通过类名就知道这是一个平台有关的类，通过对该类的学习可以帮助我们实现一个跨平台的应用。但是有些方法放的实现不是很好，比如：isWindows0。通过File的separator就可以判断出来。没必要那么复杂把。 目前平台的判断是推崇能力判断，这里也是通过这样来判断是否是android的，jdk的版本。这种思想最初好像是js来判断浏览器的版本。还有就是PlatformDependent是一个对外的接口，真正的实现为PlatformDependent0类，这是一个代理模式吗
能力判断：
Class.forName("android.app.Application", false, getSystemClassLoader());上面是判断平台是否为android. 该方法用来判断该类是否存在，false表示不实例化一个Class对象。
反射作用：
JDK中有很多的类的字段或者方法是私有的，通过反射我们就可以访问这些私有的属性和方法。下面是怎么创建一个UnSafe对象的代码
Field unsafeField = Unsafe.class.getDeclaredField("theUnsafe");
unsafeField.setAccessible(true);
unsafe = (Unsafe) unsafeField.get(null);Unsafe.getUnsafe()不能直接访问
Unsafe的使用
在这个类中大量使用了unsafe的功能
/*
* Copyright 2012 The Netty Project
*
* The Netty Project 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.
*/
package io.netty.util.internal; import io.netty.util.CharsetUtil;
import io.netty.util.internal.chmv8.ConcurrentHashMapV8;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory; import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.nio.ByteBuffer;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Queue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.AtomicLongFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import java.util.regex.Matcher;
import java.util.regex.Pattern; /**
*
* 用来检测运行时系统的属性的工具类，可以通过设置io.netty.noUnsafe属性禁止使用sun.misc.Unsafe对象
* System.setProperty("io.netty.allocator.type","pooled");
* System.setPropperty("io.netty.noUnsafe",false)
* -XX:MaxDirectMemorySize
*
* 该类实现实现：class加载的时候获取系统的属性保存到statuc变量中，然后访问的时候直接返回这个变量
*/
public final class PlatformDependent { private static final InternalLogger logger = InternalLoggerFactory.getInstance(PlatformDependent.class); private static final Pattern MAX_DIRECT_MEMORY_SIZE_ARG_PATTERN = Pattern.compile(
"\\s*-XX:MaxDirectMemorySize\\s*=\\s*([0-9]+)\\s*([kKmMgG]?)\\s*$"); private static final boolean IS_ANDROID = isAndroid0();
private static final boolean IS_WINDOWS = isWindows0();
private static final boolean IS_ROOT = isRoot0(); private static final int JAVA_VERSION = javaVersion0(); /**
* android不支持TCP_NODELAY这个TCP选项
*/
private static final boolean CAN_ENABLE_TCP_NODELAY_BY_DEFAULT = !isAndroid(); private static final boolean HAS_UNSAFE = hasUnsafe0();
private static final boolean CAN_USE_CHM_V8 = HAS_UNSAFE && JAVA_VERSION < 8;
private static final boolean DIRECT_BUFFER_PREFERRED =
HAS_UNSAFE && !SystemPropertyUtil.getBoolean("io.netty.noPreferDirect", false);
private static final long MAX_DIRECT_MEMORY = maxDirectMemory0(); /**
* 字节数组的基本偏移
* arrayBaseOffset方法是一个本地方法，可以获取数组第一个元素的偏移地址
* 数组是个对象，数组存储了数据和一些对象信息
*/
private static final long ARRAY_BASE_OFFSET = arrayBaseOffset0(); private static final boolean HAS_JAVASSIST = hasJavassist0(); private static final File TMPDIR = tmpdir0(); private static final int BIT_MODE = bitMode0(); private static final int ADDRESS_SIZE = addressSize0(); static {
if (logger.isDebugEnabled()) {
logger.debug("-Dio.netty.noPreferDirect: {}", !DIRECT_BUFFER_PREFERRED);
} if (!hasUnsafe() && !isAndroid()) {
logger.info(
"Your platform does not provide complete low-level API for accessing direct buffers reliably. " +
"Unless explicitly requested, heap buffer will always be preferred to avoid potential system " +
"unstability.");
}
} /**
* Returns {@code true} if and only if the current platform is Android
*/
public static boolean isAndroid() {
return IS_ANDROID;
} /**
* Return {@code true} if the JVM is running on Windows
*/
public static boolean isWindows() {
return IS_WINDOWS;
} /**
* Return {@code true} if the current user is root. Note that this method returns
* {@code false} if on Windows.
