fix: handle nested jar class path fallback

Fixes apolloconfig/apollo#5592

Author: nobodyiam

apollo-core/src/main/java/com/ctrip/framework/apollo/core/utils/ClassLoaderUtil.java

@@ -17,12 +17,10 @@
 package com.ctrip.framework.apollo.core.utils;
 
 import com.google.common.base.Strings;
-
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-
 import java.net.URL;
-import java.net.URLDecoder;
+import java.nio.file.Paths;
 
 /**
  * @author Jason Song(song_s@ctrip.com)
@@ -39,20 +37,11 @@ public class ClassLoaderUtil {
       loader = ClassLoader.getSystemClassLoader();
     }
 
+    String defaultClassPath = System.getProperty("user.dir");
     try {
-      URL url = loader.getResource("");
-      // get class path
-      if (url != null) {
-        classPath = url.getPath();
-        classPath = URLDecoder.decode(classPath, "utf-8");
-      }
-
-      // 如果是jar包内的，则返回当前路径
-      if (Strings.isNullOrEmpty(classPath) || classPath.contains(".jar!")) {
-        classPath = System.getProperty("user.dir");
-      }
+      classPath = resolveClassPath(loader, defaultClassPath);
     } catch (Throwable ex) {
-      classPath = System.getProperty("user.dir");
+      classPath = defaultClassPath;
       logger.warn("Failed to locate class path, fallback to user.dir: {}", classPath, ex);
     }
   }
@@ -65,6 +54,19 @@ public static String getClassPath() {
     return classPath;
   }
 
+  static String resolveClassPath(ClassLoader classLoader, String defaultClassPath) throws Exception {
+    URL url = classLoader.getResource("");
+    if (url == null || !"file".equalsIgnoreCase(url.getProtocol())) {
+      return defaultClassPath;
+    }
+
+    String resolvedClassPath = Paths.get(url.toURI()).toString();
+    if (Strings.isNullOrEmpty(resolvedClassPath)) {
+      return defaultClassPath;
+    }
+    return resolvedClassPath;
+  }
+
   public static boolean isClassPresent(String className) {
     try {
       Class.forName(className);

apollo-core/src/test/java/com/ctrip/framework/apollo/core/utils/ClassLoaderUtilTest.java

@@ -18,15 +18,42 @@
 
 import static org.junit.Assert.*;
 
+import java.net.URL;
+import java.net.URLConnection;
+import java.net.URLStreamHandler;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import org.junit.Test;
 
 public class ClassLoaderUtilTest {
   private static boolean shouldFailInInitialization = false;
+
   @Test
   public void testGetClassLoader() {
     assertNotNull(ClassLoaderUtil.getLoader());
   }
 
+  @Test
+  public void testResolveClassPathWithFileUrl() throws Exception {
+    Path tempDir = Files.createTempDirectory("apollo class path");
+    try {
+      ClassLoader classLoader = classLoaderReturning(tempDir.toUri().toURL());
+
+      assertEquals(tempDir.toString(), ClassLoaderUtil.resolveClassPath(classLoader, "fallback"));
+    } finally {
+      Files.deleteIfExists(tempDir);
+    }
+  }
+
+  @Test
+  public void testResolveClassPathFallsBackForNestedJarUrl() throws Exception {
+    String fallback = "/tmp/fallback";
+    URL nestedJarUrl = createUrl("jar:nested:/tmp/apollo-app.jar/!BOOT-INF/classes/!/");
+    ClassLoader classLoader = classLoaderReturning(nestedJarUrl);
+
+    assertEquals(fallback, ClassLoaderUtil.resolveClassPath(classLoader, fallback));
+  }
+
   @Test
   public void testIsClassPresent() {
     assertTrue(ClassLoaderUtil.isClassPresent("java.lang.String"));
@@ -50,4 +77,22 @@ public static class ClassWithInitializationError {
       }
     }
   }
-}
+
+  private ClassLoader classLoaderReturning(URL resource) {
+    return new ClassLoader(null) {
+      @Override
+      public URL getResource(String name) {
+        return resource;
+      }
+    };
+  }
+
+  private URL createUrl(String spec) throws Exception {
+    return new URL(null, spec, new URLStreamHandler() {
+      @Override
+      protected URLConnection openConnection(URL url) {
+        throw new UnsupportedOperationException();
+      }
+    });
+  }
+}