Allow JarURLConnection to be created with a relative URL

Previously, JarURLConnection assumed that that URL with which it was
created would contain the absolute path of the underlying jar file.
This meant that when it was created with a relative URL, it could fail
to find an entry or throw a StringIndexOutOfBoundsException.

This commit updates the logic for normalizing the input URL so that
both absolute and relative URLs are supported.

Closes gh-6109

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

@@ -17,17 +17,18 @@
 package org.springframework.boot.loader.jar;
 
 import java.io.ByteArrayOutputStream;
+import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.FilePermission;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.UnsupportedEncodingException;
 import java.net.MalformedURLException;
+import java.net.URI;
 import java.net.URL;
 import java.net.URLConnection;
 import java.net.URLEncoder;
 import java.net.URLStreamHandler;
-
 import java.security.Permission;
 
 /**
@@ -62,8 +63,6 @@ class JarURLConnection extends java.net.JarURLConnection {
 
 	private static final JarEntryName EMPTY_JAR_ENTRY_NAME = new JarEntryName("");
 
-	private static final String FILE_COLON_DOUBLE_SLASH = "file://";
-
 	private static final String READ_ACTION = "read";
 
 	private static ThreadLocal<Boolean> useFastExceptions = new ThreadLocal<Boolean>();
@@ -82,7 +81,7 @@ class JarURLConnection extends java.net.JarURLConnection {
 		// What we pass to super is ultimately ignored
 		super(EMPTY_JAR_URL);
 		this.url = url;
-		String spec = getNormalizedFile(url)
+		String spec = getNormalizedFileUrl(url)
 				.substring(jarFile.getUrl().getFile().length());
 		int separator;
 		while ((separator = spec.indexOf(SEPARATOR)) > 0) {
@@ -95,11 +94,10 @@ class JarURLConnection extends java.net.JarURLConnection {
 				READ_ACTION);
 	}
 
-	private String getNormalizedFile(URL url) {
-		if (!url.getFile().startsWith(FILE_COLON_DOUBLE_SLASH)) {
-			return url.getFile();
-		}
-		return "file:" + url.getFile().substring(FILE_COLON_DOUBLE_SLASH.length());
+	private String getNormalizedFileUrl(URL url) {
+		String fileName = url.getFile();
+		return new File(URI.create(fileName).getSchemeSpecificPart()).getAbsoluteFile()
+				.toURI().toString() + (fileName.endsWith("/") ? "/" : "");
 	}
 
 	private JarFile getNestedJarFile(JarFile jarFile, String name) throws IOException {

spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/jar/JarURLConnectionTests.java

@@ -0,0 +1,107 @@
+/*
+ * Copyright 2012-2016 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.springframework.boot.loader.jar;
+
+import java.io.ByteArrayInputStream;
+import java.io.File;
+import java.net.URL;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import org.springframework.boot.loader.TestJarCreator;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link JarURLConnection}.
+ *
+ * @author Andy Wilkinson
+ */
+public class JarURLConnectionTests {
+
+	@Rule
+	public TemporaryFolder temporaryFolder = new TemporaryFolder(new File("target"));
+
+	private File rootJarFile;
+
+	private JarFile jarFile;
+
+	@Before
+	public void setup() throws Exception {
+		this.rootJarFile = this.temporaryFolder.newFile();
+		TestJarCreator.createTestJar(this.rootJarFile);
+		this.jarFile = new JarFile(this.rootJarFile);
+	}
+
+	@Test
+	public void connectionToRootUsingAbsoluteUrl() throws Exception {
+		URL absoluteUrl = new URL(
+				"jar:file:" + this.rootJarFile.getAbsoluteFile() + "!/");
+		assertThat(new JarURLConnection(absoluteUrl, this.jarFile).getContent())
+				.isSameAs(this.jarFile);
+	}
+
+	@Test
+	public void connectionToRootUsingRelativeUrl() throws Exception {
+		URL relativeUrl = new URL("jar:file:" + this.rootJarFile + "!/");
+		assertThat(new JarURLConnection(relativeUrl, this.jarFile).getContent())
+				.isSameAs(this.jarFile);
+	}
+
+	@Test
+	public void connectionToEntryUsingAbsoluteUrl() throws Exception {
+		URL absoluteUrl = new URL(
+				"jar:file:" + this.rootJarFile.getAbsoluteFile() + "!/1.dat");
+		assertThat(new JarURLConnection(absoluteUrl, this.jarFile).getInputStream())
+				.hasSameContentAs(new ByteArrayInputStream(new byte[] { 1 }));
+	}
+
+	@Test
+	public void connectionToEntryUsingRelativeUrl() throws Exception {
+		URL relativeUrl = new URL("jar:file:" + this.rootJarFile + "!/1.dat");
+		assertThat(new JarURLConnection(relativeUrl, this.jarFile).getInputStream())
+				.hasSameContentAs(new ByteArrayInputStream(new byte[] { 1 }));
+	}
+
+	@Test
+	public void connectionToEntryUsingAbsoluteUrlWithFileColonSlashSlashPrefix()
+			throws Exception {
+		URL absoluteUrl = new URL(
+				"jar:file:/" + this.rootJarFile.getAbsoluteFile() + "!/1.dat");
+		assertThat(new JarURLConnection(absoluteUrl, this.jarFile).getInputStream())
+				.hasSameContentAs(new ByteArrayInputStream(new byte[] { 1 }));
+	}
+
+	@Test
+	public void connectionToEntryUsingAbsoluteUrlForNestedEntry() throws Exception {
+		URL absoluteUrl = new URL(
+				"jar:file:" + this.rootJarFile.getAbsoluteFile() + "!/nested.jar!/3.dat");
+		assertThat(new JarURLConnection(absoluteUrl, this.jarFile).getInputStream())
+				.hasSameContentAs(new ByteArrayInputStream(new byte[] { 3 }));
+	}
+
+	@Test
+	public void connectionToEntryUsingRelativeUrlForNestedEntry() throws Exception {
+		URL relativeUrl = new URL("jar:file:" + this.rootJarFile + "!/nested.jar!/3.dat");
+		assertThat(new JarURLConnection(relativeUrl, this.jarFile).getInputStream())
+				.hasSameContentAs(new ByteArrayInputStream(new byte[] { 3 }));
+	}
+
+}