*/
public static boolean isRoot() {
return IS_ROOT;
} /**
* Return the version of Java under which this library is used.
*/
public static int javaVersion() {
return JAVA_VERSION;
} /**
* Returns {@code true} if and only if it is fine to enable TCP_NODELAY socket option by default.
*/
public static boolean canEnableTcpNoDelayByDefault() {
return CAN_ENABLE_TCP_NODELAY_BY_DEFAULT;
} /**
* 如果classpath下sun.misc.Unsafe可用，那么返回True,用来提高访问direct内存的性能
* @return
*/
public static boolean hasUnsafe() {
return HAS_UNSAFE;
} /**
* Returns {@code true} if the platform has reliable low-level direct buffer access API and a user specified
* {@code -Dio.netty.preferDirect} option.
*
* 如果用户定义了 -Dio.netty.preferDirect的参数同时可以通过api访问direct buffer
*/
public static boolean directBufferPreferred() {
return DIRECT_BUFFER_PREFERRED;
} /**
* Returns the maximum memory reserved for direct buffer allocation.
*/
public static long maxDirectMemory() {
return MAX_DIRECT_MEMORY;
} /**
* Returns {@code true} if and only if Javassist is available.
*/
public static boolean hasJavassist() {
return HAS_JAVASSIST;
} /**
* Returns the temporary directory.
*/
public static File tmpdir() {
return TMPDIR;
} /**
* Returns the bit mode of the current VM (usually 32 or 64.)
*/
public static int bitMode() {
return BIT_MODE;
} /**
* Return the address size of the OS.
* 4 (for 32 bits systems ) and 8 (for 64 bits systems).
*/
public static int addressSize() {
return ADDRESS_SIZE;
} public static long allocateMemory(long size) {
return PlatformDependent0.allocateMemory(size);
} public static void freeMemory(long address) {
PlatformDependent0.freeMemory(address);
} /**
* Raises an exception bypassing compiler checks for checked exceptions.
*/
public static void throwException(Throwable t) {
if (hasUnsafe()) {
PlatformDependent0.throwException(t);
} else {
PlatformDependent.<RuntimeException>throwException0(t);
}
} @SuppressWarnings("unchecked")
private static <E extends Throwable> void throwException0(Throwable t) throws E {
throw (E) t;
} /**
* Creates a new fastest {@link ConcurrentMap} implementaion for the current platform.
*/
public static <K, V> ConcurrentMap<K, V> newConcurrentHashMap() {
if (CAN_USE_CHM_V8) {
return new ConcurrentHashMapV8<K, V>();
} else {
return new ConcurrentHashMap<K, V>();
}
} /**
* Creates a new fastest {@link ConcurrentMap} implementaion for the current platform.
*/
public static <K, V> ConcurrentMap<K, V> newConcurrentHashMap(int initialCapacity) {
if (CAN_USE_CHM_V8) {
return new ConcurrentHashMapV8<K, V>(initialCapacity);
} else {
return new ConcurrentHashMap<K, V>(initialCapacity);
}
} /**
* Creates a new fastest {@link ConcurrentMap} implementaion for the current platform.
*/
public static <K, V> ConcurrentMap<K, V> newConcurrentHashMap(int initialCapacity, float loadFactor) {
if (CAN_USE_CHM_V8) {
return new ConcurrentHashMapV8<K, V>(initialCapacity, loadFactor);
} else {
return new ConcurrentHashMap<K, V>(initialCapacity, loadFactor);
}
} /**
* Creates a new fastest {@link ConcurrentMap} implementaion for the current platform.
*/
public static <K, V> ConcurrentMap<K, V> newConcurrentHashMap(
int initialCapacity, float loadFactor, int concurrencyLevel) {
if (CAN_USE_CHM_V8) {
return new ConcurrentHashMapV8<K, V>(initialCapacity, loadFactor, concurrencyLevel);
} else {
return new ConcurrentHashMap<K, V>(initialCapacity, loadFactor, concurrencyLevel);
}
} /**
* Creates a new fastest {@link ConcurrentMap} implementaion for the current platform.
*/
public static <K, V> ConcurrentMap<K, V> newConcurrentHashMap(Map<? extends K, ? extends V> map) {
if (CAN_USE_CHM_V8) {
return new ConcurrentHashMapV8<K, V>(map);
} else {
return new ConcurrentHashMap<K, V>(map);
}
} /**
* Try to deallocate the specified direct {@link ByteBuffer}. Please note this method does nothing if
* the current platform does not support this operation or the specified buffer is not a direct buffer.
