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JSR-000344: JavaServer(TM) Faces 2.2 API
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package javax.faces.component;
import java.io.Serializable;
import javax.faces.component.StateHolder;
import javax.faces.context.FacesContext;
import javax.faces.el.EvaluationException;
import javax.faces.el.PropertyNotFoundException;
import javax.faces.el.ValueBinding;
import javax.el.ValueExpression;
import javax.el.ELException;
/**
* Wrap a ValueExpression instance and expose it as a ValueBinding
*
* @author Jacob Hookom
*/
class ValueBindingValueExpressionAdapter extends ValueBinding implements StateHolder,
Serializable {
private static final long serialVersionUID = -8015491904782686906L;
private ValueExpression valueExpression= null;
private boolean tranzient;
public ValueBindingValueExpressionAdapter() {} // for StateHolder
ValueBindingValueExpressionAdapter(ValueExpression valueExpression) {
this.valueExpression = valueExpression;
}
/* (non-Javadoc)
* @see javax.faces.el.ValueBinding#getExpressionString()
*/
public String getExpressionString() {
assert(null != valueExpression);
return valueExpression.getExpressionString();
}
/* (non-Javadoc)
* @see javax.faces.el.ValueBinding#getType(javax.faces.context.FacesContext)
*/
public Class getType(FacesContext context) throws EvaluationException,
PropertyNotFoundException {
if (context == null) {
throw new NullPointerException("FacesContext -> null");
}
Class result = null;
try {
result = valueExpression.getType(context.getELContext());
} catch (javax.el.PropertyNotFoundException pnfe) {
throw new PropertyNotFoundException(pnfe);
} catch (ELException elex) {
throw new EvaluationException(elex);
}
return result;
}
/* (non-Javadoc)
* @see javax.faces.el.ValueBinding#getValue(javax.faces.context.FacesContext)
*/
public Object getValue(FacesContext context) throws EvaluationException,
PropertyNotFoundException {
if (context == null) {
throw new NullPointerException("FacesContext -> null");
}
Object result = null;
try {
result = valueExpression.getValue(context.getELContext());
} catch (javax.el.PropertyNotFoundException pnfe) {
throw new PropertyNotFoundException(pnfe);
} catch (ELException elex) {
throw new EvaluationException(elex);
}
return result;
}
/* (non-Javadoc)
* @see javax.faces.el.ValueBinding#isReadOnly(javax.faces.context.FacesContext)
*/
public boolean isReadOnly(FacesContext context) throws EvaluationException,
PropertyNotFoundException {
if (context == null) {
throw new NullPointerException("FacesContext -> null");
}
boolean result = false;
try {
result = valueExpression.isReadOnly(context.getELContext());
} catch (ELException elex) {
throw new EvaluationException(elex);
}
return result;
}
/* (non-Javadoc)
* @see javax.faces.el.ValueBinding#setValue(javax.faces.context.FacesContext, java.lang.Object)
*/
public void setValue(FacesContext context, Object value)
throws EvaluationException, PropertyNotFoundException {
if (context == null) {
throw new NullPointerException("FacesContext -> null");
}
try {
valueExpression.setValue(context.getELContext(), value);
} catch (javax.el.PropertyNotFoundException pnfe) {
throw new PropertyNotFoundException(pnfe);
} catch (javax.el.PropertyNotWritableException pnwe) {
throw new PropertyNotFoundException(pnwe);
} catch (ELException elex) {
throw new EvaluationException(elex);
}
}
public boolean isTransient() {
return this.tranzient;
}
public void setTransient(boolean tranzient) {
this.tranzient = tranzient;
}
public Object saveState(FacesContext context){
if (context == null) {
throw new NullPointerException();
}
Object result = null;
if (!tranzient) {
if (valueExpression instanceof StateHolder) {
Object [] stateStruct = new Object[2];
// save the actual state of our wrapped valueExpression
stateStruct[0] = ((StateHolder)valueExpression).saveState(context);
// save the class name of the valueExpression impl
stateStruct[1] = valueExpression.getClass().getName();
result = stateStruct;
}
else {
result = valueExpression;
}
}
return result;
}
public void restoreState(FacesContext context, Object state) {
if (context == null) {
throw new NullPointerException();
}
// if we have state
if (null == state) {
return;
}
if (!(state instanceof ValueExpression)) {
Object [] stateStruct = (Object []) state;
Object savedState = stateStruct[0];
String className = stateStruct[1].toString();
ValueExpression result = null;
Class toRestoreClass = null;
if (null != className) {
try {
toRestoreClass = loadClass(className, this);
}
catch (ClassNotFoundException e) {
throw new IllegalStateException(e.getMessage());
}
if (null != toRestoreClass) {
try {
result =
(ValueExpression) toRestoreClass.newInstance();
}
catch (InstantiationException e) {
throw new IllegalStateException(e.getMessage());
}
catch (IllegalAccessException a) {
throw new IllegalStateException(a.getMessage());
}
}
if (null != result && null != savedState) {
// don't need to check transient, since that was
// done on the saving side.
((StateHolder)result).restoreState(context, savedState);
}
valueExpression = result;
}
}
else {
valueExpression = (ValueExpression) state;
}
}
public boolean equals(Object other) {
if (other == this) {
return true;
}
if (other instanceof ValueBindingValueExpressionAdapter) {
ValueExpression expr =
((ValueBindingValueExpressionAdapter) other).getWrapped();
return (valueExpression.equals(expr));
} else if (other instanceof ValueBinding) {
FacesContext context = FacesContext.getCurrentInstance();
ValueBinding otherVB = (ValueBinding) other;
Class type = otherVB.getType(context);
if (type != null) {
return type.equals(valueExpression.getType(context.getELContext()));
}
}
return false;
}
public int hashCode() {
assert(null != valueExpression);
return valueExpression.hashCode();
}
public ValueExpression getWrapped() {
return valueExpression;
}
//
// Helper methods for StateHolder
//
private static Class loadClass(String name,
Object fallbackClass) throws ClassNotFoundException {
ClassLoader loader =
Thread.currentThread().getContextClassLoader();
if (loader == null) {
loader = fallbackClass.getClass().getClassLoader();
}
return Class.forName(name, true, loader);
}
}