example app for gh-8822

gh-8822/build.gradle

@@ -0,0 +1,42 @@
+apply plugin: 'org.springframework.boot'
+
+buildscript {
+    ext {
+        springBootVersion = '1.5.2.RELEASE'
+    }
+    repositories {
+        jcenter()
+    }
+    dependencies {
+        // http://mvnrepository.com/artifact/org.springframework.boot/spring-boot-gradle-plugin
+        classpath group: 'org.springframework.boot', name: 'spring-boot-gradle-plugin', version: springBootVersion
+    }
+}
+
+wrapper {
+    gradleVersion = '3.4.1'
+    distributionType = Wrapper.DistributionType.ALL
+}
+
+repositories.addAll rootProject.buildscript.repositories
+
+subprojects {
+    repositories.addAll rootProject.buildscript.repositories
+    buildscript.repositories.addAll rootProject.buildscript.repositories
+}
+
+dependencies {
+    // https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-loader
+    // should be runtime but JavaDoc @see requires compile for validation
+    compile group: 'org.springframework.boot', name: 'spring-boot-loader', version: springBootVersion
+}
+
+bootRepackage {
+    // https://github.com/spring-projects/spring-boot/issues/1113
+    // https://github.com/spring-projects/spring-boot/issues/8167
+    classifier = 'repack'
+}
+
+jar {
+    manifest.attributes 'Main-Class': 'Main'
+}

gh-8822/src/main/java/Main.java

@@ -0,0 +1,94 @@
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.nio.file.FileSystems;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Collections;
+
+/**
+ * @see org.springframework.boot.loader.JarLauncher#main(java.lang.String[])
+ * @see org.springframework.boot.loader.Launcher#launch(java.lang.String[])
+ * @see org.springframework.boot.loader.ExecutableArchiveLauncher#getClassPathArchives()
+ * @see org.springframework.boot.loader.archive.JarFileArchive#getNestedArchives(org.springframework.boot.loader.archive.Archive.EntryFilter)
+ * @see org.springframework.boot.loader.archive.JarFileArchive#getNestedArchive(org.springframework.boot.loader.archive.Archive.Entry)
+ * @see org.springframework.boot.loader.jar.JarFile#getNestedJarFile(java.util.zip.ZipEntry)
+ * @see org.springframework.boot.loader.jar.JarFile#getNestedJarFile(org.springframework.boot.loader.jar.JarEntry)
+ * @see org.springframework.boot.loader.jar.JarFile#createJarFileFromEntry(org.springframework.boot.loader.jar.JarEntry)
+ * @see <a href="https://github.com/spring-projects/spring-boot/issues/7096">Jar launcer adds ! after BOOT-INF/classes url for resource</a>
+ * @see <a href="https://github.com/spring-projects/spring-boot/issues/7110">org.springframework.boot.loader.LaunchedURLClassLoader unable to load 3rd party FileSystemProvider implementation from spring boot executable JAR</a>
+ */
+public class Main {
+    public static void main(String[] args) throws URISyntaxException, IOException {
+        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
+        printClassLoaderTree(classLoader);
+
+        // get resourceUri
+        URL resourceUrl = classLoader.getResource("test.txt");
+        assert resourceUrl != null;
+        URI resourceUri = resourceUrl.toURI();
+
+        // open jar if necessary
+        if (resourceUri.toString().startsWith("jar:")) {
+            System.out.println("\nOpening jar…");
+            FileSystems.newFileSystem(resourceUri, Collections.emptyMap());
+        }
+
+        System.out.println("");
+
+        // test files exists
+        {
+            Path resourcePath = Paths.get(resourceUri);
+            boolean exists = Files.exists(resourcePath);
+            System.out.println(
+                    "Files.exists(resourcePath): " + exists
+                            + "\n    resourcePath: " + resourcePath
+                            + "\n    resourceUri: " + resourceUri
+            );
+        }
+
+        // apply workaround
+        {
+            System.out.println("\nApplying workaround. Replacing '!/BOOT-INF/classes!/' with '!/BOOT-INF/classes/'.\n");
+            String brokenUri = resourceUri.toString();
+            String fixedUri = brokenUri.replace("!/BOOT-INF/classes!/", "!/BOOT-INF/classes/");
+            resourceUri = new URI(fixedUri);
+        }
+
+        // test files exists
+        {
+            Path resourcePath = Paths.get(resourceUri);
+            boolean exists = Files.exists(resourcePath);
+            System.out.println(
+                    "Files.exists(resourcePath): " + exists
+                            + "\n    resourcePath: " + resourcePath
+                            + "\n    resourceUri: " + resourceUri
+            );
+        }
+    }
+
+    private static void printClassLoaderTree(ClassLoader loader) {
+        StringBuilder message = new StringBuilder();
+
+        message.append("Using current thread context ClassLoader:\n");
+        message.append("  \u25b8");
+        message.append(loader.getClass().getCanonicalName());
+        message.append('\n');
+
+        ClassLoader curClassLoader = loader;
+        int lvl = 0;
+        while ((curClassLoader = curClassLoader.getParent()) != null) {
+            int curLvl = ++lvl;
+            message.append("   ");
+            while (curLvl-- > 1) {
+                message.append("      ");
+            }
+            message.append("   \u2514\u2500\u2574");
+            message.append(curClassLoader.getClass().getCanonicalName());
+            message.append('\n');
+        }
+        System.out.print(message);
+    }
+}