import java.nio.ByteBuffer;
public class JavaTest {
    public static void main(String[] args)
    {
        System.out.println("~~~~~~~~ put(byte b) ~~~~~~~~");
        // 分配一個(gè)5字節(jié)的buffer
        ByteBuffer byteBuffer = ByteBuffer.allocate(5);
        // 向buffer中添加兩個(gè)字節(jié)的數(shù)據(jù)，空余3個(gè)字節(jié)數(shù)據(jù)
        byteBuffer.put((byte)10);
        byteBuffer.put((byte)20);
        // 輸出整個(gè)字節(jié)數(shù)組
        printByteBuffer(byteBuffer);
        System.out.println("~~~~~~~~ flip() ~~~~~~~~");
        // 轉(zhuǎn)為讀模式
        byteBuffer.flip();
        // 輸出整個(gè)字節(jié)數(shù)組
        printByteBuffer(byteBuffer);
        System.out.println("~~~~~~~~ get() ~~~~~~~~");
        // 讀取當(dāng)前 position 
        System.out.println(byteBuffer.get());
        // 輸出整個(gè)字節(jié)數(shù)組
        printByteBuffer(byteBuffer);
        System.out.println("~~~~~~~~ rewind() ~~~~~~~~");
        // 倒回緩沖區(qū)的初始位置
        byteBuffer.rewind();
        printByteBuffer(byteBuffer);
        System.out.println("~~~~~~~~ get(byte[] dst, int offset, int length) ~~~~~~~~");
        // 將buffer中數(shù)據(jù)寫入到dstBytes中
        byte[] dstBytes = new byte[2];
        byteBuffer.get(dstBytes, 0, dstBytes.length);
        printByteBuffer(byteBuffer);
    }
    public static void printByteBuffer(ByteBuffer byteBuffer) {
        byte[] bytes = byteBuffer.array();
        int position = byteBuffer.position();
        int limit = byteBuffer.limit();
        int remining = byteBuffer.remaining();
        System.out.println("byteBuffer: "
                + Arrays.toString(bytes)
                + "\nPosition: " + position
                + " Limit: " + limit
                + " Remining: " + remining);
    }
}

mark <= position <= limit <= capacity ???????

ByteBuffer byteBuffer = ByteBuffer.allocate(5); 

byteBuffer.put((byte)'a') 

byteBuffer.get()