*/
public static void freeDirectBuffer(ByteBuffer buffer) {
if (hasUnsafe() && !isAndroid()) {
// only direct to method if we are not running on android.
// See https://github.com/netty/netty/issues/2604
PlatformDependent0.freeDirectBuffer(buffer);
}
} public static long directBufferAddress(ByteBuffer buffer) {
return PlatformDependent0.directBufferAddress(buffer);
} public static Object getObject(Object object, long fieldOffset) {
return PlatformDependent0.getObject(object, fieldOffset);
} public static Object getObjectVolatile(Object object, long fieldOffset) {
return PlatformDependent0.getObjectVolatile(object, fieldOffset);
} public static int getInt(Object object, long fieldOffset) {
return PlatformDependent0.getInt(object, fieldOffset);
} public static long objectFieldOffset(Field field) {
return PlatformDependent0.objectFieldOffset(field);
} public static byte getByte(long address) {
return PlatformDependent0.getByte(address);
} public static short getShort(long address) {
return PlatformDependent0.getShort(address);
} public static int getInt(long address) {
return PlatformDependent0.getInt(address);
} public static long getLong(long address) {
return PlatformDependent0.getLong(address);
} public static void putOrderedObject(Object object, long address, Object value) {
PlatformDependent0.putOrderedObject(object, address, value);
} public static void putByte(long address, byte value) {
PlatformDependent0.putByte(address, value);
} public static void putShort(long address, short value) {
PlatformDependent0.putShort(address, value);
} public static void putInt(long address, int value) {
PlatformDependent0.putInt(address, value);
} public static void putLong(long address, long value) {
PlatformDependent0.putLong(address, value);
} public static void copyMemory(long srcAddr, long dstAddr, long length) {
PlatformDependent0.copyMemory(srcAddr, dstAddr, length);
} public static void copyMemory(byte[] src, int srcIndex, long dstAddr, long length) {
PlatformDependent0.copyMemory(src, ARRAY_BASE_OFFSET + srcIndex, null, dstAddr, length);
} public static void copyMemory(long srcAddr, byte[] dst, int dstIndex, long length) {
PlatformDependent0.copyMemory(null, srcAddr, dst, ARRAY_BASE_OFFSET + dstIndex, length);
} /**
* Create a new optimized {@link AtomicReferenceFieldUpdater} or {@code null} if it
* could not be created. Because of this the caller need to check for {@code null} and if {@code null} is returned
* use {@link AtomicReferenceFieldUpdater#newUpdater(Class, Class, String)} as fallback.
*/
public static <U, W> AtomicReferenceFieldUpdater<U, W> newAtomicReferenceFieldUpdater(
Class<U> tclass, String fieldName) {
if (hasUnsafe()) {
try {
return PlatformDependent0.newAtomicReferenceFieldUpdater(tclass, fieldName);
} catch (Throwable ignore) {
// ignore
}
}
return null;
} /**
* Create a new optimized {@link AtomicIntegerFieldUpdater} or {@code null} if it
* could not be created. Because of this the caller need to check for {@code null} and if {@code null} is returned
* use {@link AtomicIntegerFieldUpdater#newUpdater(Class, String)} as fallback.
*/
public static <T> AtomicIntegerFieldUpdater<T> newAtomicIntegerFieldUpdater(
Class<?> tclass, String fieldName) {
if (hasUnsafe()) {
try {
return PlatformDependent0.newAtomicIntegerFieldUpdater(tclass, fieldName);
} catch (Throwable ignore) {
// ignore
}
}
return null;
} /**
* Create a new optimized {@link AtomicLongFieldUpdater} or {@code null} if it
* could not be created. Because of this the caller need to check for {@code null} and if {@code null} is returned
* use {@link AtomicLongFieldUpdater#newUpdater(Class, String)} as fallback.
*/
public static <T> AtomicLongFieldUpdater<T> newAtomicLongFieldUpdater(
Class<?> tclass, String fieldName) {
if (hasUnsafe()) {
try {
return PlatformDependent0.newAtomicLongFieldUpdater(tclass, fieldName);
} catch (Throwable ignore) {
// ignore
}
}
return null;
} /**
* Create a new {@link Queue} which is safe to use for multiple producers (different threads) and a single
* consumer (one thread!).
