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Google App Engine compliant variation of FreeMarker.
FreeMarker is a "template engine"; a generic tool to generate text output based on templates.
/*
* Copyright 2014 Attila Szegedi, Daniel Dekany, Jonathan Revusky
*
* 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 freemarker.ext.beans;
import java.beans.IndexedPropertyDescriptor;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import freemarker.core.CollectionAndSequence;
import freemarker.core._DelayedFTLTypeDescription;
import freemarker.core._DelayedJQuote;
import freemarker.core._TemplateModelException;
import freemarker.ext.util.ModelFactory;
import freemarker.ext.util.WrapperTemplateModel;
import freemarker.log.Logger;
import freemarker.template.AdapterTemplateModel;
import freemarker.template.ObjectWrapper;
import freemarker.template.SimpleScalar;
import freemarker.template.SimpleSequence;
import freemarker.template.TemplateCollectionModel;
import freemarker.template.TemplateHashModelEx;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;
import freemarker.template.TemplateModelIterator;
import freemarker.template.TemplateScalarModel;
import freemarker.template.utility.StringUtil;
/**
* A class that will wrap an arbitrary object into {@link freemarker.template.TemplateHashModel}
* interface allowing calls to arbitrary property getters and invocation of
* accessible methods on the object from a template using the
* object.foo to access properties and object.bar(arg1, arg2) to
* invoke methods on it. You can also use the object.foo[index] syntax to
* access indexed properties. It uses Beans {@link java.beans.Introspector}
* to dynamically discover the properties and methods.
*/
public class BeanModel
implements
TemplateHashModelEx, AdapterTemplateModel, WrapperTemplateModel
{
private static final Logger logger = Logger.getLogger("freemarker.beans");
protected final Object object;
protected final BeansWrapper wrapper;
// We use this to represent an unknown value as opposed to known value of null (JR)
static final TemplateModel UNKNOWN = new SimpleScalar("UNKNOWN");
static final ModelFactory FACTORY =
new ModelFactory()
{
public TemplateModel create(Object object, ObjectWrapper wrapper)
{
return new BeanModel(object, (BeansWrapper)wrapper);
}
};
// Cached template models that implement member properties and methods for this
// instance. Keys are FeatureDescriptor instances (from classCache values),
// values are either ReflectionMethodModels/ReflectionScalarModels
private HashMap memberMap;
/**
* Creates a new model that wraps the specified object. Note that there are
* specialized subclasses of this class for wrapping arrays, collections,
* enumeration, iterators, and maps. Note also that the superclass can be
* used to wrap String objects if only scalar functionality is needed. You
* can also choose to delegate the choice over which model class is used for
* wrapping to {@link BeansWrapper#wrap(Object)}.
* @param object the object to wrap into a model.
* @param wrapper the {@link BeansWrapper} associated with this model.
* Every model has to have an associated {@link BeansWrapper} instance. The
* model gains many attributes from its wrapper, including the caching
* behavior, method exposure level, method-over-item shadowing policy etc.
*/
public BeanModel(Object object, BeansWrapper wrapper)
{
// TODO 2.4: All models were introspected here, then the results was discareded, and get() will just do the
// introspection again. So is this necessary? (The inrospectNow parameter was added in 2.3.21 to allow
// lazy-introspecting BeansWrapper.trueModel|falseModel.)
this(object, wrapper, true);
}
/** @since 2.3.21 */
BeanModel(Object object, BeansWrapper wrapper, boolean inrospectNow)
{
this.object = object;
this.wrapper = wrapper;
if (inrospectNow && object != null) {
// TODO: Could this be removed? [FM 2.4]
wrapper.getClassIntrospector().get(object.getClass());
}
}
/**
* Uses Beans introspection to locate a property or method with name
* matching the key name. If a method or property is found, it's wrapped
* into {@link freemarker.template.TemplateMethodModelEx} (for a method or
* indexed property), or evaluated on-the-fly and the return value wrapped
* into appropriate model (for a simple property) Models for various
* properties and methods are cached on a per-class basis, so the costly
* introspection is performed only once per property or method of a class.
