spring Handler 源码

springboot Handler 代码

文件路径：/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/Handler.java

/*
 * Copyright 2012-2022 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
 *
 *      https://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.springframework.boot.loader.jar;

import java.io.File;
import java.io.IOException;
import java.lang.ref.SoftReference;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLStreamHandler;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.regex.Pattern;

/**
 * {@link URLStreamHandler} for Spring Boot loader {@link JarFile}s.
 *
 * @author Phillip Webb
 * @author Andy Wilkinson
 * @since 1.0.0
 * @see JarFile#registerUrlProtocolHandler()
 */
public class Handler extends URLStreamHandler {

	// NOTE: in order to be found as a URL protocol handler, this class must be public,
	// must be named Handler and must be in a package ending '.jar'

	private static final String JAR_PROTOCOL = "jar:";

	private static final String FILE_PROTOCOL = "file:";

	private static final String TOMCAT_WARFILE_PROTOCOL = "war:file:";

	private static final String SEPARATOR = "!/";

	private static final Pattern SEPARATOR_PATTERN = Pattern.compile(SEPARATOR, Pattern.LITERAL);

	private static final String CURRENT_DIR = "/./";

	private static final Pattern CURRENT_DIR_PATTERN = Pattern.compile(CURRENT_DIR, Pattern.LITERAL);

	private static final String PARENT_DIR = "/../";

	private static final String PROTOCOL_HANDLER = "java.protocol.handler.pkgs";

	private static final String[] FALLBACK_HANDLERS = { "sun.net.www.protocol.jar.Handler" };

	private static URL jarContextUrl;

	private static SoftReference<Map<File, JarFile>> rootFileCache;

	static {
		rootFileCache = new SoftReference<>(null);
	}

	private final JarFile jarFile;

	private URLStreamHandler fallbackHandler;

	public Handler() {
		this(null);
	}

	public Handler(JarFile jarFile) {
		this.jarFile = jarFile;
	}

	@Override
	protected URLConnection openConnection(URL url) throws IOException {
		if (this.jarFile != null && isUrlInJarFile(url, this.jarFile)) {
			return JarURLConnection.get(url, this.jarFile);
		}
		try {
			return JarURLConnection.get(url, getRootJarFileFromUrl(url));
		}
		catch (Exception ex) {
			return openFallbackConnection(url, ex);
		}
	}

	private boolean isUrlInJarFile(URL url, JarFile jarFile) throws MalformedURLException {
		// Try the path first to save building a new url string each time
		return url.getPath().startsWith(jarFile.getUrl().getPath())
				&& url.toString().startsWith(jarFile.getUrlString());
	}

	private URLConnection openFallbackConnection(URL url, Exception reason) throws IOException {
		try {
			URLConnection connection = openFallbackTomcatConnection(url);
			connection = (connection != null) ? connection : openFallbackContextConnection(url);
			return (connection != null) ? connection : openFallbackHandlerConnection(url);
		}
		catch (Exception ex) {
			if (reason instanceof IOException ioException) {
				log(false, "Unable to open fallback handler", ex);
				throw ioException;
			}
			log(true, "Unable to open fallback handler", ex);
			if (reason instanceof RuntimeException runtimeException) {
				throw runtimeException;
			}
			throw new IllegalStateException(reason);
		}
	}

	/**
	 * Attempt to open a Tomcat formatted 'jar:war:file:...' URL. This method allows us to
	 * use our own nested JAR support to open the content rather than the logic in
	 * {@code sun.net.www.protocol.jar.URLJarFile} which will extract the nested jar to
	 * the temp folder to that its content can be accessed.
	 * @param url the URL to open
	 * @return a {@link URLConnection} or {@code null}
	 */
	private URLConnection openFallbackTomcatConnection(URL url) {
		String file = url.getFile();
		if (isTomcatWarUrl(file)) {
			file = file.substring(TOMCAT_WARFILE_PROTOCOL.length());
			file = file.replaceFirst("\\*/", "!/");
			try {
				URLConnection connection = openConnection(new URL("jar:file:" + file));
				connection.getInputStream().close();
				return connection;
			}
			catch (IOException ex) {
			}
		}
		return null;
	}

	private boolean isTomcatWarUrl(String file) {
		if (file.startsWith(TOMCAT_WARFILE_PROTOCOL) || !file.contains("*/")) {
			try {
				URLConnection connection = new URL(file).openConnection();
				if (connection.getClass().getName().startsWith("org.apache.catalina")) {
					return true;
				}
			}
			catch (Exception ex) {
			}
		}
		return false;
	}

	/**
	 * Attempt to open a fallback connection by using a context URL captured before the
	 * jar handler was replaced with our own version. Since this method doesn't use
	 * reflection it won't trigger "illegal reflective access operation has occurred"
	 * warnings on Java 13+.
	 * @param url the URL to open
	 * @return a {@link URLConnection} or {@code null}
	 */
	private URLConnection openFallbackContextConnection(URL url) {
		try {
			if (jarContextUrl != null) {
				return new URL(jarContextUrl, url.toExternalForm()).openConnection();
			}
		}
		catch (Exception ex) {
		}
		return null;
	}

