org.apache.commons.io.Java7Support Maven / Gradle / Ivy
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The Apache Commons IO library contains utility classes, stream implementations, file filters,
file comparators, endian transformation classes, and much more.
package org.apache.commons.io;
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/
import java.io.File;
import java.io.IOException;
import java.lang.reflect.Array;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
/**
* Java7 feature detection and reflection based feature access.
*
* Taken from maven-shared-utils, only for private usage until we go full java7
*/
class Java7Support {
private static final boolean IS_JAVA7;
private static Method isSymbolicLink;
private static Method delete;
private static Method toPath;
private static Method exists;
private static Method toFile;
private static Method readSymlink;
private static Method createSymlink;
private static Object emptyLinkOpts;
private static Object emptyFileAttributes;
static {
boolean isJava7x = true;
try {
ClassLoader cl = Thread.currentThread().getContextClassLoader();
Class files = cl.loadClass("java.nio.file.Files");
Class path = cl.loadClass("java.nio.file.Path");
Class fa = cl.loadClass("java.nio.file.attribute.FileAttribute");
Class linkOption = cl.loadClass("java.nio.file.LinkOption");
isSymbolicLink = files.getMethod("isSymbolicLink", path);
delete = files.getMethod("delete", path);
readSymlink = files.getMethod("readSymbolicLink", path);
emptyFileAttributes = Array.newInstance(fa, 0);
createSymlink = files.getMethod("createSymbolicLink", path, path, emptyFileAttributes.getClass());
emptyLinkOpts = Array.newInstance(linkOption, 0);
exists = files.getMethod("exists", path, emptyLinkOpts.getClass());
toPath = File.class.getMethod("toPath");
toFile = path.getMethod("toFile");
} catch (ClassNotFoundException e) {
isJava7x = false;
} catch (NoSuchMethodException e) {
isJava7x = false;
}
IS_JAVA7 = isJava7x;
}
/**
* Invokes java7 isSymbolicLink
* @param file The file to check
* @return true if the file is a symbolic link
*/
public static boolean isSymLink(File file) {
try {
Object path = toPath.invoke(file);
Boolean result = (Boolean) isSymbolicLink.invoke(null, path);
return result.booleanValue();
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* Reads the target of a symbolic link
* @param symlink The symlink to read
* @return The location the symlink is pointing to
* @throws IOException Upon failure
*/
public static File readSymbolicLink(File symlink)
throws IOException {
try {
Object path = toPath.invoke(symlink);
Object resultPath = readSymlink.invoke(null, path);
return (File) toFile.invoke(resultPath);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* Indicates if a symlunk target exists
* @param file The symlink file
* @return true if the target exists
* @throws IOException upon error
*/
private static boolean exists(File file)
throws IOException {
try {
Object path = toPath.invoke(file);
final Boolean result = (Boolean) exists.invoke(null, path, emptyLinkOpts);
return result.booleanValue();
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw (RuntimeException) e.getTargetException();
}
}
/**
* Creates a symbolic link
* @param symlink The symlink to create
* @param target Where it should point
* @return The newly created symlink
* @throws IOException upon error
*/
public static File createSymbolicLink(File symlink, File target)
throws IOException {
try {
if (!exists(symlink)) {
Object link = toPath.invoke(symlink);
Object path = createSymlink.invoke(null, link, toPath.invoke(target), emptyFileAttributes);
return (File) toFile.invoke(path);
}
return symlink;
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
final Throwable targetException = e.getTargetException();
throw (IOException) targetException;
}
}
/**
* Performs a nio delete
*
* @param file the file to delete
* @throws IOException Upon error
*/
public static void delete(File file)
throws IOException {
try {
Object path = toPath.invoke(file);
delete.invoke(null, path);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw (IOException) e.getTargetException();
}
}
/**
* Indicates if the current vm has java7 lubrary support
* @return true if java7 library support
*/
public static boolean isAtLeastJava7() {
return IS_JAVA7;
}
}