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Annotation based auto wiring of wicket components.
The newest version!
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with this
* work for additional information regarding copyright ownership. The ASF
* licenses this file to You 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 com.github.wicket.autowire;
import static java.util.Map.Entry;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.Stack;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicReference;
import org.apache.wicket.Application;
import org.apache.wicket.Component;
import org.apache.wicket.MarkupContainer;
import org.apache.wicket.WicketRuntimeException;
import org.apache.wicket.application.IComponentInitializationListener;
import org.apache.wicket.application.IComponentInstantiationListener;
import org.apache.wicket.markup.ComponentTag;
import org.apache.wicket.markup.IMarkupFragment;
import org.apache.wicket.markup.MarkupElement;
import org.apache.wicket.markup.MarkupNotFoundException;
import org.apache.wicket.markup.MarkupStream;
import org.apache.wicket.markup.WicketTag;
import org.apache.wicket.markup.html.TransparentWebMarkupContainer;
import org.apache.wicket.markup.html.border.Border;
import org.apache.wicket.markup.html.list.ListItem;
import org.apache.wicket.markup.resolver.WicketContainerResolver;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public final class AutoWire implements IComponentInitializationListener, IComponentInstantiationListener {
private static final Logger log = LoggerFactory.getLogger(AutoWire.class);
private static final ComponentCache cache = new ComponentCache();
private AutoWire() {
}
public static void install(final Application application) {
final AutoWire instance = new AutoWire();
application.getComponentInitializationListeners().add(instance);
application.getComponentInstantiationListeners().add(instance);
}
@Override
public void onInstantiation(final Component component) {
Value value = cache.get(component.getClass());
if (value == null) {
if (log.isTraceEnabled()) {
log.trace("Cache miss");
}
synchronized (AutoWire.class) {
value = cache.get(component.getClass());
if (value == null) {
value = getInstantiationActions(component);
cache.put(component.getClass(), value);
}
}
}
value.performInstantiationActions(component);
}
boolean hasAutoComponentAnnotatedFields(Class clazz) {
synchronized (AutoWire.class) {
return cache.get(clazz).hasAutoComponentAnnotatedFields;
}
}
private Value getInstantiationActions(Component component) {
List actions = new ArrayList();
boolean foundAnnotationAutoComponent = false;
if (isAutoWiringPossible(component)) {
Set done = new HashSet();
Class clazz = component.getClass();
// iterate over class hierarchy
while (Component.class.isAssignableFrom(clazz)) {
if (log.isTraceEnabled()) {
log.trace("looking for fields in class " + clazz);
}
// iterate over declared fields
for (final Field field : clazz.getDeclaredFields()) {
if (field.isAnnotationPresent(AutoComponent.class)) {
foundAnnotationAutoComponent = true;
AutoComponent ann = field.getAnnotation(AutoComponent.class);
if (ann.inject()) {
final String id = ann.id().isEmpty() ? field.getName() : ann.id();
// fields in super classes are ignored, if they are in subclasses too
if (!done.contains(id)) {
done.add(id);
Component value = getValue(component, field);
if (value == null) {
actions.add(new AssignInstanceAction(field, id));
}
else {
if (log.isTraceEnabled()) {
log.trace("Field " + field.getName() + " is already initialized. skipping.");
}
}
}
}
}
}
clazz = clazz.getSuperclass();
}
}
if (log.isTraceEnabled()) {
log.trace("Actions: " + actions);
}
return new Value(actions, foundAnnotationAutoComponent);
}
private static Component getValue(Component component, Field field) {
boolean accessible = field.isAccessible();
field.setAccessible(true);
try {
Component value = (Component) field.get(component);
field.setAccessible(accessible);
return value;
}
catch (IllegalAccessException e) {
return null;
}
}
@Override
public void onInitialize(final Component component) {
if (isAutoWiringPossible(component)) {
try {
Value value = cache.get(component.getClass());
value.performInitializeActions(component);
}
catch (final MarkupNotFoundException e) {
//Nothing to do
}
}
}
private boolean isAutoWiringPossible(final Component component) {
return component instanceof MarkupContainer && !(component instanceof TransparentWebMarkupContainer);
}
private static Component buildComponent(Component component, final String id, Node child) {
Class clazz = component.getClass();
while (Component.class.isAssignableFrom(clazz)) {
Component value = null;
// look for annotated field
for (Field iter : clazz.getDeclaredFields()) {
if (iter.isAnnotationPresent(AutoComponent.class)) {
value = getValue(component, iter);
if (value != null && value.getId().equals(id)) {
child.field = iter;
break;
}
else {
value = null;
}
}
}
if (value != null) {
return value;
}
clazz = clazz.getSuperclass();
}
return null;
}
// set value on duplicated field of parent classes too!
