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/*
* Copyright 2004 Clinton Begin
*
* 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 top.jfunc.common.db.scriptrunner;
import java.io.*;
import java.net.URL;
import java.net.URLConnection;
import java.util.Properties;
/**
* A class to simplify access to resources through the classloader.
* @author Clinton Begin
*/
public class Resources{
private static ClassLoader defaultClassLoader;
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 = getResourceAsStream(resource);
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 = getResourceAsStream(loader, resource);
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{
return new InputStreamReader(getResourceAsStream(resource));
}
/**
* 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{
return new InputStreamReader(getResourceAsStream(loader, resource));
}
/**
* 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 = getUrlAsStream(urlString);
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();
}
}
}
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