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/*
* Copyright 2015 Google Inc.
*
* 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 com.google.common.jimfs;
import static java.nio.charset.StandardCharsets.UTF_8;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import com.google.common.base.MoreObjects;
import com.google.common.collect.ImmutableList;
import java.io.IOException;
import java.lang.reflect.Method;
import java.net.URLClassLoader;
import java.nio.file.FileSystem;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.spi.FileSystemProvider;
import java.util.List;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;
/**
* Tests behavior when user code loads Jimfs in a separate class loader from the system class loader
* (which is what {@link FileSystemProvider#installedProviders()} uses to load {@link
* FileSystemProvider}s as services from the classpath).
*
* @author Colin Decker
*/
@RunWith(JUnit4.class)
public class ClassLoaderTest {
@Test
public void separateClassLoader() throws Exception {
ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
ClassLoader loader = MoreObjects.firstNonNull(contextLoader, systemLoader);
if (loader instanceof URLClassLoader) {
// Anything we can do if it isn't a URLClassLoader?
URLClassLoader urlLoader = (URLClassLoader) loader;
ClassLoader separateLoader =
new URLClassLoader(
urlLoader.getURLs(), systemLoader.getParent()); // either null or the boostrap loader
Thread.currentThread().setContextClassLoader(separateLoader);
try {
Class<?> thisClass = separateLoader.loadClass(getClass().getName());
Method createFileSystem = thisClass.getDeclaredMethod("createFileSystem");
// First, the call to Jimfs.newFileSystem in createFileSystem needs to succeed
Object fs = createFileSystem.invoke(null);
// Next, some sanity checks:
// The file system is a JimfsFileSystem
assertEquals("com.google.common.jimfs.JimfsFileSystem", fs.getClass().getName());
// But it is not seen as an instance of JimfsFileSystem here because it was loaded by a
// different ClassLoader
assertFalse(fs instanceof JimfsFileSystem);
// But it should be an instance of FileSystem regardless, which is the important thing.
assertTrue(fs instanceof FileSystem);
// And normal file operations should work on it despite its provenance from a different
// ClassLoader
writeAndRead((FileSystem) fs, "bar.txt", "blah blah");
// And for the heck of it, test the contents of the file that was created in
// createFileSystem too
assertEquals(
"blah", Files.readAllLines(((FileSystem) fs).getPath("foo.txt"), UTF_8).get(0));
} finally {
Thread.currentThread().setContextClassLoader(contextLoader);
}
}
}
/**
* This method is really just testing that {@code Jimfs.newFileSystem()} succeeds. Without special
* handling, when the system class loader loads our {@code FileSystemProvider} implementation as a
* service and this code (the user code) is loaded in a separate class loader, the system-loaded
* provider won't see the instance of {@code Configuration} we give it as being an instance of the
* {@code Configuration} it's expecting (they're completely separate classes) and creation of the
* file system will fail.
*/
public static FileSystem createFileSystem() throws IOException {
FileSystem fs = Jimfs.newFileSystem(Configuration.unix());
// Just some random operations to verify that basic things work on the created file system.
writeAndRead(fs, "foo.txt", "blah");
return fs;
}
private static void writeAndRead(FileSystem fs, String path, String text) throws IOException {
Path p = fs.getPath(path);
Files.write(p, ImmutableList.of(text), UTF_8);
List<String> lines = Files.readAllLines(p, UTF_8);
assertEquals(text, lines.get(0));
}
}
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