javax.el.BeanELResolver Maven / Gradle / Ivy
/*
* Copyright (c) 1997-2018 Oracle and/or its affiliates and others.
* All rights reserved.
* Copyright 2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package javax.el;
import static java.lang.Boolean.TRUE;
import static javax.el.ELUtil.getExceptionMessageString;
import java.beans.BeanInfo;
import java.beans.FeatureDescriptor;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.SoftReference;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/**
* Defines property resolution behavior on objects using the JavaBeans component architecture.
*
*
* This resolver handles base objects of any type, as long as the base is not null. It accepts any object
* as a property or method, and coerces it to a string.
*
*
* For property resolution, the property string is used to find a JavaBeans compliant property on the base object. The
* value is accessed using JavaBeans getters and setters.
*
*
*
* For method resolution, the method string is the name of the method in the bean. The parameter types can be optionally
* specified to identify the method. If the parameter types are not specified, the parameter objects are used in the
* method resolution.
*
*
*
* This resolver can be constructed in read-only mode, which means that {@link #isReadOnly} will always return
* true and {@link #setValue} will always throw PropertyNotWritableException.
*
*
*
* ELResolvers are combined together using {@link CompositeELResolver}s, to define rich semantics for
* evaluating an expression. See the javadocs for {@link ELResolver} for details.
*
*
*
* Because this resolver handles base objects of any type, it should be placed near the end of a composite resolver.
* Otherwise, it will claim to have resolved a property before any resolvers that come after it get a chance to test if
* they can do so as well.
*
*
* @see CompositeELResolver
* @see ELResolver
*
* @since Jakarta Server Pages 2.1
*/
public class BeanELResolver extends ELResolver {
static private class BPSoftReference extends SoftReference {
final Class key;
BPSoftReference(Class key, BeanProperties beanProperties, ReferenceQueue refQ) {
super(beanProperties, refQ);
this.key = key;
}
}
static private class SoftConcurrentHashMap extends ConcurrentHashMap, BeanProperties> {
private static final long serialVersionUID = -178867497897782229L;
private static final int CACHE_INIT_SIZE = 1024;
private ConcurrentHashMap, BPSoftReference> map = new ConcurrentHashMap<>(CACHE_INIT_SIZE);
private ReferenceQueue refQ = new ReferenceQueue<>();
// Remove map entries that have been placed on the queue by GC.
private void cleanup() {
BPSoftReference BPRef = null;
while ((BPRef = (BPSoftReference) refQ.poll()) != null) {
map.remove(BPRef.key);
}
}
@Override
public BeanProperties put(Class key, BeanProperties value) {
cleanup();
BPSoftReference prev = map.put(key, new BPSoftReference(key, value, refQ));
return prev == null ? null : prev.get();
}
@Override
public BeanProperties putIfAbsent(Class key, BeanProperties value) {
cleanup();
BPSoftReference prev = map.putIfAbsent(key, new BPSoftReference(key, value, refQ));
return prev == null ? null : prev.get();
}
@Override
public BeanProperties get(Object key) {
cleanup();
BPSoftReference BPRef = map.get(key);
if (BPRef == null) {
return null;
}
if (BPRef.get() == null) {
// value has been garbage collected, remove entry in map
map.remove(key);
return null;
}
return BPRef.get();
}
}
private boolean isReadOnly;
private static final SoftConcurrentHashMap properties = new SoftConcurrentHashMap();
/*
* Defines a property for a bean.
*/
final static class BeanProperty {
private Method readMethod;
private Method writeMethod;
private PropertyDescriptor descriptor;
public BeanProperty(Class baseClass, PropertyDescriptor descriptor) {
this.descriptor = descriptor;
readMethod = ELUtil.getMethod(baseClass, descriptor.getReadMethod());
writeMethod = ELUtil.getMethod(baseClass, descriptor.getWriteMethod());
}
public Class getPropertyType() {
return descriptor.getPropertyType();
}
public boolean isReadOnly() {
return getWriteMethod() == null;
}
public Method getReadMethod() {
return readMethod;
}
public Method getWriteMethod() {
return writeMethod;
}
}
/*
* Defines the properties for a bean.
