.el.MethodExpression.isParametersProvided. Return whether this MethodExpression was created with parameters. This method must return `true` if and only if parameters are specified in the EL, using the expr-a.expr-b(...) syntax. Returns:boolean `true` if the MethodExpression was created with parameters, `false` otherwise. Annotations @Override

public boolean isParametersProvided()

Overrides javax.el.MethodExpression.isParametersProvided.

Doc from javax.el.MethodExpression.isParametersProvided.

Return whether this MethodExpression was created with parameters.

This method must return true if and only if parameters are specified in the EL, using the expr-a.expr-b(...) syntax.

Returns:boolean

true if the MethodExpression was created with parameters, false otherwise.

Annotations

@Override

readExternal	back to summary
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException Implements java.io.Externalizable.readExternal. Doc from java.io.Externalizable.readExternal. The object implements the readExternal method to restore its contents by calling the methods of DataInput for primitive types and readObject for objects, strings and arrays. The readExternal method must read the values in the same sequence and with the same types as were written by writeExternal. Parameters in:ObjectInput the stream to read data from in order to restore the object Annotations @Override Exceptions IOException: if I/O errors occur ClassNotFoundException: If the class for an object being restored cannot be found.

readExternal

back to summary

public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException

Implements java.io.Externalizable.readExternal.

Doc from java.io.Externalizable.readExternal.

The object implements the readExternal method to restore its contents by calling the methods of DataInput for primitive types and readObject for objects, strings and arrays. The readExternal method must read the values in the same sequence and with the same types as were written by writeExternal.

Parameters

in:ObjectInput: the stream to read data from in order to restore the object

Annotations

@Override

Exceptions

IOException:: if I/O errors occur
ClassNotFoundException:: If the class for an object being restored cannot be found.

writeExternal	back to summary
public void writeExternal(ObjectOutput out) throws IOException Implements java.io.Externalizable.writeExternal. Doc from java.io.Externalizable.writeExternal. The object implements the writeExternal method to save its contents by calling the methods of DataOutput for its primitive values or calling the writeObject method of ObjectOutput for objects, strings, and arrays. Parameters out:ObjectOutput the stream to write the object to Annotations @Override Exceptions IOException: Includes any I/O exceptions that may occur

writeExternal

back to summary

public void writeExternal(ObjectOutput out) throws IOException

Implements java.io.Externalizable.writeExternal.

Doc from java.io.Externalizable.writeExternal.

The object implements the writeExternal method to save its contents by calling the methods of DataOutput for its primitive values or calling the writeObject method of ObjectOutput for objects, strings, and arrays.

Parameters

out:ObjectOutput: the stream to write the object to

Annotations

@Override

Exceptions

IOException:: Includes any I/O exceptions that may occur

public final Class MethodExpressionImpl

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail