org.jfree.report.modules.misc.beanshell
Class BSHExpression

java.lang.Object
  org.jfree.report.function.AbstractExpression
      org.jfree.report.modules.misc.beanshell.BSHExpression

All Implemented Interfaces:

java.lang.Cloneable, Expression, java.io.Serializable

public class BSHExpression

extends AbstractExpression

implements java.io.Serializable

An expression that uses the BeanShell scripting framework to perform a scripted calculation. The expression itself is contained in a function called

Object getValue()

and this function is defined in the expression property. You have to overwrite the function getValue() to begin and to end your expression, but you are free to add your own functions to the script.

By default, base Java core and extension packages are imported for you. They are:

• java.lang
• java.io
• java.util
• java.net
• java.awt
• java.awt.event
• javax.swing
• javax.swing.event

An example in the XML format: (from report1.xml)

 
 
 // you may import packages and classes or use the fully qualified name of the class
 import org.jfree.report.*;

 String userdefinedFunction (String parameter, Date date)
 {
 return parameter + " - the current date is " + date);
 }

 // use simple java code to perform the expression. You may use all classes
 // available in your classpath as if you write "real" java code in your favourite
 // IDE.
 // See the www.beanshell.org site for more information ...
 //
 // A return value of type "Object" is alway implied ...
 getValue ()
 {
 return userdefinedFunction ("Hello World :) ", new Date());
 }
 
 
 

Author:

Thomas Morgner

See Also:

Serialized Form

Field Summary

static java.lang.String

BSHHEADERFILE The headerfile with the default initialisations.

Fields inherited from interface org.jfree.report.function.Expression

AUTOACTIVATE_PROPERTY

Constructor Summary

BSHExpression()
default constructor, create a new BeanShellExpression.

Method Summary

java.lang.Object	clone() Clones the expression and reinitializes the script.
Expression	getInstance() Return a new instance of this expression.
java.lang.Object	getValue() Evaluates the defined expression.
void	initialize() Initializes the expression by executing the header file and the expression.

Methods inherited from class org.jfree.report.function.AbstractExpression

getDataRow, getDependencyLevel, getName, getProperties, getProperty, getProperty, isActive, setDataRow, setDependencyLevel, setName, setProperties, setProperty

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BSHHEADERFILE

public static final java.lang.String BSHHEADERFILE

The headerfile with the default initialisations.

See Also:

Constant Field Values

Constructor Detail

BSHExpression

public BSHExpression()

default constructor, create a new BeanShellExpression.

Method Detail

getValue

public java.lang.Object getValue()

Evaluates the defined expression. If an exception or an evaluation error occures, the evaluation returns null and the error is logged. The current datarow and a copy of the expressions properties are set to script-internal variables. Changes to the properties will not alter the expressions original properties and will be lost when the evaluation is finished.

Expressions do not maintain a state and no assumptions about the order of evaluation can be made.

Specified by:

getValue in interface Expression

Returns:

the evaluated value or null.

initialize

public void initialize()
                throws FunctionInitializeException

Initializes the expression by executing the header file and the expression. The expression should not call getValue() by itself, as the dataRow and the properties are not initialized yet.

Initialisations of the script can be put at the end of the script:

   ...
   
   ...
   getValue ()
   {
   return userdefinedFunction ("Hello World :) ", new Date());
   }
   ...

   // script initialisations here
   System.out.println ("Script initialized @ " + new Date());
   
   ...
   

Specified by:

initialize in interface Expression

Overrides:

initialize in class AbstractExpression

Throws:

FunctionInitializeException - if the expression has not been initialized correctly.

clone

public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException

Clones the expression and reinitializes the script.

Specified by:

clone in interface Expression

Overrides:

clone in class AbstractExpression

Returns:

a clone of the expression.

Throws:

java.lang.CloneNotSupportedException - this should never happen.

getInstance

public Expression getInstance()

Return a new instance of this expression. The copy is initialized and uses the same parameters as the original, but does not share any objects.

Specified by:

getInstance in interface Expression

Overrides:

getInstance in class AbstractExpression

Returns:

a copy of this function.