org.tinygroup.commons.tools.Resources Maven / Gradle / Ivy
/**
* Copyright (c) 1997-2013, www.tinygroup.org ([email protected]).
*
* Licensed under the GPL, Version 3.0 (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.gnu.org/licenses/gpl.html
*
* 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.tinygroup.commons.tools;
import java.io.*;
import java.net.URL;
import java.net.URLConnection;
import java.nio.charset.Charset;
import java.util.Properties;
/**
* A class to simplify access to resources through the classloader.
*/
public final class Resources{
private static ClassLoader defaultClassLoader;
/**
* Charset to use when calling getResourceAsReader. null means use the
* system default.
*/
private static Charset charset;
private Resources() {
}
/**
* Returns the default classloader (may be null).
*
* @return The default classloader
*/
public static ClassLoader getDefaultClassLoader() {
return defaultClassLoader;
}
/**
* Sets the default classloader
*
* @param defaultClassLoader
* - the new default ClassLoader
*/
public static void setDefaultClassLoader(ClassLoader defaultClassLoader) {
Resources.defaultClassLoader = defaultClassLoader;
}
/**
* Returns the URL of the resource on the classpath
*
* @param resource
* The resource to find
* @return The resource
* @throws IOException
* If the resource cannot be found or read
*/
public static URL getResourceURL(String resource) throws IOException {
return getResourceURL(getClassLoader(), resource);
}
/**
* Returns the URL of the resource on the classpath
*
* @param loader
* The classloader used to load the resource
* @param resource
* The resource to find
* @return The resource
* @throws IOException
* If the resource cannot be found or read
*/
public static URL getResourceURL(ClassLoader loader, String resource)
throws IOException {
URL url = null;
if (loader != null){
url = loader.getResource(resource);
}
if (url == null){
url = ClassLoader.getSystemResource(resource);
}
if (url == null){
throw new IOException("Could not find resource " + resource);
}
return url;
}
/**
* Returns a resource on the classpath as a Stream object
*
* @param resource
* The resource to find
* @return The resource
* @throws IOException
* If the resource cannot be found or read
*/
public static InputStream getResourceAsStream(String resource)
throws IOException {
return getResourceAsStream(getClassLoader(), resource);
}
/**
* Returns a resource on the classpath as a Stream object
*
* @param loader
* The classloader used to load the resource
* @param resource
* The resource to find
* @return The resource
* @throws IOException
* If the resource cannot be found or read
*/
public static InputStream getResourceAsStream(ClassLoader loader,
String resource) throws IOException {
InputStream in = null;
if (loader != null){
in = loader.getResourceAsStream(resource);
}
if (in == null){
in = ClassLoader.getSystemResourceAsStream(resource);
}
if (in == null){
throw new IOException("Could not find resource " + resource);
}
return in;
}
/**
* Returns a resource on the classpath as a Properties object
*
* @param resource
* The resource to find
* @return The resource
* @throws IOException
* If the resource cannot be found or read
*/
public static Properties getResourceAsProperties(String resource)
throws IOException {
Properties props = new Properties();
InputStream in = null;
String propfile = resource;
in = getResourceAsStream(propfile);
props.load(in);
in.close();
return props;
}
/**
* Returns a resource on the classpath as a Properties object
*
* @param loader
* The classloader used to load the resource
* @param resource
* The resource to find
* @return The resource
* @throws IOException
* If the resource cannot be found or read
*/
public static Properties getResourceAsProperties(ClassLoader loader,
String resource) throws IOException {
Properties props = new Properties();
InputStream in = null;
String propfile = resource;
in = getResourceAsStream(loader, propfile);
props.load(in);
in.close();
return props;
}
/**
* Returns a resource on the classpath as a Reader object
*
* @param resource
* The resource to find
* @return The resource
* @throws IOException
* If the resource cannot be found or read
*/
public static Reader getResourceAsReader(String resource)
throws IOException {
Reader reader;
if (charset == null) {
reader = new InputStreamReader(getResourceAsStream(resource));
} else {
reader = new InputStreamReader(getResourceAsStream(resource),
charset);
}
return reader;