* (Side-note: this also implies that any class whose method has been called
* will be strongly referred to by the framework and will not become
* unloadable until this class has been unloaded first. Normally this is not
* an issue, but can be in a rare scenario where you create many classes on-
* the-fly. Also, as the cache grows with new classes and methods introduced
* to the framework, it may appear as if it were leaking memory. The
* framework does, however detect class reloads (if you happen to be in an
* environment that does this kind of things--servlet containers do it when
* they reload a web application) and flushes the cache. If no method or
* property matching the key is found, the framework will try to invoke
* methods with signature
* non-void-return-type get(java.lang.String),
* then non-void-return-type get(java.lang.Object), or
* alternatively (if the wrapped object is a resource bundle)
* Object getObject(java.lang.String).
* @throws TemplateModelException if there was no property nor method nor
* a generic get method to invoke.
*/
public TemplateModel get(String key)
throws
TemplateModelException
{
Class clazz = object.getClass();
Map classInfo = wrapper.getClassIntrospector().get(clazz);
TemplateModel retval = null;
try
{
if(wrapper.isMethodsShadowItems())
{
Object fd = classInfo.get(key);
if(fd != null)
{
retval = invokeThroughDescriptor(fd, classInfo);
} else {
retval = invokeGenericGet(classInfo, clazz, key);
}
}
else
{
TemplateModel model = invokeGenericGet(classInfo, clazz, key);
final TemplateModel nullModel = wrapper.wrap(null);
if(model != nullModel && model != UNKNOWN)
{
return model;
}
Object fd = classInfo.get(key);
if(fd != null) {
retval = invokeThroughDescriptor(fd, classInfo);
if (retval == UNKNOWN && model == nullModel) {
// This is the (somewhat subtle) case where the generic get() returns null
// and we have no bean info, so we respect the fact that
// the generic get() returns null and return null. (JR)
retval = nullModel;
}
}
}
if (retval == UNKNOWN) {
if (wrapper.isStrict()) {
throw new InvalidPropertyException("No such bean property: " + key);
} else if (logger.isDebugEnabled()) {
logNoSuchKey(key, classInfo);
}
retval = wrapper.wrap(null);
}
return retval;
}
catch(TemplateModelException e)
{
throw e;
}
catch(Exception e)
{
throw new _TemplateModelException(e, new Object [] {
"An error has occurred when reading existing sub-variable ", new _DelayedJQuote(key),
"; see cause exception! The type of the containing value was: ",
new _DelayedFTLTypeDescription(this)
});
}
}
private void logNoSuchKey(String key, Map keyMap)
{
logger.debug("Key " + StringUtil.jQuoteNoXSS(key) + " was not found on instance of " +
object.getClass().getName() + ". Introspection information for " +
"the class is: " + keyMap);
}
/**
* Whether the model has a plain get(String) or get(Object) method
*/
protected boolean hasPlainGetMethod() {
return wrapper.getClassIntrospector().get(object.getClass()).get(ClassIntrospector.GENERIC_GET_KEY) != null;
}
private TemplateModel invokeThroughDescriptor(Object desc, Map classInfo)
throws
IllegalAccessException,
InvocationTargetException,
TemplateModelException
{
// See if this particular instance has a cached implementation
// for the requested feature descriptor
TemplateModel member;
synchronized(this) {
if(memberMap != null) {
member = (TemplateModel)memberMap.get(desc);
}
else {
member = null;
}
}
if(member != null)
return member;
TemplateModel retval = UNKNOWN;
if(desc instanceof IndexedPropertyDescriptor)
{
Method readMethod =
((IndexedPropertyDescriptor)desc).getIndexedReadMethod();
retval = member =
new SimpleMethodModel(object, readMethod,
ClassIntrospector.getArgTypes(classInfo, readMethod), wrapper);
