/*
* 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 myjava.beans;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.net.MalformedURLException;
import java.net.URL;
import org.apache.harmony.beans.internal.nls.Messages;
/**
* This class <code>Beans</code> provides some methods for manipulting bean
* controls.
*
*/
public class Beans {
private static boolean designTime = false;
private static boolean guiAvailable = true;
/**
* Constructs a Beans instance.
*/
public Beans() {
// expected
}
@SuppressWarnings("unchecked")
private static Object internalInstantiate(ClassLoader cls, String beanName, Object initializer) throws IOException,
ClassNotFoundException {
// First try to load it from a serialization file.
String beanResourceName = getBeanResourceName(beanName);
InputStream is = (cls == null) ? ClassLoader
.getSystemResourceAsStream(beanResourceName) : cls
.getResourceAsStream(beanResourceName);
IOException serializationException = null;
Object result = null;
if (is != null) {
try {
ObjectInputStream ois = (cls == null) ? new ObjectInputStream(
is) : new CustomizedObjectInputStream(is, cls);
result = ois.readObject();
} catch (IOException e) {
// Not loadable - remember this as we may throw it later.
serializationException = e;
}
}
// If it didn't work, try to instantiate it from the given classloader
boolean deserialized = true;
ClassLoader classLoader = cls == null ? ClassLoader
.getSystemClassLoader() : cls;
if (result == null) {
deserialized = false;
try {
result = Class.forName(beanName, true, classLoader)
.newInstance();
} catch (Exception e) {
if (serializationException != null) {
throw serializationException;
}
throw new ClassNotFoundException(e.getClass() + ": " //$NON-NLS-1$
+ e.getMessage());
}
}
return result;
}
/**
* Obtains an instance of a JavaBean specified the bean name using the
* specified class loader.
* <p>
* If the specified class loader is null, the system class loader is used.
* </p>
*
* @param loader
* the specified class loader. It can be null.
* @param name
* the name of the JavaBean
* @return an isntance of the bean.
* @throws IOException
* @throws ClassNotFoundException
*/
public static Object instantiate(ClassLoader loader, String name)
throws IOException, ClassNotFoundException {
return internalInstantiate(loader, name, null);
}
/**
* Obtain an alternative type view of the given bean. The view type is
* specified by the parameter <code>type</code>.
* <p>
* If the type view cannot be obtained, the original bean object is
* returned.
* </p>
*
* @param bean
* the original bean object.
* @param targetType
* the specified view type.
* @return a type view of the given bean.
*/
public static Object getInstanceOf(Object bean, Class<?> targetType) {
return bean;
}
/**
* Determine if the the specified bean object can be viewed as the specified
* type.
*
* @param bean
* the specified bean object.
* @param targetType
* the specifed view type.
* @return true if the specified bean object can be viewed as the specified
* type; otherwise, return false;
*/
public static boolean isInstanceOf(Object bean, Class<?> targetType) {
if (bean == null) {
throw new NullPointerException(Messages.getString("beans.1D")); //$NON-NLS-1$
}
return targetType == null ? false : targetType.isInstance(bean);
}
/**
* Set whether or not a GUI is available in the bean's current environment.
*
* @param isGuiAvailable
* should be <code>true</code> to signify that a GUI is
* available, <code>false</code> otherwise.
* @throws SecurityException
* if the caller does not have the required permission to access
* or modify system properties.
*/
public static synchronized void setGuiAvailable(boolean isGuiAvailable)
throws SecurityException {
checkPropertiesAccess();
guiAvailable = isGuiAvailable;
}
/**
* Used to indicate whether of not it's in an application construction
* environment.
*
* @param isDesignTime
* true to indicate that it's in application construction
* environment.
* @throws SecurityException
*/
public static void setDesignTime(boolean isDesignTime)
throws SecurityException {
checkPropertiesAccess();
synchronized(Beans.class){
designTime = isDesignTime;
}
}
/**
* Returns a boolean indication of whether or not a GUI is available for
* beans.
*
* @return <code>true</code> if a GUI is available, otherwise
* <code>false</code>.
*/
public static synchronized boolean isGuiAvailable() {
return guiAvailable;
}
/**
* Determine if it's in design-mode.
*
* @return true if it's in an application construction environment.
*/
public static synchronized boolean isDesignTime() {
return designTime;
}
private static void checkPropertiesAccess() throws SecurityException {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPropertiesAccess();
}
}
private static String getBeanResourceName(String beanName) {
return beanName.replace('.', '/') + ".ser"; //$NON-NLS-1$
}
// Maps malformed URL exception to ClassNotFoundException
private static URL safeURL(String urlString) throws ClassNotFoundException {
try {
return new URL(urlString);
} catch (MalformedURLException exception) {
throw new ClassNotFoundException(exception.getMessage());
}
}
}