/*
* Copyright 2010-2011 the original author or authors.
*
* 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 com.starflow.wf.core.resource;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Properties;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.starflow.wf.engine.ProcessEngineException;
/**
* A simple class to centralize logic needed to locate config files on the system.
*
* @author Steve
*/
public final class ConfigHelper {
private static final Logger log = LoggerFactory.getLogger(ConfigHelper.class);
/** Try to locate a local URL representing the incoming path. The first attempt
* assumes that the incoming path is an actual URL string (file://, etc). If this
* does not work, then the next attempts try to locate this UURL as a java system
* resource.
*
* @param path The path representing the config location.
* @return An appropriate URL or null.
*/
public static final URL locateConfig(final String path) {
try {
return new URL(path);
}
catch(MalformedURLException e) {
return findAsResource(path);
}
}
/**
* Try to locate a local URL representing the incoming path.
* This method <b>only</b> attempts to locate this URL as a
* java system resource.
*
* @param path The path representing the config location.
* @return An appropriate URL or null.
*/
public static final URL findAsResource(final String path) {
URL url = null;
// First, try to locate this resource through the current
// context classloader.
ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
if (contextClassLoader!=null) {
url = contextClassLoader.getResource(path);
}
if (url != null)
return url;
// Next, try to locate this resource through this class's classloader
url = ConfigHelper.class.getClassLoader().getResource(path);
if (url != null)
return url;
// Next, try to locate this resource through the system classloader
url = ClassLoader.getSystemClassLoader().getResource(path);
// Anywhere else we should look?
return url;
}
/** Open an InputStream to the URL represented by the incoming path. First makes a call
* to {@link #locateConfig(java.lang.String)} in order to find an appropriate URL.
* {@link java.net.URL#openStream()} is then called to obtain the stream.
*
* @param path The path representing the config location.
* @return An input stream to the requested config resource.
* @throws HibernateException Unable to open stream to that resource.
*/
public static final InputStream getConfigStream(final String path) throws ProcessEngineException {
final URL url = ConfigHelper.locateConfig(path);
if (url == null) {
String msg = "Unable to locate config file: " + path;
log.error( msg );
throw new ProcessEngineException(msg);
}
try {
return url.openStream();
}
catch(IOException e) {
throw new ProcessEngineException("Unable to open config file: " + path, e);
}
}
/** Open an Reader to the URL represented by the incoming path. First makes a call
* to {@link #locateConfig(java.lang.String)} in order to find an appropriate URL.
* {@link java.net.URL#openStream()} is then called to obtain a stream, which is then
* wrapped in a Reader.
*
* @param path The path representing the config location.
* @return An input stream to the requested config resource.
* @throws HibernateException Unable to open reader to that resource.
*/
public static final Reader getConfigStreamReader(final String path) throws ProcessEngineException {
return new InputStreamReader( getConfigStream(path) );
}
/** Loads a properties instance based on the data at the incoming config location.
*
* @param path The path representing the config location.
* @return The loaded properties instance.
* @throws HibernateException Unable to load properties from that resource.
*/
public static final Properties getConfigProperties(String path) throws ProcessEngineException {
try {
Properties properties = new Properties();
properties.load( getConfigStream(path) );
return properties;
}
catch(IOException e) {
throw new ProcessEngineException("Unable to load properties from specified config file: " + path, e);
}
}
private ConfigHelper() {}
public static InputStream getResourceAsStream(String resource) {
String stripped = resource.startsWith("/") ?
resource.substring(1) : resource;
InputStream stream = null;
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
if (classLoader!=null) {
stream = classLoader.getResourceAsStream( stripped );
}
if ( stream == null ) {
stream = Environment.class.getResourceAsStream( resource );
}
if ( stream == null ) {
stream = Environment.class.getClassLoader().getResourceAsStream( stripped );
}
if ( stream == null ) {
throw new ProcessEngineException( resource + " not found" );
}
return stream;
}
public static InputStream getUserResourceAsStream(String resource) {
boolean hasLeadingSlash = resource.startsWith( "/" );
String stripped = hasLeadingSlash ? resource.substring(1) : resource;
InputStream stream = null;
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
if ( classLoader != null ) {
stream = classLoader.getResourceAsStream( resource );
if ( stream == null && hasLeadingSlash ) {
stream = classLoader.getResourceAsStream( stripped );
}
}
if ( stream == null ) {
stream = Environment.class.getClassLoader().getResourceAsStream( resource );
}
if ( stream == null && hasLeadingSlash ) {
stream = Environment.class.getClassLoader().getResourceAsStream( stripped );
}
if ( stream == null ) {
throw new ProcessEngineException( resource + " not found" );
}
return stream;
}
}