*/
public static <T> Queue<T> newMpscQueue() {
return new MpscLinkedQueue<T>();
} /**
* Return the {@link ClassLoader} for the given {@link Class}.
*/
public static ClassLoader getClassLoader(final Class<?> clazz) {
return PlatformDependent0.getClassLoader(clazz);
} /**
* Return the context {@link ClassLoader} for the current {@link Thread}.
*/
public static ClassLoader getContextClassLoader() {
return PlatformDependent0.getContextClassLoader();
} /**
* Return the system {@link ClassLoader}.
*/
public static ClassLoader getSystemClassLoader() {
return PlatformDependent0.getSystemClassLoader();
} private static boolean isAndroid0() {
boolean android;
try {
/**
* 下面只是判断android.app.Application是否存在，而不用实例化class对象
*/
Class.forName("android.app.Application", false, getSystemClassLoader());
android = true;
} catch (Exception e) {
// Failed to load the class uniquely available in Android.
android = false;
} if (android) {
logger.debug("Platform: Android");
}
return android;
} private static boolean isWindows0() {
boolean windows = SystemPropertyUtil.get("os.name", "").toLowerCase(Locale.US).contains("win");
if (windows) {
logger.debug("Platform: Windows");
}
return windows;
} private static boolean isRoot0() {
if (isWindows()) {
return false;
} String[] ID_COMMANDS = { "/usr/bin/id", "/bin/id", "id", "/usr/xpg4/bin/id"};
Pattern UID_PATTERN = Pattern.compile("^(?:0|[1-9][0-9]*)$");
for (String idCmd: ID_COMMANDS) {
Process p = null;
BufferedReader in = null;
String uid = null;
try {
p = Runtime.getRuntime().exec(new String[] { idCmd, "-u" });
in = new BufferedReader(new InputStreamReader(p.getInputStream(), CharsetUtil.US_ASCII));
uid = in.readLine();
in.close(); for (;;) {
try {
int exitCode = p.waitFor();
if (exitCode != 0) {
uid = null;
}
break;
} catch (InterruptedException e) {
// Ignore
}
}
} catch (Exception e) {
// Failed to run the command.
uid = null;
} finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
// Ignore
}
}
if (p != null) {
try {
p.destroy();
} catch (Exception e) {
// Android sometimes triggers an ErrnoException.
}
}
} if (uid != null && UID_PATTERN.matcher(uid).matches()) {
logger.debug("UID: {}", uid);
return "0".equals(uid);
}
} logger.debug("Could not determine the current UID using /usr/bin/id; attempting to bind at privileged ports."); Pattern PERMISSION_DENIED = Pattern.compile(".*(?:denied|not.*permitted).*");
for (int i = 1023; i > 0; i --) {
ServerSocket ss = null;
try {
ss = new ServerSocket();
ss.setReuseAddress(true);
ss.bind(new InetSocketAddress(i));
if (logger.isDebugEnabled()) {
logger.debug("UID: 0 (succeded to bind at port {})", i);
}
return true;
} catch (Exception e) {
// Failed to bind.
// Check the error message so that we don't always need to bind 1023 times.
String message = e.getMessage();
if (message == null) {
message = "";
}
message = message.toLowerCase();
if (PERMISSION_DENIED.matcher(message).matches()) {
break;
}
} finally {
if (ss != null) {
try {
ss.close();
} catch (Exception e) {
// Ignore.