	/**
	 * Attempt to open a fallback connection by using reflection to access Java's default
	 * jar {@link URLStreamHandler}.
	 * @param url the URL to open
	 * @return the {@link URLConnection}
	 * @throws Exception if not connection could be opened
	 */
	private URLConnection openFallbackHandlerConnection(URL url) throws Exception {
		URLStreamHandler fallbackHandler = getFallbackHandler();
		return new URL(null, url.toExternalForm(), fallbackHandler).openConnection();
	}

	private URLStreamHandler getFallbackHandler() {
		if (this.fallbackHandler != null) {
			return this.fallbackHandler;
		}
		for (String handlerClassName : FALLBACK_HANDLERS) {
			try {
				Class<?> handlerClass = Class.forName(handlerClassName);
				this.fallbackHandler = (URLStreamHandler) handlerClass.getDeclaredConstructor().newInstance();
				return this.fallbackHandler;
			}
			catch (Exception ex) {
				// Ignore
			}
		}
		throw new IllegalStateException("Unable to find fallback handler");
	}

	private void log(boolean warning, String message, Exception cause) {
		try {
			Level level = warning ? Level.WARNING : Level.FINEST;
			Logger.getLogger(getClass().getName()).log(level, message, cause);
		}
		catch (Exception ex) {
			if (warning) {
				System.err.println("WARNING: " + message);
			}
		}
	}

	@Override
	protected void parseURL(URL context, String spec, int start, int limit) {
		if (spec.regionMatches(true, 0, JAR_PROTOCOL, 0, JAR_PROTOCOL.length())) {
			setFile(context, getFileFromSpec(spec.substring(start, limit)));
		}
		else {
			setFile(context, getFileFromContext(context, spec.substring(start, limit)));
		}
	}

	private String getFileFromSpec(String spec) {
		int separatorIndex = spec.lastIndexOf("!/");
		if (separatorIndex == -1) {
			throw new IllegalArgumentException("No !/ in spec '" + spec + "'");
		}
		try {
			new URL(spec.substring(0, separatorIndex));
			return spec;
		}
		catch (MalformedURLException ex) {
			throw new IllegalArgumentException("Invalid spec URL '" + spec + "'", ex);
		}
	}

	private String getFileFromContext(URL context, String spec) {
		String file = context.getFile();
		if (spec.startsWith("/")) {
			return trimToJarRoot(file) + SEPARATOR + spec.substring(1);
		}
		if (file.endsWith("/")) {
			return file + spec;
		}
		int lastSlashIndex = file.lastIndexOf('/');
		if (lastSlashIndex == -1) {
			throw new IllegalArgumentException("No / found in context URL's file '" + file + "'");
		}
		return file.substring(0, lastSlashIndex + 1) + spec;
	}

	private String trimToJarRoot(String file) {
		int lastSeparatorIndex = file.lastIndexOf(SEPARATOR);
		if (lastSeparatorIndex == -1) {
			throw new IllegalArgumentException("No !/ found in context URL's file '" + file + "'");
		}
		return file.substring(0, lastSeparatorIndex);
	}

	private void setFile(URL context, String file) {
		String path = normalize(file);
		String query = null;
		int queryIndex = path.lastIndexOf('?');
		if (queryIndex != -1) {
			query = path.substring(queryIndex + 1);
			path = path.substring(0, queryIndex);
		}
		setURL(context, JAR_PROTOCOL, null, -1, null, null, path, query, context.getRef());
	}

	private String normalize(String file) {
		if (!file.contains(CURRENT_DIR) && !file.contains(PARENT_DIR)) {
			return file;
		}
		int afterLastSeparatorIndex = file.lastIndexOf(SEPARATOR) + SEPARATOR.length();
		String afterSeparator = file.substring(afterLastSeparatorIndex);
		afterSeparator = replaceParentDir(afterSeparator);
		afterSeparator = replaceCurrentDir(afterSeparator);
		return file.substring(0, afterLastSeparatorIndex) + afterSeparator;
	}

	private String replaceParentDir(String file) {
		int parentDirIndex;
		while ((parentDirIndex = file.indexOf(PARENT_DIR)) >= 0) {
			int precedingSlashIndex = file.lastIndexOf('/', parentDirIndex - 1);
			if (precedingSlashIndex >= 0) {
				file = file.substring(0, precedingSlashIndex) + file.substring(parentDirIndex + 3);
			}
			else {
				file = file.substring(parentDirIndex + 4);
			}
		}
		return file;
	}

	private String replaceCurrentDir(String file) {
		return CURRENT_DIR_PATTERN.matcher(file).replaceAll("/");
	}

	@Override
	protected int hashCode(URL u) {
		return hashCode(u.getProtocol(), u.getFile());
	}

	private int hashCode(String protocol, String file) {
		int result = (protocol != null) ? protocol.hashCode() : 0;
		int separatorIndex = file.indexOf(SEPARATOR);
		if (separatorIndex == -1) {
			return result + file.hashCode();
		}
		String source = file.substring(0, separatorIndex);
		String entry = canonicalize(file.substring(separatorIndex + 2));
		try {
			result += new URL(source).hashCode();
		}
		catch (MalformedURLException ex) {
			result += source.hashCode();
		}
		result += entry.hashCode();
		return result;
	}

