URLResourceUtil.java

package org.springside.modules.utils.io;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.Validate;

/**
 * 兼容url为无前缀，file://与classpath:// 三种情况的工具集
 * 
 * 参考Spring ResourceUtils
 * 
 * @author calvin
 */
public class URLResourceUtil {

	private static final String CLASSPATH_PREFIX = "classpath://";

	private static final String URL_PROTOCOL_FILE = "file";

	/**
	 * 兼容无前缀, classpath://, file:// 的情况获取文件
	 * 
	 * 如果以classpath:// 定义的文件不存在会抛出IllegalArgumentException异常，以file://定义的则不会
	 */
	public static File asFile(String generalPath) throws IOException {
		if (StringUtils.startsWith(generalPath, CLASSPATH_PREFIX)) {
			String resourceName = StringUtils.substringAfter(generalPath, CLASSPATH_PREFIX);
			return getFileByURL(ResourceUtil.asUrl(resourceName));
		}
		try {
			// try URL
			return getFileByURL(new URL(generalPath));
		} catch (MalformedURLException ex) {
			// no URL -> treat as file path
			return new File(generalPath);
		}
	}

	/**
	 * 兼容file://与classpath://的情况的打开文件成Stream
	 */
	public static InputStream asStream(String generalPath) throws IOException {
		if (StringUtils.startsWith(generalPath, CLASSPATH_PREFIX)) {
			String resourceName = StringUtils.substringAfter(generalPath, CLASSPATH_PREFIX);
			return ResourceUtil.asStream(resourceName);
		}

		try {
			// try URL
			return FileUtil.asInputStream(getFileByURL(new URL(generalPath)));
		} catch (MalformedURLException ex) {
			// no URL -> treat as file path
			return FileUtil.asInputStream(generalPath);
		}
	}

	private static File getFileByURL(URL fileUrl) throws FileNotFoundException {
		Validate.notNull(fileUrl, "Resource URL must not be null");
		if (!URL_PROTOCOL_FILE.equals(fileUrl.getProtocol())) {
			throw new FileNotFoundException("URL cannot be resolved to absolute file path "
					+ "because it does not reside in the file system: " + fileUrl);
		}
		try {
			return new File(toURI(fileUrl.toString()).getSchemeSpecificPart());
		} catch (URISyntaxException ex) {
			// Fallback for URLs that are not valid URIs (should hardly ever happen).
			return new File(fileUrl.getFile());
		}
	}

	public static URI toURI(String location) throws URISyntaxException {
		return new URI(StringUtils.replace(location, " ", "%20"));
	}
}