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* Copyright 2004 The Apache Software Foundation
*
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*
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package javax.el;
import java.lang.reflect.
InvocationTargetException;
import java.lang.reflect.
Method;
import java.lang.reflect.
Modifier;
import java.lang.ref.
SoftReference;
import java.lang.ref.
ReferenceQueue;
import java.beans.
FeatureDescriptor;
import java.beans.
BeanInfo;
import java.beans.
Introspector;
import java.beans.
PropertyDescriptor;
import java.beans.
IntrospectionException;
import java.util.
Iterator;
import java.util.
ArrayList;
import java.util.
Map;
import java.util.
HashMap;
import java.util.concurrent.
ConcurrentHashMap;
/**
* Defines property resolution behavior on objects using the JavaBeans
* component architecture.
*
* <p>This resolver handles base objects of any type, as long as the
* base is not <code>null</code>. It accepts any object as a property
* or method, and coerces it to a string.
*
* <p>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.
* </p>
*
* <p>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.
* </p>
*
* <p>This resolver can be constructed in read-only mode, which means that
* {@link #isReadOnly} will always return <code>true</code> and
* {@link #setValue} will always throw
* <code>PropertyNotWritableException</code>.</p>
*
* <p><code>ELResolver</code>s are combined together using
* {@link CompositeELResolver}s, to define rich semantics for evaluating
* an expression. See the javadocs for {@link ELResolver} for details.</p>
*
* <p>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.</p>
*
* @see CompositeELResolver
* @see ELResolver
* @since JSP 2.1
*/
public class
BeanELResolver extends
ELResolver {
static private class
BPSoftReference extends
SoftReference<
BeanProperties> {
final
Class<?>
key;
BPSoftReference(
Class<?>
key,
BeanProperties beanProperties,
ReferenceQueue<
BeanProperties>
refQ) {
super(
beanProperties,
refQ);
this.
key =
key;
}
}
static private class
SoftConcurrentHashMap extends
ConcurrentHashMap<
Class<?>,
BeanProperties> {
private static final int
CACHE_INIT_SIZE = 1024;
private
ConcurrentHashMap<
Class<?>,
BPSoftReference>
map =
new
ConcurrentHashMap<
Class<?>,
BPSoftReference>(
CACHE_INIT_SIZE);
private
ReferenceQueue<
BeanProperties>
refQ =
new
ReferenceQueue<
BeanProperties>();
// 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 =
getMethod(
baseClass,
descriptor.
getReadMethod());
writeMethod =
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<
String,
BeanProperty>
propertyMap =
new
HashMap<
String,
BeanProperty>();
public
BeanProperties(
Class<?>
baseClass) {
PropertyDescriptor[]
descriptors;
try {
BeanInfo info =
Introspector.
getBeanInfo(
baseClass);
descriptors =
info.
getPropertyDescriptors();
} catch (
IntrospectionException ie) {
throw new
ELException(
ie);
}
for (
PropertyDescriptor pd:
descriptors) {
propertyMap.
put(
pd.
getName(),
new
BeanProperty(
baseClass,
pd));
}
}
public
BeanProperty getBeanProperty(
String property) {
return
propertyMap.
get(
property);
}
}
/**
* Creates a new read/write <code>BeanELResolver</code>.
*/
public
BeanELResolver() {
this.
isReadOnly = false;
}
/**
* Creates a new <code>BeanELResolver</code> whose read-only status is
* determined by the given parameter.
*
* @param isReadOnly <code>true</code> if this resolver cannot modify
* beans; <code>false</code> otherwise.
*/
public
BeanELResolver(boolean
isReadOnly) {
this.
isReadOnly =
isReadOnly;
}
/**
* If the base object is not <code>null</code>, returns the most
* general acceptable type that can be set on this bean property.
*
* <p>If the base is not <code>null</code>, the
* <code>propertyResolved</code> property of the <code>ELContext</code>
* object must be set to <code>true</code> by this resolver, before
* returning. If this property is not <code>true</code> after this
* method is called, the caller should ignore the return value.</p>
*
* <p>The provided property will first be coerced to a <code>String</code>.
* If there is a <code>BeanInfoProperty</code> for this property and
* there were no errors retrieving it, the <code>propertyType</code> of
* the <code>propertyDescriptor</code> is returned. Otherwise, a
* <code>PropertyNotFoundException</code> is thrown.</p>
*
* @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 <code>String</code>.
* @return If the <code>propertyResolved</code> property of
* <code>ELContext</code> was set to <code>true</code>, then
* the most general acceptable type; otherwise undefined.
* @throws NullPointerException if context is <code>null</code>
* @throws PropertyNotFoundException if <code>base</code> is not
* <code>null</code> 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.
*/
public
Class<?>
getType(
ELContext context,
Object base,
Object property) {
if (
context == null) {
throw new
NullPointerException();
}
if (
base == null ||
property == null){
return null;
}
BeanProperty bp =
getBeanProperty(
context,
base,
property);
context.
setPropertyResolved(true);
return
bp.
getPropertyType();
}
/**
* If the base object is not <code>null</code>, returns the current
* value of the given property on this bean.
