com.tencent.angel.utils.NativeUtils Maven / Gradle / Ivy
/*
* Tencent is pleased to support the open source community by making Angel available.
*
* Copyright (C) 2017-2018 THL A29 Limited, a Tencent company. All rights reserved.
*
* 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
*
* https://opensource.org/licenses/Apache-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.tencent.angel.utils;
import java.io.*;
/**
* A simple library class which helps with loading dynamic libraries stored in the JAR archive.
* These libraries usualy contain implementation of some methods in native code (using JNI - Java
* Native Interface).
*/
public class NativeUtils {
/**
* Private constructor - this class will never be instanced
*/
private NativeUtils() {
}
/**
* Loads library from current JAR archive
*
* The file from JAR is copied into system temporary directory and then loaded. The temporary file
* is deleted after exiting. Method uses String as filename because the pathname is "abstract",
* not system-dependent.
*
* @param path The path of file inside JAR as absolute path (beginning with '/'), e.g.
* /package/File.ext
* @throws IOException If temporary file creation or read/write operation fails
* @throws IllegalArgumentException If source file (param path) does not exist
* @throws IllegalArgumentException If the path is not absolute or if the filename is shorter than
* three characters (restriction of {@see File#createTempFile(java.lang.String, *java.lang.String)}).
*/
public static void loadLibraryFromJar(String path) throws IOException {
if (!path.startsWith("/")) {
throw new IllegalArgumentException("The path has to be absolute (start with '/').");
}
// Obtain filename from path
String[] parts = path.split("/");
String filename = (parts.length > 1) ? parts[parts.length - 1] : null;
// Split filename to prexif and suffix (extension)
String prefix = "";
String suffix = null;
if (filename != null) {
parts = filename.split("\\.", 2);
prefix = parts[0];
suffix = (parts.length > 1) ? "." + parts[parts.length - 1] : null; // Thanks, davs! :-)
}
// Check if the filename is okay
if (filename == null || prefix.length() < 3) {
throw new IllegalArgumentException("The filename has to be at least 3 characters long.");
}
// Prepare temporary file
File temp = File.createTempFile(prefix, suffix);
temp.deleteOnExit();
System.out.println("Temp file for native so file is " + temp.getAbsolutePath());
if (!temp.exists()) {
throw new FileNotFoundException("File " + temp.getAbsolutePath() + " does not exist.");
}
// Prepare buffer for data copying
byte[] buffer = new byte[1024];
int readBytes;
// Open and check input stream
InputStream is = NativeUtils.class.getResourceAsStream(path);
if (is == null) {
throw new FileNotFoundException("File " + path + " was not found inside JAR.");
}
// Open output stream and copy data between source file in JAR and the temporary file
OutputStream os = new FileOutputStream(temp);
try {
while ((readBytes = is.read(buffer)) != -1) {
os.write(buffer, 0, readBytes);
}
} finally {
// If read/write fails, close streams safely before throwing an exception
os.close();
is.close();
}
// Finally, load the library
System.load(temp.getAbsolutePath());
}
}