Android EditText 银行卡四位空一格

/**
     * 设置银行卡输入时每隔4位多一位空格
     * @param cardEt
     */
    public static void bankCardInput(final EditText cardEt) {
        //设置输入长度不超过24位(包含空格)
        cardEt.setFilters(new InputFilter[]{new InputFilter.LengthFilter(24)});
        cardEt.addTextChangedListener(new TextWatcher() {
            char kongge = ' ';
            //改变之前text长度
            int beforeTextLength = 0;
            //改变之前的文字
            private CharSequence beforeChar;
            //改变之后text长度
            int onTextLength = 0;
            //是否改变空格或光标
            boolean isChanged = false;
            // 记录光标的位置
            int location = 0;
            private char[] tempChar;
            private StringBuffer buffer = new StringBuffer();
            //已有空格数量
            int konggeNumberB = 0;

            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
                beforeTextLength = s.length();
                if (buffer.length() > 0) {
                    buffer.delete(0, buffer.length());
                }
                konggeNumberB = 0;
                for (int i = 0; i < s.length(); i++) {
                    if (s.charAt(i) == ' ') {
                        konggeNumberB++;
                    }
                }
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                onTextLength = s.length();
                buffer.append(s.toString());
                if (onTextLength == beforeTextLength || onTextLength <= 3
                        || isChanged) {
                    isChanged = false;
                    return;
                }
                isChanged = true;
            }

            @Override
            public void afterTextChanged(Editable s) {
                if (isChanged) {
                    location = cardEt.getSelectionEnd();
                    int index = 0;
                    while (index < buffer.length()) {
                        if (buffer.charAt(index) == kongge) {
                            buffer.deleteCharAt(index);
                        } else {
                            index++;
                        }
                    }
                    index = 0;
                    int konggeNumberC = 0;
                    while (index < buffer.length()) {
                        if ((index == 4 || index == 9 || index == 14 || index == 19)) {
                            buffer.insert(index, kongge);
                            konggeNumberC++;
                        }
                        index++;
                    }

                    if (konggeNumberC > konggeNumberB) {
                        location += (konggeNumberC - konggeNumberB);
                    }

                    tempChar = new char[buffer.length()];
                    buffer.getChars(0, buffer.length(), tempChar, 0);
                    String str = buffer.toString();
                    if (location > str.length()) {
                        location = str.length();
                    } else if (location < 0) {
                        location = 0;
                    }

                    cardEt.setText(str);
                    Editable etable = cardEt.getText();
                    Selection.setSelection(etable, location);
                    isChanged = false;
                }
            }
        });

    }