*
* <p>If the base is not <code>null</code>, the
* <code>propertyResolved</code> property of the <code>ELContext</code>
* object must be set to <code>true</code> by this resolver, before
* returning. If this property is not <code>true</code> after this
* method is called, the caller should ignore the return value.</p>
*
* <p>The provided property name will first be coerced to a
* <code>String</code>. 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 <code>PropertyNotFoundException</code> is thrown.</p>
*
* @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 <code>String</code>.
* @return If the <code>propertyResolved</code> property of
* <code>ELContext</code> was set to <code>true</code>, then
* the value of the given property. Otherwise, undefined.
* @throws NullPointerException if context is <code>null</code>.
* @throws PropertyNotFoundException if <code>base</code> is not
* <code>null</code> 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.
*/
public
Object getValue(
ELContext context,
Object base,
Object property) {
if (
context == null) {
throw new
NullPointerException();
}
if (
base == null ||
property == null){
return null;
}
BeanProperty bp =
getBeanProperty(
context,
base,
property);
Method method =
bp.
getReadMethod();
if (
method == null) {
throw new
PropertyNotFoundException(
ELUtil.
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 <code>null</code>, attempts to set the
* value of the given property on this bean.
*
* <p>If the base is not <code>null</code>, the
* <code>propertyResolved</code> property of the <code>ELContext</code>
* object must be set to <code>true</code> by this resolver, before
* returning. If this property is not <code>true</code> after this
* method is called, the caller can safely assume no value was set.</p>
*
* <p>If this resolver was constructed in read-only mode, this method will
* always throw <code>PropertyNotWritableException</code>.</p>
*
* <p>The provided property name will first be coerced to a
* <code>String</code>. If property is a writable property of
* <code>base</code> (as per the JavaBeans Specification), the setter
* method is called (passing <code>value</code>). If the property exists
* but does not have a setter, then a
* <code>PropertyNotFoundException</code> is thrown. If the property
* does not exist, a <code>PropertyNotFoundException</code> is thrown.</p>
*
* @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 <code>String</code>.
* @param val The value to be associated with the specified key.
* @throws NullPointerException if context is <code>null</code>.
* @throws PropertyNotFoundException if <code>base</code> is not
* <code>null</code> 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.
*/
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(
ELUtil.
getExceptionMessageString(
context,
"resolverNotwritable",
new
Object[] {
base.
getClass().
getName() }));
}
BeanProperty bp =
getBeanProperty(
context,
base,
property);
Method method =
bp.
getWriteMethod();
if (
method == null) {
throw new
PropertyNotWritableException(
ELUtil.
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 =
ELUtil.
getExceptionMessageString(
context,
"setPropertyFailed",
new
Object[] {
property.
toString(),
base.
getClass().
getName(),
val });
throw new
ELException(
message,
ex);
}
}
/**
* If the base object is not <code>null</code>, invoke the method, with
* the given parameters on this bean. The return value from the method
* is returned.
*
* <p>If the base is not <code>null</code>, the
* <code>propertyResolved</code> property of the <code>ELContext</code>
* object must be set to <code>true</code> by this resolver, before
* returning. If this property is not <code>true</code> after this
* method is called, the caller should ignore the return value.</p>
*
* <p>The provided method object will first be coerced to a
* <code>String</code>. 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 <code>MethodNotFoundException</code> is thrown.
*
* If the given paramTypes is not <code>null</code>, 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 method The simple name of the method to invoke.
* Will be coerced to a <code>String</code>. 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 <code>null</code>, in which case the method's formal
* parameter types are assumed to be unknown.
* @param params The parameters to pass to the method, or
* <code>null</code> if no parameters.
* @return The result of the method invocation (<code>null</code> if
* the method has a <code>void</code> 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
* <code>InvocationTargetException</code>, extract its
* <code>cause</code> and pass it to the
* <code>ELException</code> constructor.
* @since EL 2.2
*/
public
Object invoke(
ELContext context,
Object base,
Object method,
Class<?>[]
paramTypes,
Object[]
params) {
if (
base == null ||
method == null) {
return null;
}
Method m =
ELUtil.
findMethod(
base.
getClass(),
method.
toString(),
paramTypes,
params, false);
m =
getMethod(
base.
getClass(),
m);
for (
Object p:
params) {
// If the parameters is a LambdaExpression, set the ELContext
// for its evaluation
if (
p instanceof javax.el.
LambdaExpression) {
((javax.el.
LambdaExpression)
p).
setELContext(
context);
}
}
Object ret =
ELUtil.
invokeMethod(
context,
m,
base,
params);
context.
setPropertyResolved(
base,
method);
return
ret;
}
/**
* If the base object is not <code>null</code>, returns whether a call
* to {@link #setValue} will always fail.
