jakarta.el.RecordELResolver Maven / Gradle / Ivy
/*
* Copyright (c) 2024 Contributors to the Eclipse Foundation
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package jakarta.el;
import static jakarta.el.ELUtil.getExceptionMessageString;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Objects;
/**
* Defines property resolution behavior on instances of {@link Record}.
*
* The resolver handles base objects of type {@link Record}. It accepts any non-{@code null} object as a property and
* coerces it to a String using {@link Object#toString()}. The property string is used to find an accessor method for a
* field with the same name.
*
* This resolver is always read-only since {@link Record}s are always read-only.
*
* {@code ELResolver}s are combined together using {@link CompositeELResolver}s to define rich semantics for evaluating
* an expression. See the javadocs for {@link ELResolver} for details.
*/
public class RecordELResolver extends ELResolver {
/**
* If the base object is an instance of {@link Record}, returns the value of the given field of this {@link Record}.
*
* If the base object is an instance of {@link Record}, the {@code propertyResolved} property of the provided
* {@link ELContext} must be set to {@code true} by this resolver before returning. If this property is not {@code
* true} after this method is called, the caller should ignore the return value.
*
* @param context The context of this evaluation.
* @param base The {@link Record} on which to get the property.
* @param property The property to get. Will be coerced to a String.
*
* @return If the {@code propertyResolved} property of the provided {@link ELContext} was set to {@code true} then
* the value of the given property. Otherwise, undefined.
*
* @throws NullPointerException if the provided {@link ELContext} is {@code null}.
* @throws PropertyNotFoundException if the {@code base} is an instance of {@link Record} and the specified property
* does not exist.
* @throws ELException if an exception was thrown while performing the property resolution. The thrown
* exception must be included as the cause of this exception, if available.
*/
@Override
public Object getValue(ELContext context, Object base, Object property) {
Objects.requireNonNull(context);
if (base instanceof Record && property != null) {
context.setPropertyResolved(base, property);
String propertyName = property.toString();
Method method;
try {
method = base.getClass().getMethod(propertyName);
} catch (NoSuchMethodException nsme) {
throw new PropertyNotFoundException(
getExceptionMessageString(context, "propertyNotReadable", new Object[] { base.getClass().getName(), property.toString() }));
}
try {
return method.invoke(base);
} catch (ELException ex) {
throw ex;
} catch (InvocationTargetException ite) {
throw new ELException(ite.getCause());
} catch (Exception ex) {
throw new ELException(ex);
}
}
return null;
}
/**
* If the base object is an instance of {@link Record}, always returns {@code null} since {@link Record}s are always
* read-only.
*
* If the base object is an instance of {@link Record}, the {@code propertyResolved} property of the provided
* {@link ELContext} must be set to {@code true} by this resolver before returning. If this property is not {@code
* true} after this method is called, the caller should ignore the return value.
*
* @param context The context of this evaluation.
* @param base The {@link Record} to analyze.
* @param property The name of the property to analyze. Will be coerced to a String.
*
* @return Always {@code null}
*
* @throws NullPointerException if the provided {@link ELContext} is {@code null}.
* @throws PropertyNotFoundException if the {@code base} is an instance of {@link Record} and the specified property
* does not exist.
*/
@Override
public Class getType(ELContext context, Object base, Object property) {
Objects.requireNonNull(context);
if (base instanceof Record && property != null) {
context.setPropertyResolved(base, property);
String propertyName = property.toString();
try {
base.getClass().getMethod(propertyName);
} catch (NoSuchMethodException nsme) {
throw new PropertyNotFoundException(
getExceptionMessageString(context, "propertyNotReadable", new Object[] { base.getClass().getName(), property.toString() }));
}
}
return null;
}
/**
* If the base object is an instance of {@link Record}, always throws an exception since {@link Record}s are
* read-only.
*
* If the base object is an instance of {@link Record}, the {@code propertyResolved} property of the provided
* {@link ELContext} must be set to {@code true} by this resolver before returning. If this property is not {@code
* true} after this method is called, the caller should ignore the return value.
*
* @param context The context of this evaluation.
* @param base The {@link Record} on which to set the property.
* @param property The name of the property to set. Will be coerced to a String.
*
* @throws NullPointerException if the provided {@link ELContext} is {@code null}.
* @throws PropertyNotFoundException if the {@code base} is an instance of {@link Record} and the specified
* property does not exist.
* @throws PropertyNotWritableException if the {@code base} is an instance of {@link Record} and the specified
* property exists.
*/
@Override
public void setValue(ELContext context, Object base, Object property, Object value) {
Objects.requireNonNull(context);
if (base instanceof Record && property != null) {
context.setPropertyResolved(base, property);
String propertyName = property.toString();
try {
base.getClass().getMethod(propertyName);
} catch (NoSuchMethodException nsme) {
throw new PropertyNotFoundException(
getExceptionMessageString(context, "propertyNotFound", new Object[] { base.getClass().getName(), property.toString() }));
}
throw new PropertyNotWritableException(
getExceptionMessageString(context, "propertyNotWritable", new Object[] { base.getClass().getName(), property.toString() }));
}
}
/**
* If the base object is an instance of {@link Record}, always returns {@code true}.
*
* If the base object is an instance of {@link Record}, the {@code propertyResolved} property of the provided
* {@link ELContext} must be set to {@code true} by this resolver before returning. If this property is not {@code
* true} after this method is called, the caller should ignore the return value.
*
* @param context The context of this evaluation.
* @param base The {@link Record} to analyze.
* @param property The name of the property to analyze. Will be coerced to a String.
*
* @throws NullPointerException if the provided {@link ELContext} is {@code null}.
* @throws PropertyNotFoundException if the {@code base} is an instance of {@link Record} and the specified property
* does not exist.
*/
@Override
public boolean isReadOnly(ELContext context, Object base, Object property) {
Objects.requireNonNull(context);
if (base instanceof Record && property != null) {
context.setPropertyResolved(base, property);
String propertyName = property.toString();
try {
base.getClass().getMethod(propertyName);
} catch (NoSuchMethodException nsme) {
throw new PropertyNotFoundException(
getExceptionMessageString(context, "propertyNotFound", new Object[] { base.getClass().getName(), property.toString() }));
}
return true;
}
return false;
}
/**
* If the base object is an instance of {@link Record}, returns the most general type this resolver accepts for the
* {@code property} argument. Otherwise, returns {@code null}.
*
* If the base object is an instance of {@link Record} this method will always return {@link Object} since any
* object is accepted for the property argument and coerced to a String.
*
* @param context The context of this evaluation.
* @param base The {@link Record} to analyze.
*
* @return {@link Object} is base is an instance of {@link Record}, otherwise {@code null}.
*/
@Override
public Class getCommonPropertyType(ELContext context, Object base) {
if (base instanceof Record) {
// Fields can be of any type
return Object.class;
}
return null;
}
}