org.apache.jasper.el
Class JspValueExpression

java.lang.Object
  javax.el.Expression
      javax.el.ValueExpression
          org.apache.jasper.el.JspValueExpression

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable

public final class JspValueExpression
extends javax.el.ValueExpression
implements java.io.Externalizable

Wrapper for providing context to ValueExpressions

Author:

Jacob Hookom

See Also:

Serialized Form

Constructor Summary

JspValueExpression()

JspValueExpression(java.lang.String mark, javax.el.ValueExpression target)

Method Summary

boolean	equals(java.lang.Object obj) Determines whether the specified object is equal to this Expression.
java.lang.Class<?>	getExpectedType() Returns the type the result of the expression will be coerced to after evaluation.
java.lang.String	getExpressionString() Returns the original String used to create this Expression, unmodified.
java.lang.Class<?>	getType(javax.el.ELContext context) Evaluates the expression relative to the provided context, and returns the most general type that is acceptable for an object to be passed as the value parameter in a future call to the ValueExpression.setValue(javax.el.ELContext, java.lang.Object) method.
java.lang.Object	getValue(javax.el.ELContext context) Evaluates the expression relative to the provided context, and returns the resulting value.
int	hashCode() Returns the hash code for this Expression.
boolean	isLiteralText() Returns whether this expression was created from only literal text.
boolean	isReadOnly(javax.el.ELContext context) Evaluates the expression relative to the provided context, and returns true if a call to ValueExpression.setValue(javax.el.ELContext, java.lang.Object) will always fail.
void	readExternal(java.io.ObjectInput in)
void	setValue(javax.el.ELContext context, java.lang.Object value) Evaluates the expression relative to the provided context, and sets the result to the provided value.
void	writeExternal(java.io.ObjectOutput out)

Methods inherited from class javax.el.ValueExpression

getValueReference

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

JspValueExpression

public JspValueExpression()

JspValueExpression

public JspValueExpression(java.lang.String mark,
                          javax.el.ValueExpression target)

Method Detail

getExpectedType

public java.lang.Class<?> getExpectedType()

Description copied from class: javax.el.ValueExpression

Returns the type the result of the expression will be coerced to after evaluation.

Specified by:

getExpectedType in class javax.el.ValueExpression

Returns:

the expectedType passed to the ExpressionFactory.createValueExpression method that created this ValueExpression.

getType

public java.lang.Class<?> getType(javax.el.ELContext context)
                           throws java.lang.NullPointerException,
                                  javax.el.PropertyNotFoundException,
                                  javax.el.ELException

Description copied from class: javax.el.ValueExpression

Evaluates the expression relative to the provided context, and returns the most general type that is acceptable for an object to be passed as the value parameter in a future call to the ValueExpression.setValue(javax.el.ELContext, java.lang.Object) method.

This is not always the same as getValue().getClass(). For example, in the case of an expression that references an array element, the getType method will return the element type of the array, which might be a superclass of the type of the actual element that is currently in the specified array element.

Specified by:

getType in class javax.el.ValueExpression

Parameters:

context - The context of this evaluation.

Returns:

the most general acceptable type; otherwise undefined.

Throws:

java.lang.NullPointerException - if context is null.

javax.el.PropertyNotFoundException - if one of the property resolutions failed because a specified variable or property does not exist or is not readable.

javax.el.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.

isReadOnly

public boolean isReadOnly(javax.el.ELContext context)
                   throws java.lang.NullPointerException,
                          javax.el.PropertyNotFoundException,
                          javax.el.ELException

Description copied from class: javax.el.ValueExpression

Evaluates the expression relative to the provided context, and returns true if a call to ValueExpression.setValue(javax.el.ELContext, java.lang.Object) will always fail.

Specified by:

isReadOnly in class javax.el.ValueExpression

Parameters:

context - The context of this evaluation.

Returns:

true if the expression is read-only or false if not.

Throws:

java.lang.NullPointerException - if context is null.

javax.el.PropertyNotFoundException - if one of the property resolutions failed because a specified variable or property does not exist or is not readable.

javax.el.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. * @throws NullPointerException if context is null

setValue

public void setValue(javax.el.ELContext context,
                     java.lang.Object value)
              throws java.lang.NullPointerException,
                     javax.el.PropertyNotFoundException,
                     javax.el.PropertyNotWritableException,
                     javax.el.ELException

Description copied from class: javax.el.ValueExpression

Evaluates the expression relative to the provided context, and sets the result to the provided value.

Specified by:

setValue in class javax.el.ValueExpression

Parameters:

context - The context of this evaluation.

value - The new value to be set.

Throws:

java.lang.NullPointerException - if context is null.

javax.el.PropertyNotFoundException - if one of the property resolutions failed because a specified variable or property does not exist or is not readable.

javax.el.PropertyNotWritableException - if the final variable or property resolution failed because the specified variable or property is not writable.

javax.el.ELException - if an exception was thrown while attempting to set the property or variable. The thrown exception must be included as the cause property of this exception, if available.

getValue

public java.lang.Object getValue(javax.el.ELContext context)
                          throws java.lang.NullPointerException,
                                 javax.el.PropertyNotFoundException,
                                 javax.el.ELException

Description copied from class: javax.el.ValueExpression

Evaluates the expression relative to the provided context, and returns the resulting value.

The resulting value is automatically coerced to the type returned by getExpectedType(), which was provided to the ExpressionFactory when this expression was created.

Specified by:

getValue in class javax.el.ValueExpression

Parameters:

context - The context of this evaluation.

Returns:

The result of the expression evaluation.

Throws:

java.lang.NullPointerException - if context is null.

javax.el.PropertyNotFoundException - if one of the property resolutions failed because a specified variable or property does not exist or is not readable.

javax.el.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.

equals

public boolean equals(java.lang.Object obj)

Description copied from class: javax.el.Expression

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.

Specified by:

equals in class javax.el.Expression

Parameters:

obj - the Object to test for equality.

Returns:

true if obj equals this Expression; false otherwise.

See Also:

Hashtable, Object.equals(java.lang.Object)

hashCode

public int hashCode()

Description copied from class: javax.el.Expression

Returns the hash code for this Expression.

See the note in the Expression.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 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.

Specified by:

hashCode in class javax.el.Expression

Returns:

The hash code for this Expression.

See Also:

Expression.equals(java.lang.Object), Hashtable, Object.hashCode()

getExpressionString

public java.lang.String getExpressionString()

Description copied from class: javax.el.Expression

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.

Specified by:

getExpressionString in class javax.el.Expression

Returns:

The original expression String.

isLiteralText

public boolean isLiteralText()

Description copied from class: javax.el.Expression

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 #{...}).

Specified by:

isLiteralText in class javax.el.Expression

Returns:

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

writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException

Specified by:

writeExternal in interface java.io.Externalizable

Throws:

java.io.IOException

readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException

Specified by:

readExternal in interface java.io.Externalizable

Throws:

java.io.IOException

java.lang.ClassNotFoundException