*/
final static class BeanProperties {
private final Map propertyMap = new HashMap<>();
public BeanProperties(Class baseClass) {
PropertyDescriptor[] descriptors;
try {
BeanInfo info = Introspector.getBeanInfo(baseClass);
descriptors = info.getPropertyDescriptors();
} catch (IntrospectionException ie) {
throw new ELException(ie);
}
for (PropertyDescriptor descriptor : descriptors) {
propertyMap.put(descriptor.getName(), new BeanProperty(baseClass, descriptor));
}
}
public BeanProperty getBeanProperty(String property) {
return propertyMap.get(property);
}
}
/**
* Creates a new read/write BeanELResolver.
*/
public BeanELResolver() {
this.isReadOnly = false;
}
/**
* Creates a new BeanELResolver whose read-only status is determined by the given parameter.
*
* @param isReadOnly true if this resolver cannot modify beans; false otherwise.
*/
public BeanELResolver(boolean isReadOnly) {
this.isReadOnly = isReadOnly;
}
/**
* If the base object is not null, returns the most general acceptable type that can be set on this bean
* property.
*
*
* If the base is not null, the propertyResolved property of the ELContext object
* must be set to true by this resolver, before returning. If this property is not true after
* this method is called, the caller should ignore the return value.
*
*
*
* The provided property will first be coerced to a String. If there is a BeanInfoProperty for
* this property and there were no errors retrieving it, the propertyType of the
* propertyDescriptor is returned. Otherwise, a PropertyNotFoundException is thrown.
*
*
* @param context The context of this evaluation.
* @param base The bean to analyze.
* @param property The name of the property to analyze. Will be coerced to a String.
* @return If the propertyResolved property of ELContext was set to true, then
* the most general acceptable type; otherwise undefined.
* @throws NullPointerException if context is null
* @throws PropertyNotFoundException if base is not null and the specified property does not
* exist or is not readable.
* @throws ELException if an exception was thrown while performing the property or variable resolution. The thrown
* exception must be included as the cause property of this exception, if available.
*/
@Override
public Class getType(ELContext context, Object base, Object property) {
if (context == null) {
throw new NullPointerException();
}
if (base == null || property == null) {
return null;
}
BeanProperty beanProperty = getBeanProperty(context, base, property);
context.setPropertyResolved(true);
return beanProperty.getPropertyType();
}
/**
* If the base object is not null, returns the current value of the given property on this bean.
*
*
* If the base is not null, the propertyResolved property of the ELContext object
* must be set to true by this resolver, before returning. If this property is not true after
* this method is called, the caller should ignore the return value.
*
*
*
* The provided property name will first be coerced to a String. If the property is a readable property of
* the base object, as per the JavaBeans specification, then return the result of the getter call. If the getter throws
* an exception, it is propagated to the caller. If the property is not found or is not readable, a
* PropertyNotFoundException is thrown.
*
*
* @param context The context of this evaluation.
* @param base The bean on which to get the property.
* @param property The name of the property to get. Will be coerced to a String.
* @return If the propertyResolved property of ELContext was set to true, then
* the value of the given property. Otherwise, undefined.
* @throws NullPointerException if context is null.
* @throws PropertyNotFoundException if base is not null and the specified property does not
* exist or is not readable.
* @throws ELException if an exception was thrown while performing the property or variable resolution. The thrown
* exception must be included as the cause property of this exception, if available.
*/
@Override
public Object getValue(ELContext context, Object base, Object property) {
if (context == null) {
throw new NullPointerException();
}
if (base == null || property == null) {
return null;
}
Method method = getBeanProperty(context, base, property).getReadMethod();
if (method == null) {
throw new PropertyNotFoundException(
getExceptionMessageString(context, "propertyNotReadable", new Object[] { base.getClass().getName(), property.toString() }));
}
Object value;
try {
value = method.invoke(base, new Object[0]);
context.setPropertyResolved(base, property);
} catch (ELException ex) {
throw ex;
} catch (InvocationTargetException ite) {
throw new ELException(ite.getCause());
} catch (Exception ex) {
throw new ELException(ex);
}
return value;
}
/**
* If the base object is not null, attempts to set the value of the given property on this bean.
*
*
* If the base is not null, the propertyResolved property of the ELContext object
* must be set to true by this resolver, before returning. If this property is not true after
* this method is called, the caller can safely assume no value was set.