*
* <p>If the base is not <code>null</code>, the
* <code>propertyResolved</code> property of the <code>ELContext</code>
* object must be set to <code>true</code> by this resolver, before
* returning. If this property is not <code>true</code> after this
* method is called, the caller can safely assume no value was set.</p>
*
* <p>If this resolver was constructed in read-only mode, this method will
* always return <code>true</code>.</p>
*
* <p>The provided property name will first be coerced to a
* <code>String</code>. If property is a writable property of
* <code>base</code>, <code>false</code> is returned. If the property is
* found but is not writable, <code>true</code> is returned. If the
* property is not found, a <code>PropertyNotFoundException</code>
* is thrown.</p>
*
* @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 <code>String</code>.
* @return If the <code>propertyResolved</code> property of
* <code>ELContext</code> was set to <code>true</code>, then
* <code>true</code> if calling the <code>setValue</code> method
* will always fail or <code>false</code> if it is possible that
* such a call may succeed; otherwise undefined.
* @throws NullPointerException if context is <code>null</code>
* @throws PropertyNotFoundException if <code>base</code> is not
* <code>null</code> 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.
*/
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;
}
BeanProperty bp =
getBeanProperty(
context,
base,
property);
return
bp.
isReadOnly();
}
/**
* If the base object is not <code>null</code>, returns an
* <code>Iterator</code> containing the set of JavaBeans properties
* available on the given object. Otherwise, returns <code>null</code>.
*
* <p>The <code>Iterator</code> 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 <code>BeanInfo.getPropertyDescriptors</code> method.
* The <code>FeatureDescriptor</code> is initialized using the same
* fields as are present in the <code>PropertyDescriptor</code>,
* with the additional required named attributes "<code>type</code>" and
* "<code>resolvableAtDesignTime</code>" set as follows:
* <dl>
* <li>{@link ELResolver#TYPE} - The runtime type of the property, from
* <code>PropertyDescriptor.getPropertyType()</code>.</li>
* <li>{@link ELResolver#RESOLVABLE_AT_DESIGN_TIME} - <code>true</code>.</li>
* </dl>
* </p>
*
* @param context The context of this evaluation.
* @param base The bean to analyze.
* @return An <code>Iterator</code> containing zero or more
* <code>FeatureDescriptor</code> objects, each representing a property
* on this bean, or <code>null</code> if the <code>base</code>
* object is <code>null</code>.
*/
public
Iterator<
FeatureDescriptor>
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<
FeatureDescriptor>
list = new
ArrayList<
FeatureDescriptor>(
info.
getPropertyDescriptors().length);
for (
PropertyDescriptor pd:
info.
getPropertyDescriptors()) {
pd.
setValue("type",
pd.
getPropertyType());
pd.
setValue("resolvableAtDesignTime",
Boolean.
TRUE);
list.
add(
pd);
}
return
list.
iterator();
}
/**
* If the base object is not <code>null</code>, returns the most
* general type that this resolver accepts for the
* <code>property</code> argument. Otherwise, returns <code>null</code>.
*
* <p>Assuming the base is not <code>null</code>, this method will always
* return <code>Object.class</code>. This is because any object is
* accepted as a key and is coerced into a string.</p>
*
* @param context The context of this evaluation.
* @param base The bean to analyze.
* @return <code>null</code> if base is <code>null</code>; otherwise
* <code>Object.class</code>.
*/
public
Class<?>
getCommonPropertyType(
ELContext context,
Object base) {
if (
base == null){
return null;
}
return
Object.class;
}
/*
* Get a public method form a public class or interface of a given method.
* Note that if a PropertyDescriptor is obtained for a non-public class that
* implements a public interface, the read/write methods will be for the
* class, and therefore inaccessible. To correct this, a version of the
* same method must be found in a superclass or interface.
**/
static private
Method getMethod(
Class<?>
cl,
Method method) {
if (
method == null) {
return null;
}
if (
Modifier.
isPublic (
cl.
getModifiers ())) {
return
method;
}
Class<?> []
interfaces =
cl.
getInterfaces ();
for (int
i = 0;
i <
interfaces.length;
i++) {
Class<?>
c =
interfaces[
i];
Method m = null;
try {
m =
c.
getMethod(
method.
getName(),
method.
getParameterTypes());
c =
m.
getDeclaringClass();
if ((
m =
getMethod(
c,
m)) != null)
return
m;
} catch (
NoSuchMethodException ex) {
}
}
Class<?>
c =
cl.
getSuperclass();
if (
c != null) {
Method m = null;
try {
m =
c.
getMethod(
method.
getName(),
method.
getParameterTypes());
c =
m.
getDeclaringClass();
if ((
m =
getMethod(
c,
m)) != null)
return
m;
} catch (
NoSuchMethodException ex) {
}
}
return null;
}
private
BeanProperty getBeanProperty(
ELContext context,
Object base,
Object prop) {
String property =
prop.
toString();
Class baseClass =
base.
getClass();
BeanProperties bps =
properties.
get(
baseClass);
if (
bps == null) {
bps = new
BeanProperties(
baseClass);
properties.
put(
baseClass,
bps);
}
BeanProperty bp =
bps.
getBeanProperty(
property);
if (
bp == null) {
throw new
PropertyNotFoundException(
ELUtil.
getExceptionMessageString(
context,
"propertyNotFound",
new
Object[] {
baseClass.
getName(),
property}));
}
return
bp;
}
}