/*
* Copyright 2005 Joe Walker
*
* 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 org.directwebremoting.impl;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.TreeMap;
import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import org.directwebremoting.Container;
import org.directwebremoting.extend.ContainerConfigurationException;
import org.directwebremoting.extend.UninitializingBean;
import org.directwebremoting.util.LocalUtil;
import org.directwebremoting.util.Loggers;
/**
* DefaultContainer is like a mini-IoC container for DWR.
* At least it is an IoC container by interface (check: no params that have
* anything to do with DWR), but it is hard coded specifically for DWR. If we
* want to make more of it we can later, but this is certainly not going to
* become a full blown IoC container.
* @author Joe Walker [joe at getahead dot ltd dot uk]
*/
public class DefaultContainer extends AbstractContainer implements Container
{
/**
* Set the class that should be used to implement the given interface
* @param base The interface to implement
* @param bean The new implementation
* @throws ContainerConfigurationException If the specified beans could not be used
*/
public <T> void addBean(Class<T> base, T bean)
{
addParameter(LocalUtil.originalDwrClassName(base.getName()), bean);
}
/**
* Set the class that should be used to implement the given interface
* @param base The interface to implement
* @param implementation The new implementation
* @throws ContainerConfigurationException If the specified beans could not be used
*/
public <T> void addImplementation(Class<T> base, Class<? extends T> implementation)
{
addParameter(LocalUtil.originalDwrClassName(base.getName()), implementation.getName());
}
/**
* Set the class that should be used to implement the given interface
* @param base The interface to implement
* @param implementation The new implementation
* @throws ContainerConfigurationException If the specified beans could not be used
*/
public <T> void addImplementationOption(Class<T> base, Class<? extends T> implementation)
{
Object existingOptions = beans.get(base.getName());
if (existingOptions == null)
{
beans.put(LocalUtil.originalDwrClassName(base.getName()), implementation.getName());
}
else
{
beans.put(LocalUtil.originalDwrClassName(base.getName()), existingOptions + " " + implementation.getName());
}
}
/**
* Add a parameter to the container as a possibility for injection
* @param askFor The key that will be looked up
* @param valueParam The value to be returned from the key lookup
* @throws ContainerConfigurationException If the specified beans could not be used
*/
public void addParameter(String askFor, Object valueParam) throws ContainerConfigurationException
{
Object value = valueParam;
// Maybe the value is a classname that needs instantiating
if (value instanceof String)
{
try
{
Class<?> impl = LocalUtil.classForName((String) value);
value = impl.newInstance();
}
catch (ClassNotFoundException ex)
{
// it's not a classname, leave it
}
catch (InstantiationException ex)
{
throw new ContainerConfigurationException("Unable to instantiate " + value);
}
catch (IllegalAccessException ex)
{
throw new ContainerConfigurationException("Unable to access " + value);
}
}
// If we have an instantiated value object and askFor is an interface
// then we can check that one implements the other
if (!(value instanceof String))
{
try
{
Class<?> iface = LocalUtil.classForName(askFor);
if (!iface.isAssignableFrom(value.getClass()))
{
Loggers.STARTUP.error("Can't cast: " + value + " to " + askFor);
}
}
catch (ClassNotFoundException ex)
{
// it's not a classname, leave it
}
}
if (Loggers.STARTUP.isDebugEnabled())
{
if (value instanceof String)
{
Loggers.STARTUP.debug("- value: " + askFor + " = " + value);
}
else
{
Loggers.STARTUP.debug("- impl: " + askFor + " = " + value.getClass().getName());
}
}
beans.put(askFor, value);
}
/**
* Retrieve a previously set parameter
* @param name The parameter name to retrieve
* @return The value of the specified parameter, or null if one is not set
*/
public String getParameter(String name)
{
Object value = beans.get(name);
return (value == null) ? null : value.toString();
}
/**
* Called to indicate that we finished adding parameters.
* The thread safety of a large part of DWR depends on this function only
* being called from {@link Servlet#init(javax.servlet.ServletConfig)},
* where all the setup is done, and where we depend on the undocumented
* feature of all servlet containers that they complete the init process
* of a Servlet before they begin servicing requests.
* @see DefaultContainer#addParameter(String, Object)
* @noinspection UnnecessaryLabelOnContinueStatement
*/
public void setupFinished()
{
// We try to autowire each bean in turn
for (Object bean : beans.values())
{
initializeBean(bean);
}
callInitializingBeans();
}
/* (non-Javadoc)
* @see org.directwebremoting.Container#newInstance(java.lang.Class)
*/
public <T> T newInstance(Class<T> type) throws InstantiationException, IllegalAccessException
{
T t = type.newInstance();
initializeBean(t);
return t;
}
/* (non-Javadoc)
* @see org.directwebremoting.Container#initializeBean(java.lang.Object)
*/
public void initializeBean(Object bean)
{
// HACK: It wouldn't be a good idea to start injecting into objects
// created by the app-server. Currently this is just ServletContext
// and ServletConfig. If it is others in the future then we'll need a
// better way of marking objects that should not be injected into.
