Fix URL from String creation to work on Windows

Fixed the nested jar URLHandler to correctly deal with files on
Windows.

Fixes gh-269

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/Handler.java

@@ -34,6 +34,8 @@ public class Handler extends URLStreamHandler {
 	// NOTE: in order to be found as a URL protocol hander, this class must be public,
 	// must be named Handler and must be in a package ending '.jar'
 
+	private static final String FILE_PROTOCOL = "file:";
+
 	private static final String SEPARATOR = JarURLConnection.SEPARATOR;
 
 	private final JarFile jarFile;
@@ -74,7 +76,11 @@ public class Handler extends URLStreamHandler {
 
 	private JarFile getRootJarFile(String name) throws IOException {
 		try {
-			return new JarFile(new File(new URL(name).toURI()));
+			if (!name.startsWith(FILE_PROTOCOL)) {
+				throw new IllegalStateException("Not a file URL");
+			}
+			String path = name.substring(FILE_PROTOCOL.length());
+			return new JarFile(new File(path));
 		}
 		catch (Exception ex) {
 			throw new IOException("Unable to open root Jar file '" + name + "'", ex);

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFile.java

@@ -104,7 +104,7 @@ public class JarFile extends java.util.jar.JarFile implements Iterable<JarEntryD
 	 * @throws IOException
 	 */
 	JarFile(RandomAccessDataFile file, JarEntryFilter... filters) throws IOException {
-		this(file, file.getFile().getPath(), file, filters);
+		this(file, file.getFile().getAbsolutePath(), file, filters);
 	}
 
 	/**