kotlin建造者模式(Builder)实践

(Updated: )
kotlin

后来又开始写安卓，士别三日党刮目相看，我这是别了大概两年多吧，kotlin已经不再新鲜，IO大会出现了很多新特性，Instant run，Android Q bla bla不管他，不管被拉下多远还是要操练起来。

现状是目前的安卓项目中已经集成了kotlin的一个插件，信息提示的，比较炫酷，长这个样子 => 传送门

好吧，放了两天都不知道要说什么了，只记得最后加了个onShow和onHide的回调，用来满足业务需求，例如请求api发现客户端token无效或超时而要求用户重新登录，封装了一个Util，直接贴代码。

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/**
 * Created by Lison on 7/9/2019.
 *
 * http://lison.cc
 */
class AlerterUtil(
        val activity: Activity,
        val title: String,
        val titleId: Int,
        val text: String,
        val textId: Int,
        val backgroundColor: Int,
        val icon: Int,
        val showAlertListener: OnShowAlertListener,
        val hideAlertListener: OnHideAlertListener
) {
    private constructor(builder: Builder) : this(builder.activity, builder.title, builder.titleId, builder.text, builder.textId, builder.backgroundColor, builder.icon, builder.showAlertListener, builder.hideAlertListener)

    class Builder {

        /** lateinit 可以只創建變量不賦值 **/
        lateinit var activity: Activity
            private set
        var title: String = ""
            private set
        var titleId: Int = 0
            private set
        var text: String = ""
            private set
        var textId: Int = 0
            private set
        var backgroundColor: Int = 0
            private set
        var icon: Int = 0
            private set

        var showAlertListener: OnShowAlertListener = OnShowAlertListener { }
            private set
        var hideAlertListener: OnHideAlertListener = OnHideAlertListener { }
            private set

        constructor(activity: Activity) {
            this.activity = activity
        }

        fun title(title: String) = apply {
            this.title = title
        }

        fun title(titleId: Int) = apply { this.titleId = titleId }

        fun text(text: String) = apply {
            this.text = text
        }

        fun text(textId: Int) = apply { this.textId = textId }

        fun backGroundColor(color: Int) = apply {
            this.backgroundColor = color
        }

        fun icon(icon: Int) = apply {
            this.icon = icon
        }

        fun onShowAlertListener(onShowAlertListener: OnShowAlertListener) = apply {
            this.showAlertListener = onShowAlertListener
        }

        fun onHideAlertListener(onHideAlertListener: OnHideAlertListener) = apply {
            this.hideAlertListener = onHideAlertListener
        }

        fun build() = AlerterUtil(this)

        fun ok() = apply {
            backgroundColor = R.color.colorSpring
            icon = R.drawable.icon_ok
        }

        fun warn() = apply {
            backgroundColor = R.color.colorAlert
        }

        fun error() = apply {
            backgroundColor = R.color.colorError
            icon = R.drawable.icon_error
        }
    }

    fun alert() {
        var al = Alerter.create(activity)
        if (TextUtil.isNotBlank(title))
            al.setTitle(title)
        else if (titleId != 0)
            al.setTitle(titleId)

        if (TextUtil.isNotBlank(text))
            al.setText(text)
        else if (textId != 0)
            al.setText(textId)

        if (backgroundColor != 0)
            al.setBackgroundColorRes(backgroundColor)
        else
            al.setBackgroundColorRes(R.color.colorPrimary)
        if (icon != 0)
            al.setIcon(icon)

        if (showAlertListener != null)
            al.setOnShowListener(showAlertListener)
        if (hideAlertListener != null)
            al.setOnHideListener(hideAlertListener)

        al.show()
    }

调用方式如下

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new AlerterUtil.Builder(this).text(getString(R.string.need_barcode)).onHideAlertListener(new OnHideAlertListener() {
    @Override
    public void onHide() {
        //打开登录Activity
    }
}).build().alert();

kotlin是个好东西，与java无缝衔接；设计模式更是把好武器。好了好了困了。

参考资料： https://www.cnblogs.com/scuwangjun/p/9699895.html https://github.com/Tapadoo/Alerter https://stackoverflow.com/questions/36140791/how-to-implement-builder-pattern-in-kotlin