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 { private boolean isReadOnly; private static final int CACHE_SIZE = 1024; private static final ConcurrentHashMapBeanELResolver.
*/
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.
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.
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(true);
} 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.
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(true);
} 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 correcponding 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 = findMethod(base, method.toString(), paramTypes, params);
Object ret = invokeMethod(m, base, params);
context.setPropertyResolved(true);
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.
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:
*
PropertyDescriptor.getPropertyType().true.Iterator containing zero or more
* FeatureDescriptor objects, each representing a property
* on this bean, or null if the base
* object is null.
*/
public Iteratornull, 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.
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.putIfAbsent(baseClass, bps);
}
BeanProperty bp = bps.getBeanProperty(property);
if (bp == null) {
throw new PropertyNotFoundException(
ELUtil.getExceptionMessageString(context,
"propertyNotFound",
new Object[] { baseClass.getName(),
property}));
}
return bp;
}
private void removeFromMap(Map