}
else if(desc instanceof PropertyDescriptor)
{
PropertyDescriptor pd = (PropertyDescriptor)desc;
retval = wrapper.invokeMethod(object, pd.getReadMethod(), null);
// (member == null) condition remains, as we don't cache these
}
else if(desc instanceof Field)
{
retval = wrapper.wrap(((Field)desc).get(object));
// (member == null) condition remains, as we don't cache these
}
else if(desc instanceof Method)
{
Method method = (Method)desc;
retval = member = new SimpleMethodModel(object, method,
ClassIntrospector.getArgTypes(classInfo, method), wrapper);
}
else if(desc instanceof OverloadedMethods)
{
retval = member =
new OverloadedMethodsModel(object, (OverloadedMethods) desc, wrapper);
}
// If new cacheable member was created, cache it
if(member != null) {
synchronized(this) {
if(memberMap == null) {
memberMap = new HashMap();
}
memberMap.put(desc, member);
}
}
return retval;
}
void clearMemberCache() {
synchronized(this) {
memberMap = null;
}
}
protected TemplateModel invokeGenericGet(Map keyMap, Class clazz, String key)
throws
IllegalAccessException,
InvocationTargetException,
TemplateModelException
{
Method genericGet = (Method)keyMap.get(ClassIntrospector.GENERIC_GET_KEY);
if(genericGet == null)
return UNKNOWN;
return wrapper.invokeMethod(object, genericGet, new Object[] { key });
}
protected TemplateModel wrap(Object obj)
throws TemplateModelException
{
return wrapper.getOuterIdentity().wrap(obj);
}
protected Object unwrap(TemplateModel model)
throws
TemplateModelException
{
return wrapper.unwrap(model);
}
/**
* Tells whether the model is empty. It is empty if either the wrapped
* object is null, or it's a Boolean with false value.
*/
public boolean isEmpty()
{
if (object instanceof String) {
return ((String) object).length() == 0;
}
if (object instanceof Collection) {
return ((Collection) object).isEmpty();
}
if (object instanceof Map) {
return ((Map) object).isEmpty();
}
return object == null || Boolean.FALSE.equals(object);
}
/**
* Returns the same as {@link #getWrappedObject()}; to ensure that, this method will be final starting from 2.4.
* This behavior of {@link BeanModel} is assumed by some FreeMarker code.
*/
public Object getAdaptedObject(Class hint) {
return object; // return getWrappedObject(); starting from 2.4
}
public Object getWrappedObject() {
return object;
}
public int size()
{
return wrapper.getClassIntrospector().keyCount(object.getClass());
}
public TemplateCollectionModel keys()
{
return new CollectionAndSequence(new SimpleSequence(keySet(), wrapper));
}
public TemplateCollectionModel values() throws TemplateModelException
{
List values = new ArrayList(size());
TemplateModelIterator it = keys().iterator();
while (it.hasNext()) {
String key = ((TemplateScalarModel)it.next()).getAsString();
values.add(get(key));
}
return new CollectionAndSequence(new SimpleSequence(values, wrapper));
}
/**
* Used for {@code classic_compatbile} mode; don't use it for anything else.
* In FreeMarker 1.7 (and also at least in 2.1) {@link BeanModel} was a {@link TemplateScalarModel}. Some internal
* FreeMarker code tries to emulate FreeMarker classic by calling this method when a {@link TemplateScalarModel} is
* expected.
*/
String getAsClassicCompatibleString() {
return object == null ? "null" : object.toString();
}
public String toString() {
return object.toString();
}
/**
* Helper method to support TemplateHashModelEx. Returns the Set of
* Strings which are available via the TemplateHashModel
* interface. Subclasses that override invokeGenericGet to
* provide additional hash keys should also override this method.
*/
protected Set keySet()
{
return wrapper.getClassIntrospector().keySet(object.getClass());
}
}