private static void setValue(Component instance,
final Component component,
Field field) throws IllegalAccessException {
Class clazz = field.getDeclaringClass();
while (Component.class.isAssignableFrom(clazz)) {
for (Field f : clazz.getDeclaredFields()) {
if (f.getName().equals(field.getName())) {
boolean accessible = f.isAccessible();
f.setAccessible(true);
f.set(component, instance);
f.setAccessible(accessible);
}
}
clazz = clazz.getSuperclass();
}
}
private Component getInstance(final Class componentClass,
final Component enclosing,
final String id) throws NoSuchMethodException,
InstantiationException,
IllegalAccessException,
IllegalArgumentException,
InvocationTargetException {
if (componentClass.getEnclosingClass() == null || Modifier.isStatic(componentClass.getModifiers())) {
// -- Static inner class or normal class
final Constructor constructor = componentClass.getDeclaredConstructor(String.class);
constructor.setAccessible(true);
return (Component) constructor.newInstance(id);
}
else {
if (enclosing != null && componentClass.getEnclosingClass().isAssignableFrom(enclosing.getClass())) {
final Constructor constructor = componentClass.getDeclaredConstructor(componentClass.getEnclosingClass(),
String.class);
constructor.setAccessible(true);
return (Component) constructor.newInstance(enclosing, id);
}
throw new RuntimeException("Unable to initialize inner class "
+ componentClass.getClass().getSimpleName() + " with id " + id
+ ". Enclosing class is not in the component hierarchy.");
}
}
private static class Value {
private static final int THRESHOLD_MILLIS = 8 * 24 * 60 * 60 * 1000;
private final Map cache = new ConcurrentHashMap();
private final List instantiationActions;
private final boolean hasAutoComponentAnnotatedFields;
public Value(List instantiationActions, boolean hasAutoComponentAnnotatedFields) {
this.instantiationActions = instantiationActions;
this.hasAutoComponentAnnotatedFields = hasAutoComponentAnnotatedFields;
}
public void performInstantiationActions(Component component) {
for (Action action : instantiationActions) {
action.perform(component);
}
}
public void performInitializeActions(Component component) {
if (!hasAutoComponentAnnotatedFields) {
return;
}
final IMarkupFragment markup = ((MarkupContainer) component).getMarkup(null);
if (markup == null) {
return;
}
String key = markup.toString(false);
Node node = cache.get(key);
if (node == null) {
if (log.isTraceEnabled()) {
log.trace("MARKUP MISS");
}
synchronized (AutoWire.class) {
node = cache.get(key);
if (node == null) {
node = getNode(component, markup);
cache.put(key, node);
}
}
}
node.lastUsed = System.currentTimeMillis();
node.initialize(component);
cleanup();
}
// avoid memory leaks if markup changes often.
private void cleanup() {
if (cache.size() > 30) {
long threshold = System.currentTimeMillis() - THRESHOLD_MILLIS;
for (Iterator> iterator = cache.entrySet().iterator(); iterator.hasNext();) {
Entry next = iterator.next();
if (next.getValue().lastUsed < threshold) {
iterator.remove();
}
}
}
}
private Node getNode(Component component, IMarkupFragment markup) {
final MarkupStream stream = new MarkupStream(markup);
final Stack> stack = new Stack>();
stack.push(new AtomicReference(component));
Node node = new Node();
// detect borders.
boolean addToBorder = false;
if (log.isTraceEnabled()) {
log.trace("Performing auto wiring for component " + component);
}
// no associated markup: component tag is part of the markup
MarkupElement containerTag = null;
//TODO current criteria is fragile! find better way to check if component tag of component is part its markup.
