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一、背景及样式效果      

因项目需要，需要文本编辑时，支持项目符号（无序列表）尝试了BulletSpan，但不是很理想，并且考虑到影响老版本回显等因素，最终决定自定义一个BulletEditText。

        先看效果：

二、自定义View BulletEditText        

        自定义控件BulletEditText源码：

package com.ml512.widgetimport android.content.Context
import android.util.AttributeSet
import androidx.core.widget.doOnTextChanged/*** @Description: 简单支持项目号的文本编辑器* @Author: Marlon* @CreateDate: 2024/2/1 17:44* @UpdateRemark: 更新说明：* @Version: 1.0*/
class BulletEditText : androidx.appcompat.widget.AppCompatEditText {/*** 是否开启项目符号*/private var isNeedBullet: Boolean = false/*** 项目符号*/private var bulletPoint: String = "• "/*** 项目符号占用字符数，方便设置光标位置*/private var bulletOffsetIndex = bulletPoint.length/*** 相关监听回调*/private var editListener: EditListener? = nullconstructor(context: Context) : super(context)constructor(context: Context, attrs: AttributeSet?) : super(context, attrs)constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(context,attrs,defStyleAttr)init {this.doOnTextChanged { text, start, before, count ->//如果是关闭状态不做格式处理if (!isNeedBullet) {return@doOnTextChanged}if (count > before) {//处理项目号逻辑var offset = 0var tmp = text.toString()//连续回车去掉项目符号if (start >= bulletOffsetIndex && tmp.substring(start, start + count) == "\n") {val preSub = tmp.substring(start - bulletOffsetIndex, start)if (preSub == bulletPoint) {changeBulletState(false)tmp = tmp.replaceRange(start-bulletOffsetIndex, start + count, "")offset -= bulletOffsetIndex + 1setTextAndSelection(tmp, start + count + offset)return@doOnTextChanged}}//加入项目符号if (tmp.substring(start, start + count) == "\n") {changeBulletState(true)tmp = tmp.replaceRange(start, start + count, "\n$bulletPoint")offset += bulletOffsetIndexsetTextAndSelection(tmp, start + count + offset)}}}}override fun onSelectionChanged(selStart: Int, selEnd: Int) {super.onSelectionChanged(selStart, selEnd)//复制选择时直接返回，关闭项目符号if (selStart != selEnd) {changeBulletState(false)return}//判断当前段落是否有项目号，有开启，没有关闭val tmp = text.toString()val prefix = tmp.substring(0, selectionStart)if (prefix.isEmpty()) {changeBulletState(false)return}if (prefix.startsWith(bulletPoint) && !prefix.contains("\n")) {changeBulletState(true)return}val lastEnterIndex = prefix.lastIndexOf("\n")if (lastEnterIndex != -1 && lastEnterIndex + bulletOffsetIndex + 1 <= prefix.length) {val mathStr = prefix.substring(lastEnterIndex, lastEnterIndex + bulletOffsetIndex + 1)if (mathStr == "\n$bulletPoint") {changeBulletState(true)return}}changeBulletState(false)}/*** 更新bullet状态*/private fun changeBulletState(isOpen: Boolean) {isNeedBullet = isOpeneditListener?.onBulletStateChange(isOpen)}/*** 设置是否开启项目号*/fun setBullet(isOpen: Boolean) {isNeedBullet = isOpenval tmp = text.toString()var index = selectionStartvar prefix = tmp.substring(0, index)val suffix = tmp.substring(index)//加项目号if (isOpen) {//首个段落if (!prefix.contains("\n") && prefix.startsWith(bulletPoint)) {return}index += bulletOffsetIndexif (prefix.isEmpty() || (!prefix.contains("\n") && !prefix.startsWith(bulletPoint))) {setTextAndSelection("$bulletPoint$prefix$suffix", index)return}prefix = prefix.replaceLast("\n", "\n$bulletPoint")setTextAndSelection("$prefix$suffix", index)return}//去掉项目号if (prefix.startsWith(bulletPoint) && !prefix.contains("\n$bulletPoint")) {//首行逻辑index -= bulletOffsetIndexprefix = prefix.replaceLast(bulletPoint, "")setTextAndSelection("$prefix$suffix", index)return}if (prefix.contains("\n$bulletPoint")) {index -= bulletOffsetIndexprefix = prefix.replaceLast("\n$bulletPoint", "\n")setTextAndSelection("$prefix$suffix", index)}}/*** 设置文本及光标位置*/private fun setTextAndSelection(text: String, index: Int) {setText(text)setSelection(index)}/*** 替换最后一个字符*/private fun String.replaceLast(oldValue: String, newValue: String): String {val lastIndex = lastIndexOf(oldValue)if (lastIndex == -1) {return this}val prefix = substring(0, lastIndex)val suffix = substring(lastIndex + oldValue.length)return "$prefix$newValue$suffix"}/*** 设置监听*/fun setEditListener(listener: EditListener) {editListener = listener}/*** 监听回调*/interface EditListener {/*** 项目符号开关状态变化*/fun onBulletStateChange(isOpen: Boolean)}
}

三、调用

        使用时一个项目符号的按钮开关设置调用setBullet(isOpen: Boolean) 设置是否开启项目符号，同时实现一个setEditListener(listener: EditListener)根据光标位置判断当前段落是否含有项目符号，并回显按钮状态。

 <com.ml512.widget.BulletEditTextandroid:id="@+id/etInput"android:layout_width="match_parent"android:layout_height="200dp"android:layout_below="@+id/tvTitle"android:layout_marginStart="15dp"android:layout_marginTop="15dp"android:layout_marginEnd="15dp"android:layout_marginBottom="15dp"android:autofillHints="no"android:background="@drawable/shape_edit_bg"android:gravity="top"android:hint="@string/text_please_input_some_worlds"android:inputType="textMultiLine"android:padding="15dp"android:textColor="@color/black"android:textColorHint="@color/color_FF_999999"android:textSize="16sp" />

        //点击按钮设置添加/取消项目符号tvBullet.setOnClickListener {tvBullet.isSelected = !tvBullet.isSelectedetInput.setBullet(tvBullet.isSelected)}//项目符号状态监听，回显到按钮etInput.setEditListener(object :BulletEditText.EditListener{override fun onBulletStateChange(isOpen: Boolean) {tvBullet.isSelected = isOpen}})

大功告成！