有趣的是，我甚至从未听说过这个类(这可能是一件好事，真的)。

我想到的一件事是使用Unsafe#setMemory将包含敏感信息的缓冲区归零(密码、密钥等)。您甚至可以对“不可变”对象的字段执行此操作(然后，我再次假设普通的反射也可以在这里执行此操作)。但我不是安全专家，所以对此持保留态度。

not safe.park()和not safe.unpark()用于构建自定义并发控制结构和协作调度机制。

堆外集合对于分配大量内存并在使用后立即释放内存而不受GC干扰可能很有用。我基于sun.misc.Unsafe编写了一个用于处理堆外数组/列表的库。

我们使用Unsafe实现了数组、HashMaps、TreeMaps等大型集合。为了避免/最小化碎片，我们使用dlmalloc over unsafe的概念实现内存分配器。这帮助我们获得了并发性方面的性能。

我自己没有使用过它，但我认为如果你有一个变量，只是偶尔被多个线程读取(所以你真的不想让它volatile)，你可以在主线程中写入它时使用putObjectVolatile，在从其他线程中进行罕见的读取时使用readObjectVolatile。

例子

VM "intrinsification." ie CAS (Compare-And-Swap) used in Lock-Free Hash Tables eg:sun.misc.Unsafe.compareAndSwapInt it can make real JNI calls into native code that contains special instructions for CAS read more about CAS here http://en.wikipedia.org/wiki/Compare-and-swap The sun.misc.Unsafe functionality of the host VM can be used to allocate uninitialized objects and then interpret the constructor invocation as any other method call. One can track the data from the native address.It is possible to retrieve an object’s memory address using the java.lang.Unsafe class, and operate on its fields directly via unsafe get/put methods! Compile time optimizations for JVM. HIgh performance VM using "magic", requiring low-level operations. eg: http://en.wikipedia.org/wiki/Jikes_RVM Allocating memory, sun.misc.Unsafe.allocateMemory eg:- DirectByteBuffer constructor internally calls it when ByteBuffer.allocateDirect is invoked Tracing the call stack and replaying with values instantiated by sun.misc.Unsafe, useful for instrumentation sun.misc.Unsafe.arrayBaseOffset and arrayIndexScale can be used to develop arraylets,a technique for efficiently breaking up large arrays into smaller objects to limit the real-time cost of scan, update or move operations on large objects http://robaustin.wikidot.com/how-to-write-to-direct-memory-locations-in-java

更多的参考资料在这里- http://bytescrolls.blogspot.com/2011/04/interesting-uses-of-sunmiscunsafe.html