自定义EditText禁止输入表情

import android.content.Context;
import android.text.Editable;
import android.text.Selection;
import android.text.Spannable;
import android.text.TextWatcher;
import android.util.AttributeSet;
import android.widget.EditText;
import android.widget.Toast;

public class ContainsEmojiEditText extends EditText {
//输入表情前的光标位置
private int cursorPos;
//输入表情前EditText中的文本
private String inputAfterText;
//是否重置了EditText的内容
private boolean resetText;

private Context mContext;

public ContainsEmojiEditText(Context context) {
super(context);
this.mContext = context;
initEditText();
}

public ContainsEmojiEditText(Context context, AttributeSet attrs) {
super(context, attrs);
this.mContext = context;
initEditText();
}

public ContainsEmojiEditText(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
this.mContext = context;
initEditText();
}

// 初始化edittext 控件
private void initEditText() {
cursorPos = getSelectionEnd();
addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int before, int count) {
if (!resetText) {
cursorPos = getSelectionEnd();
//这里用s.toString()而不直接用s是因为如果用s，
// 那么，inputAfterText和s在内存中指向的是同一个地址，s改变了，
// inputAfterText也就改变了，那么表情过滤就失败了
inputAfterText = s.toString();

}

}

@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
if (!resetText) {

if(before != 0){

return;

}
if (count >= 2) {//表情符号的字符长度最小为2
CharSequence input = s.subSequence(cursorPos, cursorPos + count );
if (containsEmoji(input.toString())) {
resetText = true;
Toast.makeText(mContext, "不支持输入Emoji表情符号", Toast.LENGTH_SHORT).show();
//是表情符号就将文本还原为输入表情符号之前的内容
setText(inputAfterText);
CharSequence text = getText();
if (text instanceof Spannable) {
Spannable spanText = (Spannable) text;
Selection.setSelection(spanText, text.length());
}
}
}
} else {
resetText = false;
}
// cursorPos = getSelectionEnd();
}

@Override
public void afterTextChanged(Editable s) {

}
});
}

/**
* 检测是否有emoji表情
*
* @param source
* @return
*/
public static boolean containsEmoji(String source) {
int len = source.length();
for (int i = 0; i < len; i++) {
char codePoint = source.charAt(i);
if (!isEmojiCharacter(codePoint)) { //如果不能匹配,则该字符是Emoji表情
return true;
}
}
return false;
}

/**
* 判断是否是Emoji
*
* @param codePoint 比较的单个字符
* @return
*/
private static boolean isEmojiCharacter(char codePoint) {
return (codePoint == 0x0) || (codePoint == 0x9) || (codePoint == 0xA) ||
(codePoint == 0xD) || ((codePoint >= 0x20) && (codePoint <= 0xD7FF)) ||
((codePoint >= 0xE000) && (codePoint <= 0xFFFD)) || ((codePoint >= 0x10000)
&& (codePoint <= 0x10FFFF));
}

}