sviolet.thistle.util.common.CloseableUtils Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of thistle-common Show documentation
Show all versions of thistle-common Show documentation
Comprehensive Java common library (Java7+)
/*
* Copyright (C) 2015-2018 S.Violet
*
* 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.
*
* Project GitHub: https://github.com/shepherdviolet/thistle
* Email: [email protected]
*/
package sviolet.thistle.util.common;
import sviolet.thistle.entity.common.Destroyable;
import java.io.Closeable;
import java.lang.reflect.Method;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.security.AccessController;
import java.security.PrivilegedAction;
/**
* Closeable工具
*
* @author S.Violet
*/
public class CloseableUtils {
public static void closeQuiet(Closeable closeable) {
if (closeable == null) {
return;
}
try {
closeable.close();
} catch (Exception ignore) {
}
}
public static void closeQuiet(Destroyable destroyable) {
if (destroyable == null) {
return;
}
try {
destroyable.onDestroy();
} catch (Exception ignore) {
}
}
public static void closeIfCloseable(Object obj){
if (obj == null) {
return;
}
try {
if (obj instanceof Closeable){
((Closeable) obj).close();
} else if (obj instanceof Destroyable) {
((Destroyable) obj).onDestroy();
}
} catch (Exception ignore){
}
}
/************************************************************************************************************
* MappedByteBuffer:注意事项
* MappedByteBuffer在一些运行时环境中(例如HOTSPOT), 会占用内存并占用文件句柄, 导致文件无法读写删除, 直到对象被GC.
* 且没有常规办法可以回收资源. ANDROID中不存在此问题.
* isMappedByteBufferCanClean方法可以判断当前运行环境是否能手动回收MappedByteBuffer, 无法手动回收的运行时环境建
* 议不要随便使用MappedByteBuffer, 改用传统的IO.
* cleanMappedByteBuffer方法可以手动回收MappedByteBuffer.
*
* MappedByteBuffer是通过下列方法获得的:
* FileInputStream inputStream = new FileInputStream(file);
* Channel channel = inputStream.getChannel();
* MappedByteBuffer byteBuffer = channel.map(FileChannel.MapMode.READ_ONLY, 0, file.length());
*/
private static final String SUN_MISC_CLEANER = "sun.misc.Cleaner";
private static volatile int isMappedByteBufferCanClean = -1;
private static Class directByteBufferClass;
private static Method directByteBufferCleanerMethod;
private static Method cleanerCleanMethod;
/**
* 判断当前运行环境是否能手动回收MappedByteBuffer, 无法手动回收的运行时建议不要随便使用MappedByteBuffer, 改用传统的IO.
* @return true:支持手动回收MappedByteBuffer
*/
public static boolean isMappedByteBufferCanClean(){
if (isMappedByteBufferCanClean >= 0){
return isMappedByteBufferCanClean == 0;
}
//安卓平台不可用手动回收, 但是不回收也不会存在文件被锁的问题
if (PlatformUtils.PLATFORM == PlatformUtils.Platform.DALVIK){
isMappedByteBufferCanClean = 1;
return false;
}
return AccessController.doPrivileged(new PrivilegedAction() {
@Override
public Boolean run() {
try {
// JDK 11 这里要改
directByteBufferClass = Class.forName("java.nio.DirectByteBuffer");
directByteBufferCleanerMethod = directByteBufferClass.getDeclaredMethod("cleaner");
if (directByteBufferCleanerMethod == null){
throw new Exception("Method cleaner can not find in java.nio.DirectByteBuffer");
}
if (!SUN_MISC_CLEANER.equals(directByteBufferCleanerMethod.getReturnType().getName())){
throw new Exception("Return type of method cleaner is not sun.misc.Cleaner");
}
directByteBufferCleanerMethod.setAccessible(true);
Class cleanerClass = Class.forName("sun.misc.Cleaner");
cleanerCleanMethod = cleanerClass.getDeclaredMethod("clean");
if (cleanerCleanMethod == null){
throw new Exception("Method clean can not find in sun.misc.Cleaner");
}
cleanerCleanMethod.setAccessible(true);
isMappedByteBufferCanClean = 0;
return true;
} catch (Throwable t) {
// new Exception("WARNING:This jre environment can not clean MappedByteBuffer manually(1), isMappedByteBufferCanClean = false", t).printStackTrace();
System.out.println("WARNING:This jre environment can not clean MappedByteBuffer manually(1), isMappedByteBufferCanClean = false");
isMappedByteBufferCanClean = 1;
return false;
}
}
});
}
/**
* 手动回收MappedByteBuffer.
* @return true:回收成功
*/
public static boolean cleanMappedByteBuffer(final ByteBuffer byteBuffer) {
if (byteBuffer instanceof MappedByteBuffer && isMappedByteBufferCanClean()){
return AccessController.doPrivileged(new PrivilegedAction() {
@Override
public Boolean run() {
try {
if (!directByteBufferClass.isAssignableFrom(byteBuffer.getClass())){
return false;
}
cleanerCleanMethod.invoke(directByteBufferCleanerMethod.invoke(byteBuffer));
return true;
} catch (Throwable t) {
System.out.println("WARNING:This jre environment can not clean MappedByteBuffer manually(2), isMappedByteBufferCanClean = false");
isMappedByteBufferCanClean = 1;
return false;
}
}
});
} else {
return false;
}
}
}