// It's worth remembering that the Container is itself in the container
// so there is a vague risk of recursion here if we're not careful
if (bean instanceof ServletContext || bean instanceof ServletConfig)
{
Loggers.STARTUP.debug("- skipping injecting into: " + bean.getClass().getName());
return;
}
if (!(bean instanceof String))
{
Loggers.STARTUP.debug("- autowire: " + bean.getClass().getName());
Method[] methods = bean.getClass().getMethods();
methods:
for (Method setter : methods)
{
if (setter.getName().startsWith("set") &&
setter.getName().length() > 3 &&
setter.getParameterTypes().length == 1)
{
String name = Character.toLowerCase(setter.getName().charAt(3)) + setter.getName().substring(4);
Class<?> propertyType = setter.getParameterTypes()[0];
// First we try auto-wire by name
Object setting = beans.get(name);
if (setting != null)
{
if (propertyType.isAssignableFrom(setting.getClass()))
{
Loggers.STARTUP.debug(" - by name: " + name + " = " + setting);
invoke(setter, bean, setting);
continue methods;
}
else if (setting.getClass() == String.class)
{
try
{
Object value = LocalUtil.simpleConvert((String) setting, propertyType);
Loggers.STARTUP.debug(" - by name: " + name + " = " + value);
invoke(setter, bean, value);
}
catch (IllegalArgumentException ex)
{
// Ignore - this was a speculative convert anyway
}
continue methods;
}
}
// Next we try autowire-by-type
Object value = beans.get(LocalUtil.originalDwrClassName(propertyType.getName()));
if (value != null)
{
Loggers.STARTUP.debug(" - by type: " + name + " = " + value.getClass().getName());
invoke(setter, bean, value);
continue methods;
}
Loggers.STARTUP.debug(" - no properties for: " + name);
}
}
}
}
/**
* A helper to do the reflection.
* This helper throws away all exceptions, preferring to log.
* @param setter The method to invoke
* @param bean The object to invoke the method on
* @param value The value to assign to the property using the setter method
*/
private static void invoke(Method setter, Object bean, Object value)
{
try
{
setter.invoke(bean, value);
}
catch (InvocationTargetException ex)
{
Loggers.STARTUP.error(" - Exception during auto-wire: ", ex.getTargetException());
}
catch (Exception ex)
{
Loggers.STARTUP.error(" - Error calling setter: " + setter, ex);
}
}
/* (non-Javadoc)
* @see org.directwebremoting.Container#getBean(java.lang.String)
*/
public Object getBean(String id)
{
return beans.get(id);
}
/* (non-Javadoc)
* @see org.directwebremoting.Container#getBeanNames()
*/
public Collection<String> getBeanNames()
{
return Collections.unmodifiableCollection(beans.keySet());
}
/* (non-Javadoc)
* @see org.directwebremoting.Container#contextDestroyed()
*/
public void contextDestroyed()
{
contextDestroyed(getBeanNames());
}
public void contextDestroyed(Collection<String> beanNames)
{
Loggers.STARTUP.debug("ContextDestroyed for container: " + getClass().getSimpleName());
for (String beanName : beanNames)
{
Object bean = getBean(beanName);
if (bean instanceof UninitializingBean && !(bean instanceof Container))
{
UninitializingBean scl = (UninitializingBean) bean;
Loggers.STARTUP.debug("- For contained bean: " + beanName);
scl.contextDestroyed();
}
}
}
/* (non-Javadoc)
* @see org.directwebremoting.Container#servletDestroyed()
*/
public void servletDestroyed()
{
servletDestroyed(getBeanNames());
}
/* (non-Javadoc)
* @see org.directwebremoting.Container#servletDestroyed()
*/
public void servletDestroyed(Collection<String> beanNames)
{
Loggers.STARTUP.debug("ServletDestroyed for container: " + getClass().getSimpleName());
for (String beanName : beanNames)
{
Object bean = getBean(beanName);
if (bean instanceof UninitializingBean && !(bean instanceof Container))
{
UninitializingBean scl = (UninitializingBean) bean;
Loggers.STARTUP.debug("- For contained bean: " + beanName);
scl.servletDestroyed();
}
}
}
/**
* The beans that we know of indexed by type
*/
protected Map<String, Object> beans = new TreeMap<String, Object>();
}