一、 实现方式
安卓原生的长按菜单，支持自定义菜单内容及事件，只需要两步设置便可快速实现：
val tvDemo: TextView
// 设置为可选中的，其内部会让控件支持长按
tvDemo.setTextIsSelectable(true)
tvDemo.customSelectionActionModeCallback = object : ActionMode.Callback {
override fun onCreateActionMode(mode: ActionMode?, menu: Menu?): Boolean {
// 开始创建ActionMode时回调，返回值为true表示要创建，false表示不创建
// 基本原理为：当前应用窗口根布局创建出Menu，然后Menu中创建ActionMode对应的按钮
}
override fun onPrepareActionMode(mode: ActionMode?, menu: Menu?): Boolean {
// 在Menu创建ActionMode后的准备工作，此时需要往Menu中塞入所需的MenuItem，也可以自定义SubMenu
// 返回值为true表示需要刷新按钮内容，为false的话，当关闭Menu后下次重新打开时会沿用之前的状态
}
override fun onActionItemClicked(mode: ActionMode?, item: MenuItem?): Boolean {
// Item的点击事件回调，通常在这里根据item的id来处理对应的自定义事件
// 如果自己消费了事件，应当返回true
}
override fun onDestroyActionMode(mode: ActionMode?) {
// 销毁ActionMode时回调，触发方式为主动调用ActionMode#finish()
}
}
二、 代码示例
为了提高代码的复用率，将其封装为一个基本控件，并提供默认的一些菜单功能：全选（仅对EditText生效）、复制、粘贴（仅对EditText生效）、@人名，以下是示例：
class CustomSelectionActionModeCallback(
val context: Context,
val view: TextView? = null
) : ActionMode.Callback {
private val menuItems = ArrayList<CustomMenuItem>(0)
override fun onCreateActionMode(mode: ActionMode?, menu: Menu?): Boolean {
return true
}
override fun onPrepareActionMode(mode: ActionMode?, menu: Menu?): Boolean {
menu?.let {
it.clear()
// 遍历自定义菜单项列表
menuItems.forEachIndexed {
index, item ->
// 逐一塞入菜单中
it.add(Menu.NONE, item.getId(), index, item.getTitle(context))
}
}
return true
}
override fun onActionItemClicked(mode: ActionMode?, item: MenuItem?): Boolean {
item?.itemId?.let {
val result = menuItems.find {
item ->
item.getId() == it
}?.getEvent()?.invoke() ?: false
if (result) {
mode?.finish()
}
}
return true
}
override fun onDestroyActionMode(mode: ActionMode?) {
}
fun addMenu(menuItem: CustomMenuItem) {
menuItems.add(menuItem)
}
fun removeMenu(item: CustomMenuItem) {
menuItems.remove(item)
}
/**
* 全选的item，直接返回文本
*/
class SelectAllMenuItem(textView: TextView, callback: EventCallback?) : CustomMenuItem(
"SELECT_ALL",
"全选",
{
if (textView is EditText) {
textView.selectAll()
val content = textView.text
val solved = callback?.beforeEvent(content) ?: content
callback?.onEvent(solved) == true
} else {
false
}
}
)
/**
* 复制的item，调用剪切板服务，将文本保存
*/
class CopyMenuItem(textView: TextView, callback: EventCallback?) : CustomMenuItem(
"COPY",
"复制",
{
val cms =
textView.context.getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager
val content = textView.text
val solved = callback?.beforeEvent(content) ?: content
cms.primaryClip = ClipData.newPlainText(null, solved)
callback?.onEvent(solved) == true
}
)
/**
* 粘贴的item，调用剪切板服务，将栈顶的文本粘贴到EditText中
*/
class PasteMenuItem(textView: TextView, callback: EventCallback?) : CustomMenuItem(
"PASTE",
"粘贴",
{
val cms =
textView.context.getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager
if (cms.hasPrimaryClip()) {
val content = cms.primaryClip?.getItemAt(0)?.text
if (textView is EditText) {
val solved = callback?.beforeEvent(content) ?: content
textView.setText(solved)
callback?.onEvent(solved) == true
} else {
false
}
} else {
false
}
}
)
/**
* @人名的item，通常由调用方实现业务，因此直接由回调接口返回
*/
class AtMenuItem(textView: TextView, callback: EventCallback?) : CustomMenuItem(
"AT",
"@TA",
{
val content = textView.text
val solved = callback?.beforeEvent(content) ?: content
callback?.onEvent(solved) == true
}
)
/**
* 自定义菜单item，需要传入item的id、标题、事件
*/
open class CustomMenuItem {
private val id: String
private var title: CharSequence? = null
private var titleRes: Int? = null
private val event: () -> Boolean
constructor(id: String, title: CharSequence, event: () -> Boolean) {
this.id = id
this.title = title
this.event = event
}
constructor(id: String, titleRes: Int, event: () -> Boolean) {
this.id = id
this.titleRes = titleRes
this.event = event
}
fun getId() = id.hashCode()
fun getTitle(context: Context): CharSequence? {
return title ?: titleRes?.let {
context.getString(it) }
}
fun getEvent() = event
override fun equals(other: Any?): Boolean {
return other is CustomMenuItem
&& id == other.id
&& title == other.title
&& titleRes == other.titleRes
&& event == other.event
}
}
/**
* 默认菜单功能的回调接口
*/
interface EventCallback {
/**
* @param content 原文本
* @return 处理后文本
*/
fun beforeEvent(content: CharSequence?): CharSequence? {
return content
}
/**
* @return true表示关闭menu
*/
fun onEvent(content: CharSequence?): Boolean
}
}
三、 运行效果
