/*
* Copyright 2009-2012 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 org.apache.ibatis.io;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
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.
* 通过类加载器获得resource的辅助类
*
* @author Clinton Begin
*/
public class Resources {
//大多数方法都是委托给ClassLoaderWrapper，再去做真正的事
private static ClassLoaderWrapper classLoaderWrapper = new ClassLoaderWrapper();
/*
* Charset to use when calling getResourceAsReader.
* null means use the system default.
*/
private static Charset charset;
Resources() {
}
/*
* Returns the default classloader (may be null).
*
* @return The default classloader
*/
public static ClassLoader getDefaultClassLoader() {
return classLoaderWrapper.defaultClassLoader;
}
/*
* Sets the default classloader
*
* @param defaultClassLoader - the new default ClassLoader
*/
public static void setDefaultClassLoader(ClassLoader defaultClassLoader) {
classLoaderWrapper.defaultClassLoader = defaultClassLoader;
}
/*
* Returns the URL of the resource on the classpath
*
* @param resource The resource to find
* @return The resource
* @throws java.io.IOException If the resource cannot be found or read
*/
public static URL getResourceURL(String resource) throws IOException {
// issue #625
return getResourceURL(null, resource);
}
/*
* Returns the URL of the resource on the classpath
*
* @param loader The classloader used to fetch the resource
* @param resource The resource to find
* @return The resource
* @throws java.io.IOException If the resource cannot be found or read
*/
public static URL getResourceURL(ClassLoader loader, String resource) throws IOException {
URL url = classLoaderWrapper.getResourceAsURL(resource, loader);
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 java.io.IOException If the resource cannot be found or read
*/
public static InputStream getResourceAsStream(String resource) throws IOException {
return getResourceAsStream(null, resource);
}
/*
* Returns a resource on the classpath as a Stream object
*
* @param loader The classloader used to fetch the resource
* @param resource The resource to find
* @return The resource
* @throws java.io.IOException If the resource cannot be found or read
*/
public static InputStream getResourceAsStream(ClassLoader loader, String resource) throws IOException {
InputStream in = classLoaderWrapper.getResourceAsStream(resource, loader);
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 java.io.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 fetch the resource
* @param resource The resource to find
* @return The resource
* @throws java.io.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 java.io.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 fetch the resource
* @param resource The resource to find
* @return The resource
* @throws java.io.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 java.io.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 fetch the resource
* @param resource - the resource to find
* @return The resource
* @throws java.io.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 java.io.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 java.io.IOException If the resource cannot be found or read
*/
public static Reader getUrlAsReader(String urlString) throws IOException {
Reader reader;
if (charset == null) {
reader = new InputStreamReader(getUrlAsStream(urlString));
} else {
reader = new InputStreamReader(getUrlAsStream(urlString), charset);
}
return reader;
}
/*
* Gets a URL as a Properties object
*
* @param urlString - the URL to get
* @return A Properties object with the data from the URL
* @throws java.io.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 fetch
* @return The loaded class
* @throws ClassNotFoundException If the class cannot be found (duh!)
*/
public static Class<?> classForName(String className) throws ClassNotFoundException {
return classLoaderWrapper.classForName(className);
}
public static Charset getCharset() {
return charset;
}
public static void setCharset(Charset charset) {
Resources.charset = charset;
}
}