}
}
}
} logger.debug("UID: non-root (failed to bind at any privileged ports)");
return false;
} /**
* 通过Class.forName来检测JDK的版本6，7，8
* @return
*/
@SuppressWarnings("LoopStatementThatDoesntLoop")
private static int javaVersion0() {
int javaVersion; // Not really a loop
for (;;) {
// Android
if (isAndroid()) {
javaVersion = 6;
break;
} try {
Class.forName("java.time.Clock", false, getClassLoader(Object.class));
javaVersion = 8;
break;
} catch (Exception e) {
// Ignore
} try {
Class.forName("java.util.concurrent.LinkedTransferQueue", false, getClassLoader(BlockingQueue.class));
javaVersion = 7;
break;
} catch (Exception e) {
// Ignore
} javaVersion = 6;
break;
} if (logger.isDebugEnabled()) {
logger.debug("Java version: {}", javaVersion);
}
return javaVersion;
} /**
* 是否可以使用sun.misc.Unsafe
* @return
*/
private static boolean hasUnsafe0() {
boolean noUnsafe = SystemPropertyUtil.getBoolean("io.netty.noUnsafe", false);
logger.debug("-Dio.netty.noUnsafe: {}", noUnsafe); if (isAndroid()) {
logger.debug("sun.misc.Unsafe: unavailable (Android)");
return false;
} if (noUnsafe) {
logger.debug("sun.misc.Unsafe: unavailable (io.netty.noUnsafe)");
return false;
} // Legacy properties
boolean tryUnsafe;
if (SystemPropertyUtil.contains("io.netty.tryUnsafe")) {
tryUnsafe = SystemPropertyUtil.getBoolean("io.netty.tryUnsafe", true);
} else {
tryUnsafe = SystemPropertyUtil.getBoolean("org.jboss.netty.tryUnsafe", true);
} if (!tryUnsafe) {
logger.debug("sun.misc.Unsafe: unavailable (io.netty.tryUnsafe/org.jboss.netty.tryUnsafe)");
return false;
} try {
boolean hasUnsafe = PlatformDependent0.hasUnsafe();
logger.debug("sun.misc.Unsafe: {}", hasUnsafe ? "available" : "unavailable");
return hasUnsafe;
} catch (Throwable t) {
// Probably failed to initialize PlatformDependent0.
return false;
}
} private static long arrayBaseOffset0() {
if (!hasUnsafe()) {
return -1;
} return PlatformDependent0.arrayBaseOffset();
} /**
* 可用的最大的director memory
* @return
*/
private static long maxDirectMemory0() {
long maxDirectMemory = 0;
try {
// Try to get from sun.misc.VM.maxDirectMemory() which should be most accurate.
Class<?> vmClass = Class.forName("sun.misc.VM", true, getSystemClassLoader());
Method m = vmClass.getDeclaredMethod("maxDirectMemory");
maxDirectMemory = ((Number) m.invoke(null)).longValue();
} catch (Throwable t) {
// Ignore
} if (maxDirectMemory > 0) {
return maxDirectMemory;
} try {
// Now try to get the JVM option (-XX:MaxDirectMemorySize) and parse it.
// Note that we are using reflection because Android doesn't have these classes.
Class<?> mgmtFactoryClass = Class.forName(
"java.lang.management.ManagementFactory", true, getSystemClassLoader());
Class<?> runtimeClass = Class.forName(
"java.lang.management.RuntimeMXBean", true, getSystemClassLoader()); Object runtime = mgmtFactoryClass.getDeclaredMethod("getRuntimeMXBean").invoke(null); @SuppressWarnings("unchecked")
List<String> vmArgs = (List<String>) runtimeClass.getDeclaredMethod("getInputArguments").invoke(runtime);
for (int i = vmArgs.size() - 1; i >= 0; i --) {
Matcher m = MAX_DIRECT_MEMORY_SIZE_ARG_PATTERN.matcher(vmArgs.get(i));
if (!m.matches()) {
continue;
} maxDirectMemory = Long.parseLong(m.group(1));
switch (m.group(2).charAt(0)) {
case 'k': case 'K':
maxDirectMemory *= 1024;
break;
case 'm': case 'M':
maxDirectMemory *= 1024 * 1024;
break;
case 'g': case 'G':
maxDirectMemory *= 1024 * 1024 * 1024;
break;
}
break;
}
} catch (Throwable t) {
// Ignore
} if (maxDirectMemory <= 0) {
maxDirectMemory = Runtime.getRuntime().maxMemory();
logger.debug("maxDirectMemory: {} bytes (maybe)", maxDirectMemory);
} else {
logger.debug("maxDirectMemory: {} bytes", maxDirectMemory);
} return maxDirectMemory;
} /**
* javassist可以动态的生成类
* @return
*/
private static boolean hasJavassist0() {
if (isAndroid()) {
return false;
} boolean noJavassist = SystemPropertyUtil.getBoolean("io.netty.noJavassist", false);
logger.debug("-Dio.netty.noJavassist: {}", noJavassist); if (noJavassist) {
logger.debug("Javassist: unavailable (io.netty.noJavassist)");
return false;
} try {
JavassistTypeParameterMatcherGenerator.generate(Object.class, getClassLoader(PlatformDependent.class));
logger.debug("Javassist: available");
return true;
} catch (Throwable t) {
// Failed to generate a Javassist-based matcher.