if (skipFirstComponentTag(component, stream)) {
if (log.isTraceEnabled()) {
log.trace("Skipped component tag " + stream.get());
}
containerTag = stream.get();
stream.next();
}
while (stream.skipUntil(ComponentTag.class)) {
final ComponentTag tag = stream.getTag();
if (log.isTraceEnabled()) {
log.trace("Processing tag " + tag);
}
// track border tags
if (tag instanceof WicketTag) {
if (((WicketTag) tag).isBorderTag() && tag.isOpen()) {
addToBorder = true;
}
else if (((WicketTag) tag).isBodyTag() && tag.isOpen()) {
addToBorder = false;
}
else if (((WicketTag) tag).isBodyTag() && tag.isClose()) {
addToBorder = true;
}
else if (((WicketTag) tag).isBorderTag() && tag.isClose()) {
addToBorder = false;
}
}
if (log.isTraceEnabled()) {
log.trace("addToBorder? " + addToBorder);
}
// maintain bread crumbs and build components
if (isComponentTag(tag)) {
if (tag.isOpen() || tag.isOpenClose()) {
final Component container = stack.peek().get();
final Component cmp;
final Node child = new Node();
if (log.isTraceEnabled()) {
log.trace("Current parent component is " + container);
}
if (container == null) {
cmp = null;
}
else {
cmp = buildComponent(component, tag.getId(), child);
}
if (log.isTraceEnabled()) {
log.trace("Resolved component is " + cmp + ". Adding to parent now.");
}
if (cmp != null) {
if (container instanceof MarkupContainer) {
if (addToBorder && container instanceof Border) {
child.border = true;
}
else {
child.border = false;
}
child.id = cmp.getId();
node.add(child);
}
else if (container == null) {
throw new RuntimeException("component " + tag.getId()
+ " was auto wired, but its parent not!");
}
else {
throw new RuntimeException("only containers may contain child elements. type of " + container
+ " is not a container!");
}
}
// push even if cmp is null, to track if parent is auto-wired
if (tag.isOpen() && !tag.hasNoCloseTag()) {
if (log.isTraceEnabled()) {
log.trace("Tag has a body. Adding to stack now.");
}
stack.push(new AtomicReference(cmp));
if (cmp != null) {
node = child;
}
if (log.isTraceEnabled()) {
log.trace("Current stack: " + stack);
}
}
}
else if (tag.isClose() && !tag.getOpenTag().isAutoComponentTag()) {
// the container tag is part of the inherited markup. do not pop stack on container tag close.
if (containerTag == null || !tag.closes(containerTag)) {
if (log.isTraceEnabled()) {
log.trace("Tag is closing. Pop the stack now.");
}
if (stack.pop().get() != null) {
node = node.parent;
}
if (log.isTraceEnabled()) {
log.trace("Current stack: " + stack);
}
}
}
}
if (log.isTraceEnabled()) {
log.trace("--- Tag done. ---");
}
stream.next();
}
if (stack.size() != 1) {
throw new RuntimeException("Stack must only contain one element " + stack);
}
return node;
}
private boolean skipFirstComponentTag(Component component, MarkupStream stream) {
if (stream.get() instanceof ComponentTag
&& ((ComponentTag) stream.get()).getId().equals(component.getId())) {
return true;
}
else if (component instanceof ListItem) {
return true;
}
else {
return false;
}
}
private boolean isComponentTag(ComponentTag tag) {
return !(tag instanceof WicketTag) && !tag.isAutoComponentTag()
|| tag.getName().equals(WicketContainerResolver.CONTAINER);
}
}
private static class ComponentCache extends ConcurrentHashMap, Value> {
}
private static class Node {
Node parent = null;
Field field = null;
List childNodes = new ArrayList();
boolean border = false;
public String id = null;
long lastUsed = System.currentTimeMillis();
public void add(Node child) {
child.parent = this;
childNodes.add(child);
}
@Override
public String toString() {
return "Node{" + "field=" + ((field != null) ? field.getName() : null) + ", childNodes=" + childNodes
+ ", border=" + border + ", id='" + id + '\'' + '}';
}
public void initialize(Component component) {
initialize(component, component);
}
private void initialize(Component root, Component parent) {
for (Node child : childNodes) {
Component value = getValue(root, child.field);
if (child.border) {
((Border) parent).addToBorder(value);
}
else {
((MarkupContainer) parent).add(value);
}
if (!child.childNodes.isEmpty()) {
child.initialize(root, value);
}
}
}
}
private interface Action {
void perform(Component component);
}
private class AssignInstanceAction implements Action {
private final Field field;
private final String id;
public AssignInstanceAction(Field field, String id) {
this.field = field;
this.id = id;
}
@Override
public String toString() {
return "Assign instance with id " + id + " to field " + field.getName();
}
@Override
public void perform(Component component) {
try {
Component instance = getInstance(field.getType(), component, id);
setValue(instance, component, field);
}
catch (NoSuchMethodException e) {
throw new WicketRuntimeException(e);
}
catch (InstantiationException e) {
throw new WicketRuntimeException(e);
}
catch (IllegalAccessException e) {
throw new WicketRuntimeException(e);
}
catch (InvocationTargetException e) {
throw new WicketRuntimeException(e);
}
}
}
}