Spring Boot 访问Resource路径下的文件

使用jodd包中的工具类
` package jodd.util;

import jodd.io.IOUtil;

import java.io.IOException; import java.io.InputStream; import java.net.URL; import java.net.URLConnection;

public class ResourcesUtil {

// ---------------------------------------------------------------- get resource

/**
 * Retrieves given resource as URL.
 * @see #getResourceUrl(String, ClassLoader)
 */
public static URL getResourceUrl(final String resourceName) {
	return getResourceUrl(resourceName, null);
}

/**
 * Retrieves given resource as URL. Resource is always absolute and may
 * starts with a slash character.
 * <p>
 * Resource will be loaded using class loaders in the following order:
 * <ul>
 * <li>{@link Thread#getContextClassLoader() Thread.currentThread().getContextClassLoader()}</li>
 * <li>{@link Class#getClassLoader() ClassLoaderUtil.class.getClassLoader()}</li>
 * <li>if <code>callingClass</code> is provided: {@link Class#getClassLoader() callingClass.getClassLoader()}</li>
 * </ul>
 */
public static URL getResourceUrl(String resourceName, final ClassLoader classLoader) {

	if (resourceName.startsWith("/")) {
		resourceName = resourceName.substring(1);
	}

	URL resourceUrl;

	// try #1 - using provided class loader
	if (classLoader != null) {
		resourceUrl = classLoader.getResource(resourceName);
		if (resourceUrl != null) {
			return resourceUrl;
		}
	}

	// try #2 - using thread class loader
	final ClassLoader currentThreadClassLoader = Thread.currentThread().getContextClassLoader();
	if ((currentThreadClassLoader != null) && (currentThreadClassLoader != classLoader)) {
		resourceUrl = currentThreadClassLoader.getResource(resourceName);
		if (resourceUrl != null) {
			return resourceUrl;
		}
	}

	// try #3 - using caller classloader, similar as Class.forName()
	final Class callerClass = ClassUtil.getCallerClass(2);
	final ClassLoader callerClassLoader = callerClass.getClassLoader();

	if ((callerClassLoader != classLoader) && (callerClassLoader != currentThreadClassLoader)) {
		resourceUrl = callerClassLoader.getResource(resourceName);
		if (resourceUrl != null) {
			return resourceUrl;
		}
	}

	return null;
}

// ---------------------------------------------------------------- get resource string

public static String getResourceAsString(final String resourceName) throws IOException {
	final InputStream inputStream = getResourceAsStream(resourceName);
	try {
		final char[] data = IOUtil.readChars(inputStream);
		return new String(data);
	}
	finally {
		IOUtil.close(inputStream);
	}
}

// ---------------------------------------------------------------- get resource stream

/**
 * Opens a resource of the specified name for reading.
 * @see #getResourceAsStream(String, ClassLoader)
 */
public static InputStream getResourceAsStream(final String resourceName) throws IOException {
	return getResourceAsStream(resourceName, null);
}

/**
 * Opens a resource of the specified name for reading.
 * @see #getResourceUrl(String, ClassLoader)
 */
public static InputStream getResourceAsStream(final String resourceName, final ClassLoader callingClass) throws IOException {
	final URL url = getResourceUrl(resourceName, callingClass);
	if (url != null) {
		return url.openStream();
	}
	return null;
}

/**
 * Opens a resource of the specified name for reading. Controls caching,
 * that is important when the same jar is reloaded using custom classloader.
 */
public static InputStream getResourceAsStream(final String resourceName, final ClassLoader callingClass, final boolean useCache) throws IOException {
	final URL url = getResourceUrl(resourceName, callingClass);
	if (url != null) {
		final URLConnection urlConnection = url.openConnection();
		urlConnection.setUseCaches(useCache);
		return urlConnection.getInputStream();
	}
	return null;
}

} `