Android Kotlin 实现底部弹框日历组件的案例

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="#98ADABAB">
    <RelativeLayout
        android:id="@+id/dialog_bottom"
        android:layout_width="match_parent"
        android:layout_height="320dp"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:background="@drawable/rounded_button_white"
        android:padding="20dp">
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginBottom="40dp">
            <TextView
                android:id="@+id/cancel"
                android:layout_width="0dp"
                android:layout_weight="1.5"
                android:layout_height="38dp"
                android:layout_gravity="center_horizontal"
                android:text="Cancel"
                android:textAllCaps="false"
                android:textColor="@color/colorPrimary"
                android:textSize="14sp"
                android:gravity="center"
                />
            <TextView
                android:id="@+id/title"
                android:layout_width="0dp"
                android:layout_weight="5"
                android:layout_height="38dp"
                android:layout_gravity="center_horizontal"
                android:text="Date of Birth"
                android:textAllCaps="false"
                android:textColor="@color/colorPrimary"
                android:textSize="16sp"
                android:gravity="center"
                />
            <TextView
                android:id="@+id/save"
                android:layout_width="0dp"
                android:layout_weight="1.5"
                android:layout_height="38dp"
                android:layout_gravity="center_horizontal"
                android:layout_marginTop="139dp"
                android:text="Save"
                android:textAllCaps="false"
                android:gravity="center"
                android:textColor="@color/colorPrimary"
                android:textSize="14sp" />
        </LinearLayout>
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="40dp"
            android:gravity="center_horizontal"
            android:orientation="vertical">
            <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:orientation="vertical"
                android:padding="5dp">
				// 这个是最关键的
                <DatePicker
                    android:id="@+id/dp_date"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:calendarViewShown="false"
                    android:datePickerMode="spinner"
                    />
            </LinearLayout>
        </LinearLayout>
    </RelativeLayout>
</RelativeLayout>

import java.util.Date
/**
 * 个人信息页
 */
class PersonnalInfoActivity : AppCompatActivity() {
    private var year: String? = null
    private var month: String? = null
    private var day: String? = null
    @RequiresApi(Build.VERSION_CODES.N)
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_personal_info)
        birthday.setOnClickListener {
            chooseBirthFun()
        }
    }
    private fun chooseBirthFun() = run {
        val userInfo = SharedPrefs.loadUserFromPreferences(this@PersonnalInfoActivity)
        val view = layoutInflater.inflate(R.layout.custom_bottom_datepicker, null)
        val popupWindow = PopupWindow(
            view,
            ViewGroup.LayoutParams.MATCH_PARENT,
            ViewGroup.LayoutParams.MATCH_PARENT,
            true
        )
        // 设置PopupWindow是否能响应外部点击事件
        popupWindow.isOutsideTouchable = true
        // 设置PopupWindow是否能响应点击事件
        popupWindow.isTouchable = true
        // 设置PopupWindow弹出窗体的背景
        popupWindow.setBackgroundDrawable(
            ColorDrawable(
                ContextCompat.getColor(
                    this,
                    android.R.color.transparent
                )
            )
        )
        // 设置PopupWindow从底部弹出
        popupWindow.showAtLocation(view, Gravity.BOTTOM, 0, 0)
        val save = view.findViewById<TextView>(R.id.save)
        val cancel = view.findViewById<TextView>(R.id.cancel)
        val dpDate = view.findViewById<DatePicker>(R.id.dp_date);
        // 设置默认日期
        if (userInfo != null) {
            if (userInfo.birthday == "") {
                dpDate.init(1970, 0, 1, null);
            } else {
                year?.let {
                    (month)?.let { it1 ->
                        day?.let { it2 ->
                            dpDate.init(
                                it.toInt(),
                                (it1.toInt()) - 1,
                                it2.toInt(),
                                null
                            )
                        }
                    }
                };
            }
        }
        save.setOnClickListener {
            if (popupWindow.isShowing) {
                year = dpDate.getYear().toString()
                month = ((dpDate.getMonth() + 1).toString())
                day = dpDate.getDayOfMonth().toString()
                val birthStr = "${year}-${month}-${day}"
                // 此处可以处理选择好的日期
                popupWindow.dismiss()
            }
        }
        cancel.setOnClickListener {
            if (popupWindow.isShowing) {
                popupWindow.dismiss()
            }
        }
    }
}