android BLE 分包发送数据

package com.example.bluetooth.le.packet;
import java.util.linkedList;
import java.util.List;

/**
 * 发送指令分包
 */
public class BlePacketUtil {
    /**
     * 默认一包发送20字节数据
     */
    private static final int BUFFER_SIZE = 20;

    /**
     * 分包发送数据
     *
     * @param data 发送数据
     */
    public static List writeEntity（byte[] data） {
        if （data == null） {
            return null;
        }
        List packDataList = new linkedList（）;
        int index = 0;
        int runSize = 0;
        int lastDataSize = 0;
        int length = data.length;
        while （index < length） {
            byte[] txBuffer = new byte[BUFFER_SIZE];
            for （int i = 0; i < BUFFER_SIZE; i++） {
                if （index < length） {
                    txBuffer[i] = data[index++];
                }
                runSize++;
            }
            if （length == index） {
                lastDataSize = BUFFER_SIZE - （runSize - index）;
                byte[] lastBuffer = new byte[lastDataSize]