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JSR-000344: JavaServer(TM) Faces 2.2 API
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package javax.faces.component;
import javax.el.ValueExpression;
import javax.el.ELException;
import javax.el.ELContext;
import javax.faces.el.ValueBinding;
import javax.faces.context.FacesContext;
import javax.faces.component.StateHolder;
import java.io.Serializable;
/**
* Wrap a ValueBinding instance and expose it as a
* ValueExpression.
*/
class ValueExpressionValueBindingAdapter extends ValueExpression implements Serializable, StateHolder {
private static final long serialVersionUID = 2388977392466671243L;
public ValueExpressionValueBindingAdapter() {}
private ValueBinding binding = null;
ValueExpressionValueBindingAdapter(ValueBinding binding) {
assert(null != binding);
this.binding = binding;
}
//
// Methods from ValueExpression
//
public Object getValue(ELContext context) throws ELException {
assert(null != binding);
if (context == null) {
throw new NullPointerException("ELContext -> null");
}
Object result = null;
FacesContext facesContext = (FacesContext)
context.getContext(FacesContext.class);
assert(null != facesContext);
try {
result = binding.getValue(facesContext);
}
catch (Throwable e) {
throw new ELException(e);
}
return result;
}
public void setValue(ELContext context, Object value) throws ELException {
assert(null != binding);
if (context == null) {
throw new NullPointerException("ELContext -> null");
}
FacesContext facesContext = (FacesContext)
context.getContext(FacesContext.class);
assert(null != facesContext);
try {
binding.setValue(facesContext, value);
}
catch (Throwable e) {
throw new ELException(e);
}
}
public boolean isReadOnly(ELContext context) throws ELException {
assert(null != binding);
if (context == null) {
throw new NullPointerException("ELContext -> null");
}
boolean result = false;
FacesContext facesContext = (FacesContext)
context.getContext(FacesContext.class);
assert(null != facesContext);
try {
result = binding.isReadOnly(facesContext);
}
catch (Throwable e) {
throw new ELException(e);
}
return result;
}
public Class getType(ELContext context) throws ELException {
assert(null != binding);
if (context == null) {
throw new NullPointerException("ELContext -> null");
}
Class result = null;
FacesContext facesContext = (FacesContext)
context.getContext(FacesContext.class);
assert(null != facesContext);
try {
result = binding.getType(facesContext);
}
catch (Throwable e) {
throw new ELException(e);
}
return result;
}
/**
* Always return false since we can't possibly know
* if this is a literal text binding or not.
*/
public boolean isLiteralText() {
return false;
}
public Class getExpectedType() {
assert(null != binding);
Class result = null;
FacesContext context = FacesContext.getCurrentInstance();
try {
Object value = binding.getValue(context);
result = value.getClass();
}
catch (Throwable e) {
result = null;
}
return result;
}
public String getExpressionString() {
assert(null != binding);
return binding.getExpressionString();
}
public boolean equals(Object other) {
if (other == this) {
return true;
}
if (other instanceof ValueExpressionValueBindingAdapter) {
ValueBinding vb =
((ValueExpressionValueBindingAdapter) other).getWrapped();
return (binding.equals(vb));
} else if (other instanceof ValueExpression) {
FacesContext context = FacesContext.getCurrentInstance();
ValueExpression otherVE = (ValueExpression) other;
Class type = binding.getType(context);
if (type != null) {
return type.equals(otherVE.getType(context.getELContext()));
}
}
return false;
}
public int hashCode() {
assert(null != binding);
return binding.hashCode();
}
public String getDelimiterSyntax() {
// PENDING (visvan) Implementation
return "";
}
//
// Methods from StateHolder
//
public Object saveState(FacesContext context) {
if (context == null) {
throw new NullPointerException();
}
Object result = null;
if (!tranzient) {
if (binding instanceof StateHolder) {
Object [] stateStruct = new Object[2];
// save the actual state of our wrapped binding
stateStruct[0] = ((StateHolder)binding).saveState(context);
// save the class name of the binding impl
stateStruct[1] = binding.getClass().getName();
result = stateStruct;
}
else {
result = binding;
}
}
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 ValueBinding)) {
Object [] stateStruct = (Object []) state;
Object savedState = stateStruct[0];
String className = stateStruct[1].toString();
ValueBinding 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 =
(ValueBinding) 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);
}
binding = result;
}
}
else {
binding = (ValueBinding) state;
}
}
private boolean tranzient = false;
public boolean isTransient() {
return tranzient;
}
public void setTransient(boolean newTransientValue) {
tranzient = newTransientValue;
}
//
// 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);
}
//
// methods used by classes aware of this class's wrapper nature
//
public ValueBinding getWrapped() {
return binding;
}
}