}
/**
* Returns a resource on the classpath as a Reader object
*
* @param loader
* The classloader used to load the resource
* @param resource
* The resource to find
* @return The resource
* @throws IOException
* If the resource cannot be found or read
*/
public static Reader getResourceAsReader(ClassLoader loader, String resource)
throws IOException {
Reader reader;
if (charset == null) {
reader = new InputStreamReader(
getResourceAsStream(loader, resource));
} else {
reader = new InputStreamReader(
getResourceAsStream(loader, resource), charset);
}
return reader;
}
/**
* Returns a resource on the classpath as a File object
*
* @param resource
* The resource to find
* @return The resource
* @throws IOException
* If the resource cannot be found or read
*/
public static File getResourceAsFile(String resource) throws IOException {
return new File(getResourceURL(resource).getFile());
}
/**
* Returns a resource on the classpath as a File object
*
* @param loader
* - the classloader used to load the resource
* @param resource
* - the resource to find
* @return The resource
* @throws IOException
* If the resource cannot be found or read
*/
public static File getResourceAsFile(ClassLoader loader, String resource)
throws IOException {
return new File(getResourceURL(loader, resource).getFile());
}
/**
* Gets a URL as an input stream
*
* @param urlString
* - the URL to get
* @return An input stream with the data from the URL
* @throws IOException
* If the resource cannot be found or read
*/
public static InputStream getUrlAsStream(String urlString)
throws IOException {
URL url = new URL(urlString);
URLConnection conn = url.openConnection();
return conn.getInputStream();
}
/**
* Gets a URL as a Reader
*
* @param urlString
* - the URL to get
* @return A Reader with the data from the URL
* @throws IOException
* If the resource cannot be found or read
*/
public static Reader getUrlAsReader(String urlString) throws IOException {
return new InputStreamReader(getUrlAsStream(urlString));
}
/**
* Gets a URL as a Properties object
*
* @param urlString
* - the URL to get
* @return A Properties object with the data from the URL
* @throws IOException
* If the resource cannot be found or read
*/
public static Properties getUrlAsProperties(String urlString)
throws IOException {
Properties props = new Properties();
InputStream in = null;
String propfile = urlString;
in = getUrlAsStream(propfile);
props.load(in);
in.close();
return props;
}
/**
* Loads a class
*
* @param className
* - the class to load
* @return The loaded class
* @throws ClassNotFoundException
* If the class cannot be found (duh!)
*/
public static Class classForName(String className)
throws ClassNotFoundException {
Class clazz = null;
try {
clazz = getClassLoader().loadClass(className);
} catch (Exception e) {
// Ignore. Failsafe below.
}
if (clazz == null) {
clazz = Class.forName(className);
}
return clazz;
}
/**
* Creates an instance of a class
*
* @param className
* - the class to create
* @return An instance of the class
* @throws ClassNotFoundException
* If the class cannot be found (duh!)
* @throws InstantiationException
* If the class cannot be instantiaed
* @throws IllegalAccessException
* If the class is not public, or other access problems arise
*/
public static Object instantiate(String className)
throws ClassNotFoundException, InstantiationException,
IllegalAccessException {
return instantiate(classForName(className));
}
/**
* Creates an instance of a class
*
* @param clazz
* - the class to create
* @return An instance of the class
* @throws InstantiationException
* If the class cannot be instantiaed
* @throws IllegalAccessException
* If the class is not public, or other access problems arise
*/
public static Object instantiate(Class clazz)
throws InstantiationException, IllegalAccessException {
return clazz.newInstance();
}
private static ClassLoader getClassLoader() {
if (defaultClassLoader != null) {
return defaultClassLoader;
} else {
return Thread.currentThread().getContextClassLoader();
}
}
public static Charset getCharset() {
return charset;
}
/**
* Use this method to set the Charset to be used when calling the
* getResourceAsReader methods. This will allow iBATIS to function properly
* when the system default encoding doesn't deal well with unicode
* (IBATIS-340, IBATIS-349)
*
* @param charset
*/
public static void setCharset(Charset charset) {
Resources.charset = charset;
}
}
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