*
*
*
* If this resolver was constructed in read-only mode, this method will always throw
* PropertyNotWritableException.
*
*
*
* The provided property name will first be coerced to a String. If property is a writable property of
* base (as per the JavaBeans Specification), the setter method is called (passing value). If
* the property exists but does not have a setter, then a PropertyNotFoundException is thrown. If the
* property does not exist, a PropertyNotFoundException is thrown.
*
*
* @param context The context of this evaluation.
* @param base The bean on which to set the property.
* @param property The name of the property to set. Will be coerced to a String.
* @param val The value to be associated with the specified key.
* @throws NullPointerException if context is null.
* @throws PropertyNotFoundException if base is not null and the specified property does not
* exist.
* @throws PropertyNotWritableException if this resolver was constructed in read-only mode, or if there is no setter for
* the property.
* @throws ELException if an exception was thrown while performing the property or variable resolution. The thrown
* exception must be included as the cause property of this exception, if available.
*/
@Override
public void setValue(ELContext context, Object base, Object property, Object val) {
if (context == null) {
throw new NullPointerException();
}
if (base == null || property == null) {
return;
}
if (isReadOnly) {
throw new PropertyNotWritableException(getExceptionMessageString(context, "resolverNotwritable", new Object[] { base.getClass().getName() }));
}
Method method = getBeanProperty(context, base, property).getWriteMethod();
if (method == null) {
throw new PropertyNotWritableException(
getExceptionMessageString(context, "propertyNotWritable", new Object[] { base.getClass().getName(), property.toString() }));
}
try {
method.invoke(base, new Object[] { val });
context.setPropertyResolved(base, property);
} catch (ELException ex) {
throw ex;
} catch (InvocationTargetException ite) {
throw new ELException(ite.getCause());
} catch (Exception ex) {
if (null == val) {
val = "null";
}
String message = getExceptionMessageString(context, "setPropertyFailed", new Object[] { property.toString(), base.getClass().getName(), val });
throw new ELException(message, ex);
}
}
/**
* If the base object is not null, invoke the method, with the given parameters on this bean. The return
* value from the method is returned.
*
*
* If the base is not null, the propertyResolved property of the ELContext object
* must be set to true by this resolver, before returning. If this property is not true after
* this method is called, the caller should ignore the return value.
*
*
*
* The provided method object will first be coerced to a String. The methods in the bean is then examined
* and an attempt will be made to select one for invocation. If no suitable can be found, a
* MethodNotFoundException is thrown.
*
* If the given paramTypes is not null, select the method with the given name and parameter types.
*
* Else select the method with the given name that has the same number of parameters. If there are more than one such
* method, the method selection process is undefined.
*
* Else select the method with the given name that takes a variable number of arguments.
*
* Note the resolution for overloaded methods will likely be clarified in a future version of the spec.
*
* The provide parameters are coerced to the corresponding parameter types of the method, and the method is then
* invoked.
*
* @param context The context of this evaluation.
* @param base The bean on which to invoke the method
* @param methodName The simple name of the method to invoke. Will be coerced to a String. If method is
* "<init>"or "<clinit>" a MethodNotFoundException is thrown.
* @param paramTypes An array of Class objects identifying the method's formal parameter types, in declared order. Use
* an empty array if the method has no parameters. Can be null, in which case the method's formal parameter
* types are assumed to be unknown.
* @param params The parameters to pass to the method, or null if no parameters.
* @return The result of the method invocation (null if the method has a void return type).
* @throws MethodNotFoundException if no suitable method can be found.
* @throws ELException if an exception was thrown while performing (base, method) resolution. The thrown exception must
* be included as the cause property of this exception, if available. If the exception thrown is an
* InvocationTargetException, extract its cause and pass it to the ELException
* constructor.
* @since Jakarta Expression Language 2.2
*/
@Override
public Object invoke(ELContext context, Object base, Object methodName, Class[] paramTypes, Object[] params) {
if (base == null || methodName == null) {
return null;
}
Method method = ELUtil.findMethod(base.getClass(), methodName.toString(), paramTypes, params, false);
for (Object param : params) {
// If the parameters is a LambdaExpression, set the ELContext
// for its evaluation
if (param instanceof LambdaExpression) {
((LambdaExpression) param).setELContext(context);
}
}
Object ret = ELUtil.invokeMethod(context, method, base, params);
context.setPropertyResolved(base, methodName);
return ret;
}
/**
* If the base object is not null, returns whether a call to {@link #setValue} will always fail.
