Android EditText字数限制：中文算2个字符，英文数字算1个字符，超出后弹Toast

最近有这个需求，在编辑框中输入字符，有长度的限制，中文算2个字符，英文算1个字符

1、中文、英文、数字都算一个字符：

[code]/**
* @author pengbo
* @date 2018/11/12
* 汉字、英文、数字都算一位，超出位数弹吐司
*/

public class MaxTextNormalLengthFilter implements InputFilter{
private int mMaxLength;
private Toast toast;

public MaxTextNormalLengthFilter(Context context, int maxLen){
mMaxLength = maxLen;
toast = Toast.makeText(context, "限"+ maxLen + "个字符！)", Toast.LENGTH_SHORT);
toast.setGravity(Gravity.CENTER, 0, 0);
}

@Override
public CharSequence filter(CharSequence source, int start, int end,
Spanned dest, int dstart , int dend){
// 判断是否到达最大长度
int count = 0;
// 之前就存在的内容
int dindex = 0;
while (count <= mMaxLength && dindex < dest.length()) {
count++;
dindex++;
}
if (count > mMaxLength) {
toast.show();
return dest.subSequence(0, dindex - 1);
}
// 从编辑框刚刚输入进去的内容
int sindex = 0;
while (count <= mMaxLength && sindex < source.length()) {
count++;
sindex++;
}
if (count > mMaxLength) {
toast.show();
sindex--;
}
return source.subSequence(0, sindex);
}
}

2、中文算2个字符、英文和数字算1个字符：

[code]/**
* @author pengbo
* @date 2018/11/8
* 数字英文算一位，中文算两位，超出位数弹吐司
*/
public class MaxTextTwoLengthFilter implements InputFilter {

private int mMaxLength;
private Toast toast;

public MaxTextTwoLengthFilter(Context context, int maxLen){
mMaxLength = maxLen;
toast = Toast.makeText(context, "限" + maxLen / 2 + "个汉字或" + maxLen + "个数字英文！)", Toast.LENGTH_SHORT);
toast.setGravity(Gravity.CENTER, 0, 0);
}

@Override
public CharSequence filter(CharSequence source, int start, int end,
Spanned dest, int dstart , int dend){
// 判断是否到达最大长度
int count = 0;
// 之前就存在的内容
int dindex = 0;
while (count <= mMaxLength && dindex < dest.length()) {
char c = dest.charAt(dindex++);
if (c < 128) {
count = count + 1;
} else {
count = count + 2;
}
}
if (count > mMaxLength) {
toast.show();
return dest.subSequence(0, dindex - 1);
}
// 从编辑框刚刚输入进去的内容
int sindex = 0;
while (count <= mMaxLength && sindex < source.length()) {
char c = source.charAt(sindex++);
if (c < 128) {
count = count + 1;
} else {
count = count + 2;
}
}
if (count > mMaxLength) {
toast.show();
sindex--;
}
return source.subSequence(0, sindex);
}
}

3、如果有那种输入大量篇幅的，肯定有一个字数的提示，或者在编辑框中输入了内容之后需要回调：

[code]/**
* @author pengbo
* @date 2018/11/12
* EditText添加文字限制的时候使用此TextWatcher,
* 提供回调，有部分界面使用到判断
*/

public class MaxEditTextWatcher implements TextWatcher {
/** 都算一位或 中文算两位 */
public static final int ALL_ONE = 0;
public static final int CHINESE_TWO = 1;
private int mType;
private int mMaxLen;
private Context mContext;
private EditText etText;
private TextView tvByteLimit;
private TextChangedCallBack mCallBack;

public MaxEditTextWatcher(int type, int maxlen, Context context,  EditText editText) {
this(type, maxlen, context, editText, null);
}

public MaxEditTextWatcher(int type, int maxLen, Context context, EditText editText, TextView textView) {
this(type, maxLen, context, editText, textView, null);
}

public MaxEditTextWatcher(int type,int maxLen, Context context, EditText editText, TextView textView,
TextChangedCallBack callBack) {
mType = type;
mMaxLen = maxLen;
mContext = context;
etText = editText;
tvByteLimit = textView;
mCallBack = callBack;
if (mType == ALL_ONE) {
etText.setFilters(new InputFilter[]{new MaxTextNormalLengthFilter(mContext, mMaxLen)});
} else if (mType == CHINESE_TWO){
etText.setFilters(new InputFilter[]{new MaxTextTwoLengthFilter(mContext, mMaxLen)});
}
}

@Override
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

}

@Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {

}

@Override
public void afterTextChanged(Editable editable) {
if (tvByteLimit != null) {
if (mType == ALL_ONE) {
int length = etText.getText().length();
tvByteLimit.setText(length + "/" + mMaxLen);
} else if (mType == CHINESE_TWO) {
int length = CommonUtil.judgeTextLength(etText.getText().toString());
tvByteLimit.setText(length + "/" + mMaxLen);
}
}

if (mCallBack != null) {
mCallBack.changed(editable);
}
}

public interface TextChangedCallBack {
void changed(Editable editable);
}
}

CommonUtil:

[code]  /**
* 返回text的长度，一个汉字算两个，数字和英文算一个
* @param text
* @return
*/
public static int judgeTextLength(String text) {
if (TextUtils.isEmpty(text)) {
return 0;
}
int count = 0;
for (int i = 0; i < text.length(); i++) {
char item = text.charAt(i);
if (item < 128) {
count++;
} else {
count += 2;
}
}
return count;
}