限制EditText最多输入多少汉字

mInputEditText.setFilters(new InputFilter[]{new InputLengthFilter(MAX_INPUT_SIZE)});

 
public class InputLengthFilter implements InputFilter {
 
    private final int mMax;
 
    public InputLengthFilter(int max) {
        //mMax = max*2;
        mMax = max;
    }
 
    /**
     *
     * @param source 新输入的字符串
     * @param start　新输入的字符串起始下标，一般为0
     * @param end　新输入的字符串终点下标，一般为source长度-1
     * @param dest　输入之前文本框内容
     * @param dstart　原内容起始坐标，一般为0
     * @param dend　原内容终点坐标，一般为dest长度-1
     * @return
     */
    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
        int destSize = dest.length();
        int spill = 0;
        //无须区别对待汉字,　需求为１中文＝１标点＝１数字＝１符号,表情[微笑]相当于４个中文长度
//        for(int i=0;i<destSize;i++){
//            char c = dest.charAt(i);
//            if((char)(byte)c!=c){//中文
//                spill ++;
//            }
//        }
        int keep = mMax - (destSize + spill - (dend - dstart));
 
        if (keep <= 0) {
            return "";
        } else if (keep >= end - start) {
            return null; // keep original
        } else {
            keep += start;
            if (Character.isHighSurrogate(source.charAt(keep - 1))) {
                --keep;
                if (keep == start) {
                    return "";
                }
            }
            int sourceSpill = 0;
            int size = source.length();
            for(int i=0;i<size;i++){
                //同上
//                char c = source.charAt(i);
//                if((char)(byte)c!=c){//中文
//                    sourceSpill ++;
//                }
                if(keep <= sourceSpill+i){
                    return source.subSequence(start, i);
                }
            }
            return source.subSequence(start, keep);
        }
    }
}