java DirectBuffer，释放

Question

我分配了一个直接缓冲区：

ByteBuffer directBuffer = ByteBuffer.allocateDirect(1024);

我读过：

Deallocating Direct Buffer Native Memory in Java for JOGL

但它没有直接回答

总结一下：

1. GC将在启动GC时释放directbuffer，而directbuffer未被引用。在链接帖子中写道：

When you know that a direct NIO buffer has become useless for you, you have to release its native memory by using its sun.misc.Cleaner (StaxMan is right) and call clean() (except with Apache Harmony), call free() (with Apache Harmony) or use a better public API to do that (maybe in Java >= 1.9, AutoCleaning that extends AutoCloseable?).

但我没有看到如何显式释放内存块。好的，有一个sun.misc.Cleaner什么

Cleaner c = new Cleaner()

1. 使用DirectBuffer而不是Unsafe.allocateMemory的目的是什么

2. 
   

This solution (in this JEP, still a draft, probably not available in Java 1.9) is very promising, we won't need to use non public APIs.

public long memory(long index) {
    // The scope where the memory region is available
    // Implements AutoClosable but `close` can be called manually as well
    try (Scope scope = new NativeScope()) {
        // Allocate the actual memory area, in this case in the style of a "long-array"
        Pointer<Long> ptr = scope.allocate(
                    NativeLibrary.createLayout(long.class), numElements);

        // Get the reference to a certain element
        Reference<Long> ref = ptr.offset(index).deref();

        // Set a value to this element through the reference
        ref.set(Long.MAX_VALUE);

        // Read the value of an element
        return ref.get();
    }
}

它看起来像C++中的智能指针，不是吗？p>