javax.el.BeanELResolver Maven / Gradle / Ivy
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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.
*
* 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 JSP 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 int CACHE_INIT_SIZE = 1024;
private ConcurrentHashMap, BPSoftReference> map =
new ConcurrentHashMap, BPSoftReference>(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 = 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 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 pd: descriptors) {
propertyMap.put(pd.getName(),
new BeanProperty(baseClass, pd));
}
}
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.
*/
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 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.
*/
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 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.
*/
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 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 method 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 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);
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 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.
*/
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 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.
*/
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 list = new ArrayList(
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 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.
*/
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;
}
}