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package javax.faces.event;
import javax.el.ELContext;
import javax.el.ELException;
import javax.el.MethodExpression;
import javax.faces.context.FacesContext;
import javax.faces.component.StateHolder;
import java.util.logging.Logger;
import javax.el.MethodNotFoundException;
/**
* MethodExpressionActionListener
* is an {@link ActionListener} that wraps a {@link
* MethodExpression}. When it receives a {@link ActionEvent}, it
* executes a method on an object identified by the {@link
* MethodExpression}.
*/
public class MethodExpressionActionListener implements ActionListener,
StateHolder {
private static final Logger LOGGER =
Logger.getLogger("javax.faces.event", "javax.faces.LogStrings");
// ------------------------------------------------------ Instance Variables
private MethodExpression methodExpressionOneArg = null;
private MethodExpression methodExpressionZeroArg = null;
private boolean isTransient;
private final static Class[] ACTION_LISTENER_ZEROARG_SIG = new Class[] { };
public MethodExpressionActionListener() { }
/**
* Construct a {@link ValueChangeListener} that
* contains a {@link MethodExpression}. To accomodate method expression targets
* that take no arguments instead of taking an {@link ActionEvent}
* argument, the implementation of this class must take the
* argument methodExpressionOneArg, extract its
* expression string, and create another
* MethodExpression whose expected param types match
* those of a zero argument method. The usage requirements for both
* of these MethodExpression instances are described in
* {@link #processAction}.
*
* @param methodExpressionOneArg a MethodExpression
* that points to a method that returns void and takes
* a single argument of type {@link ActionEvent}.
*/
public MethodExpressionActionListener(MethodExpression methodExpressionOneArg) {
super();
this.methodExpressionOneArg = methodExpressionOneArg;
FacesContext context = FacesContext.getCurrentInstance();
ELContext elContext = context.getELContext();
this.methodExpressionZeroArg = context.getApplication().
getExpressionFactory().createMethodExpression(elContext,
methodExpressionOneArg.getExpressionString(), Void.class,
ACTION_LISTENER_ZEROARG_SIG);
}
public MethodExpressionActionListener(MethodExpression methodExpressionOneArg,
MethodExpression methodExpressionZeroArg) {
super();
this.methodExpressionOneArg = methodExpressionOneArg;
this.methodExpressionZeroArg = methodExpressionZeroArg;
}
// ------------------------------------------------------- Event Method
/**
* Call through to the {@link
* MethodExpression} passed in our constructor. First, try to invoke the
* MethodExpression passed to the constructor of this
* instance, passing the argument {@link ActionEvent} as the
* argument. If a {@link MethodNotFoundException} is thrown, call
* to the zero argument MethodExpression derived from
* the MethodExpression passed to the constructor of
* this instance. If that
* fails for any reason, throw an {@link AbortProcessingException},
* including the cause of the failure.
*
* @throws NullPointerException {@inheritDoc}
* @throws AbortProcessingException {@inheritDoc}
*/
@Override
public void processAction(ActionEvent actionEvent) throws AbortProcessingException {
if (actionEvent == null) {
throw new NullPointerException();
}
FacesContext context = FacesContext.getCurrentInstance();
ELContext elContext = context.getELContext();
try {
try {
methodExpressionOneArg.invoke(elContext, new Object[] {actionEvent});
} catch (MethodNotFoundException mnfe) {
methodExpressionZeroArg.invoke(elContext, new Object[]{});
}
} catch (ELException ee) {
if (ee.getCause() instanceof AbortProcessingException) {
throw (AbortProcessingException) ee.getCause();
} else {
throw (ELException) ee;
}
}
}
// ------------------------------------------------ Methods from StateHolder
/**
* Both {@link MethodExpression}
* instances described in the constructor must be saved.
*/
@Override
public Object saveState(FacesContext context) {
if (context == null) {
throw new NullPointerException();
}
return new Object[] { methodExpressionOneArg, methodExpressionZeroArg };
}
/**
* Both {@link MethodExpression}
* instances described in the constructor must be restored.
*/
@Override
public void restoreState(FacesContext context, Object state) {
if (context == null) {
throw new NullPointerException();
}
if (state == null) {
return;
}
methodExpressionOneArg = (MethodExpression) ((Object[]) state)[0];
methodExpressionZeroArg = (MethodExpression) ((Object[]) state)[1];
}
@Override
public boolean isTransient() {
return isTransient;
}
@Override
public void setTransient(boolean newTransientValue) {
isTransient = newTransientValue;
}
}