*
*
* If the base is not null, the propertyResolved property of the ELContext object
* must be set to true by this resolver, before returning. If this property is not true after
* this method is called, the caller can safely assume no value was set.
*
*
*
* If this resolver was constructed in read-only mode, this method will always return true.
*
*
*
* The provided property name will first be coerced to a String. If property is a writable property of
* base, false is returned. If the property is found but is not writable, true is
* returned. If the property is not found, a PropertyNotFoundException is thrown.
*
*
* @param context The context of this evaluation.
* @param base The bean to analyze.
* @param property The name of the property to analyzed. Will be coerced to a String.
* @return If the propertyResolved property of ELContext was set to true, then
* true if calling the setValue method will always fail or false if it is
* possible that such a call may succeed; otherwise undefined.
* @throws NullPointerException if context is null
* @throws PropertyNotFoundException if base is not null and the specified property does not
* exist.
* @throws ELException if an exception was thrown while performing the property or variable resolution. The thrown
* exception must be included as the cause property of this exception, if available.
*/
@Override
public boolean isReadOnly(ELContext context, Object base, Object property) {
if (context == null) {
throw new NullPointerException();
}
if (base == null || property == null) {
return false;
}
context.setPropertyResolved(true);
if (isReadOnly) {
return true;
}
return getBeanProperty(context, base, property).isReadOnly();
}
/**
* If the base object is not null, returns an Iterator containing the set of JavaBeans
* properties available on the given object. Otherwise, returns null.
*
*
* The Iterator returned must contain zero or more instances of {@link java.beans.FeatureDescriptor}. Each
* info object contains information about a property in the bean, as obtained by calling the
* BeanInfo.getPropertyDescriptors method. The FeatureDescriptor is initialized using the same
* fields as are present in the PropertyDescriptor, with the additional required named attributes
* "type" and "resolvableAtDesignTime" set as follows:
*
* - {@link ELResolver#TYPE} - The runtime type of the property, from
*
PropertyDescriptor.getPropertyType().
* - {@link ELResolver#RESOLVABLE_AT_DESIGN_TIME} -
true.
*
*
*
* @param context The context of this evaluation.
* @param base The bean to analyze.
* @return An Iterator containing zero or more FeatureDescriptor objects, each representing a
* property on this bean, or null if the base object is null.
*/
@Override
public Iterator getFeatureDescriptors(ELContext context, Object base) {
if (base == null) {
return null;
}
BeanInfo info = null;
try {
info = Introspector.getBeanInfo(base.getClass());
} catch (Exception ex) {
}
if (info == null) {
return null;
}
ArrayList featureDescriptors = new ArrayList<>(info.getPropertyDescriptors().length);
for (PropertyDescriptor propertyDescriptor : info.getPropertyDescriptors()) {
propertyDescriptor.setValue("type", propertyDescriptor.getPropertyType());
propertyDescriptor.setValue("resolvableAtDesignTime", TRUE);
featureDescriptors.add(propertyDescriptor);
}
return featureDescriptors.iterator();
}
/**
* If the base object is not null, returns the most general type that this resolver accepts for the
* property argument. Otherwise, returns null.
*
*
* Assuming the base is not null, this method will always return Object.class. This is because
* any object is accepted as a key and is coerced into a string.
*
*
* @param context The context of this evaluation.
* @param base The bean to analyze.
* @return null if base is null; otherwise Object.class.
*/
@Override
public Class getCommonPropertyType(ELContext context, Object base) {
if (base == null) {
return null;
}
return Object.class;
}
private BeanProperty getBeanProperty(ELContext context, Object base, Object prop) {
String property = prop.toString();
Class baseClass = base.getClass();
BeanProperties beanProperties = properties.get(baseClass);
if (beanProperties == null) {
beanProperties = new BeanProperties(baseClass);
properties.put(baseClass, beanProperties);
}
BeanProperty beanProperty = beanProperties.getBeanProperty(property);
if (beanProperty == null) {
throw new PropertyNotFoundException(getExceptionMessageString(context, "propertyNotFound", new Object[] { baseClass.getName(), property }));
}
return beanProperty;
}
}