验证码倒计时工具类

class VerifyCodeUtil<T : TextView>(private val textView: T,
                                   private val defaultText: String = "发送验证码",
                                   private var countDown: Int = 60) {

    private var running = false

    private var runnable: Runnable = Runnable {
        if (!running) {
            return@Runnable
        }

        if (countDown-- == 0) {
            finish()
            return@Runnable
        }

        updateText()
    }

    // 开始倒计时
    fun start() {
        running = true
        textView.isEnabled = false
        startBlock(textView)
        updateText()
    }

    @SuppressLint("SetTextI18n")
    private fun updateText() {
        textView.text = "${countDown}s重新获取"
        textView.postDelayed(runnable, 1000L)
    }

    // 结束倒计时
    fun finish() {
        running = false
        textView.isEnabled = true
        textView.text = defaultText
        finishBlock(textView)
    }

    private var startBlock: (T) -> Unit = {}
    private var finishBlock: (T) -> Unit = {}

    fun doOnStart(startBlock: (T) -> Unit) = this.apply {
        this.startBlock = startBlock
    }

    fun doOnFinish(finishBlock: (T) -> Unit) = this.apply {
        this.finishBlock = finishBlock
    }
}

使用
  val verifyCodeUtil = VerifyCodeUtil(tv_get_verify_code)
                .doOnStart { it.solid = Color.GRAY }
                .doOnFinish { it.solid = Color.parseColor("#FF5818") }
                .apply {
                    this.start()    // 启动倒计时
                }

// 关闭倒计时
verifyCodeUtil.finish()