NIO 简单笔记

public static void main(String[] args) throws IOException {
        ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
        byteBuffer.putInt(1);
        byteBuffer.putChar('a');
        byteBuffer.flip();
        int anInt = byteBuffer.getInt();
        char aChar = byteBuffer.getChar();
        //读取顺序必须一致否则报错
        System.out.println(anInt);
        System.out.println(aChar);
    }

ByteBuffer 接口有4个类实现，后缀R表示只读。不可执行put方法，一旦执行，直接抛出异常，源码其实就是就是new一个异常。

DirectByteBuffer，DirectByteBufferR，HeapByteBuffer，HeapByteBufferR

默认的allcate方法就是返回的HeapByteBuffer

   public static ByteBuffer allocate(int capacity) {
        if (capacity < 0)
            throw new IllegalArgumentException();
        return new HeapByteBuffer(capacity, capacity);
    }