logger.debug("Javassist: unavailable");
logger.debug(
"You don't have Javassist in your class path or you don't have enough permission " +
"to load dynamically generated classes. Please check the configuration for better performance.");
return false;
}
} /**
* 通过io.netty.tmpdir 或者 java.io.tmpdir 配置netty的临时目录
* @return
*/
private static File tmpdir0() {
File f;
try {
f = toDirectory(SystemPropertyUtil.get("io.netty.tmpdir"));
if (f != null) {
logger.debug("-Dio.netty.tmpdir: {}", f);
return f;
} f = toDirectory(SystemPropertyUtil.get("java.io.tmpdir"));
if (f != null) {
logger.debug("-Dio.netty.tmpdir: {} (java.io.tmpdir)", f);
return f;
} // This shouldn't happen, but just in case ..
if (isWindows()) {
f = toDirectory(System.getenv("TEMP"));
if (f != null) {
logger.debug("-Dio.netty.tmpdir: {} (%TEMP%)", f);
return f;
} String userprofile = System.getenv("USERPROFILE");
if (userprofile != null) {
f = toDirectory(userprofile + "\\AppData\\Local\\Temp");
if (f != null) {
logger.debug("-Dio.netty.tmpdir: {} (%USERPROFILE%\\AppData\\Local\\Temp)", f);
return f;
} f = toDirectory(userprofile + "\\Local Settings\\Temp");
if (f != null) {
logger.debug("-Dio.netty.tmpdir: {} (%USERPROFILE%\\Local Settings\\Temp)", f);
return f;
}
}
} else {
f = toDirectory(System.getenv("TMPDIR"));
if (f != null) {
logger.debug("-Dio.netty.tmpdir: {} ($TMPDIR)", f);
return f;
}
}
} catch (Exception ignored) {
// Environment variable inaccessible
} // Last resort.
if (isWindows()) {
f = new File("C:\\Windows\\Temp");
} else {
f = new File("/tmp");
} logger.warn("Failed to get the temporary directory; falling back to: {}", f);
return f;
} @SuppressWarnings("ResultOfMethodCallIgnored")
private static File toDirectory(String path) {
if (path == null) {
return null;
} File f = new File(path);
f.mkdirs(); if (!f.isDirectory()) {
return null;
} try {
return f.getAbsoluteFile();
} catch (Exception ignored) {
return f;
}
} /**
* 获取操作系统是多少位的32 或者64
* @return
*/
private static int bitMode0() {
// Check user-specified bit mode first.
int bitMode = SystemPropertyUtil.getInt("io.netty.bitMode", 0);
if (bitMode > 0) {
logger.debug("-Dio.netty.bitMode: {}", bitMode);
return bitMode;
} // And then the vendor specific ones which is probably most reliable.
bitMode = SystemPropertyUtil.getInt("sun.arch.data.model", 0);
if (bitMode > 0) {
logger.debug("-Dio.netty.bitMode: {} (sun.arch.data.model)", bitMode);
return bitMode;
}
bitMode = SystemPropertyUtil.getInt("com.ibm.vm.bitmode", 0);
if (bitMode > 0) {
logger.debug("-Dio.netty.bitMode: {} (com.ibm.vm.bitmode)", bitMode);
return bitMode;
} // os.arch also gives us a good hint.
String arch = SystemPropertyUtil.get("os.arch", "").toLowerCase(Locale.US).trim();
if ("amd64".equals(arch) || "x86_64".equals(arch)) {
bitMode = 64;
} else if ("x86".equals(arch) || "i386".equals(arch) || "i486".equals(arch) || "i586".equals(arch) || "i686".equals(arch)) {
bitMode = 32;
} if (bitMode > 0) {
logger.debug("-Dio.netty.bitMode: {} (os.arch: {})", bitMode, arch);
} // Last resort: guess from VM name and then fall back to most common 64-bit mode.
String vm = SystemPropertyUtil.get("java.vm.name", "").toLowerCase(Locale.US);
Pattern BIT_PATTERN = Pattern.compile("([1-9][0-9]+)-?bit");
Matcher m = BIT_PATTERN.matcher(vm);
if (m.find()) {
return Integer.parseInt(m.group(1));
} else {
return 64;
}
} private static int addressSize0() {
if (!hasUnsafe()) {
return -1;
}
return PlatformDependent0.addressSize();
} private PlatformDependent() {
// only static method supported
}
}