	@Override
	protected boolean sameFile(URL u1, URL u2) {
		if (!u1.getProtocol().equals("jar") || !u2.getProtocol().equals("jar")) {
			return false;
		}
		int separator1 = u1.getFile().indexOf(SEPARATOR);
		int separator2 = u2.getFile().indexOf(SEPARATOR);
		if (separator1 == -1 || separator2 == -1) {
			return super.sameFile(u1, u2);
		}
		String nested1 = u1.getFile().substring(separator1 + SEPARATOR.length());
		String nested2 = u2.getFile().substring(separator2 + SEPARATOR.length());
		if (!nested1.equals(nested2)) {
			String canonical1 = canonicalize(nested1);
			String canonical2 = canonicalize(nested2);
			if (!canonical1.equals(canonical2)) {
				return false;
			}
		}
		String root1 = u1.getFile().substring(0, separator1);
		String root2 = u2.getFile().substring(0, separator2);
		try {
			return super.sameFile(new URL(root1), new URL(root2));
		}
		catch (MalformedURLException ex) {
			// Continue
		}
		return super.sameFile(u1, u2);
	}

	private String canonicalize(String path) {
		return SEPARATOR_PATTERN.matcher(path).replaceAll("/");
	}

	public JarFile getRootJarFileFromUrl(URL url) throws IOException {
		String spec = url.getFile();
		int separatorIndex = spec.indexOf(SEPARATOR);
		if (separatorIndex == -1) {
			throw new MalformedURLException("Jar URL does not contain !/ separator");
		}
		String name = spec.substring(0, separatorIndex);
		return getRootJarFile(name);
	}

	private JarFile getRootJarFile(String name) throws IOException {
		try {
			if (!name.startsWith(FILE_PROTOCOL)) {
				throw new IllegalStateException("Not a file URL");
			}
			File file = new File(URI.create(name));
			Map<File, JarFile> cache = rootFileCache.get();
			JarFile result = (cache != null) ? cache.get(file) : null;
			if (result == null) {
				result = new JarFile(file);
				addToRootFileCache(file, result);
			}
			return result;
		}
		catch (Exception ex) {
			throw new IOException("Unable to open root Jar file '" + name + "'", ex);
		}
	}

	/**
	 * Add the given {@link JarFile} to the root file cache.
	 * @param sourceFile the source file to add
	 * @param jarFile the jar file.
	 */
	static void addToRootFileCache(File sourceFile, JarFile jarFile) {
		Map<File, JarFile> cache = rootFileCache.get();
		if (cache == null) {
			cache = new ConcurrentHashMap<>();
			rootFileCache = new SoftReference<>(cache);
		}
		cache.put(sourceFile, jarFile);
	}

	/**
	 * If possible, capture a URL that is configured with the original jar handler so that
	 * we can use it as a fallback context later. We can only do this if we know that we
	 * can reset the handlers after.
	 */
	static void captureJarContextUrl() {
		if (canResetCachedUrlHandlers()) {
			String handlers = System.getProperty(PROTOCOL_HANDLER);
			try {
				System.clearProperty(PROTOCOL_HANDLER);
				try {
					resetCachedUrlHandlers();
					jarContextUrl = new URL("jar:file:context.jar!/");
					URLConnection connection = jarContextUrl.openConnection();
					if (connection instanceof JarURLConnection) {
						jarContextUrl = null;
					}
				}
				catch (Exception ex) {
				}
			}
			finally {
				if (handlers == null) {
					System.clearProperty(PROTOCOL_HANDLER);
				}
				else {
					System.setProperty(PROTOCOL_HANDLER, handlers);
				}
			}
			resetCachedUrlHandlers();
		}
	}

	private static boolean canResetCachedUrlHandlers() {
		try {
			resetCachedUrlHandlers();
			return true;
		}
		catch (Error ex) {
			return false;
		}
	}

	private static void resetCachedUrlHandlers() {
		URL.setURLStreamHandlerFactory(null);
	}

	/**
	 * Set if a generic static exception can be thrown when a URL cannot be connected.
	 * This optimization is used during class loading to save creating lots of exceptions
	 * which are then swallowed.
	 * @param useFastConnectionExceptions if fast connection exceptions can be used.
	 */
	public static void setUseFastConnectionExceptions(boolean useFastConnectionExceptions) {
		JarURLConnection.setUseFastExceptions(useFastConnectionExceptions);
	}

}

相关信息

spring 源码目录

相关文章

spring AbstractJarFile 源码

spring AsciiBytes 源码

spring Bytes 源码

spring CentralDirectoryEndRecord 源码

spring CentralDirectoryFileHeader 源码

spring CentralDirectoryParser 源码

spring CentralDirectoryVisitor 源码

spring FileHeader 源码

spring JarEntry 源码

spring JarEntryCertification 源码