Class BSHExpression

  extended by org.pentaho.reporting.engine.classic.core.function.AbstractExpression
      extended by org.pentaho.reporting.engine.classic.core.modules.misc.beanshell.BSHExpression
All Implemented Interfaces:
Serializable, Cloneable, Expression

public class BSHExpression
extends AbstractExpression

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:

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.pentaho.reporting.engine.classic.core.*;

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 site for more information ... // // A return value of type "Object" is alway implied ... getValue () { return userdefinedFunction ("Hello World :) ", new Date()); }

Thomas Morgner
See Also:
Serialized Form

Field Summary
          The headerfile with the default initialisations.
Constructor Summary
          default constructor, create a new BeanShellExpression.
Method Summary
 String getExpression()
          Sets the beanshell script as string.
 Expression getInstance()
          Return a new instance of this expression.
 Object getValue()
          Evaluates the defined expression.
 void setExpression(String expression)
          Sets the beanshell script that should be executed.
Methods inherited from class org.pentaho.reporting.engine.classic.core.function.AbstractExpression
clone, getDataRow, getDependencyLevel, getName, getReportConfiguration, getResourceBundleFactory, getRuntime, isActive, isDeepTraversing, isPreserve, setActive, setDependencyLevel, setName, setPreserve, setRuntime
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail


public static final String BSHHEADERFILE
The headerfile with the default initialisations.

See Also:
Constant Field Values
Constructor Detail


public BSHExpression()
default constructor, create a new BeanShellExpression.

Method Detail


public 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.

the evaluated value or null.


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
getInstance in class AbstractExpression
a copy of this function.


public String getExpression()
Sets the beanshell script as string.

the script.


public void setExpression(String expression)
Sets the beanshell script that should be executed. The script should define a getValue() method which returns a single object.

expression - the script.