android edittext 限制文本框输入的长度和提示信息

package com.hwtt.android.oa.tool;

import android.content.Context;
import android.text.InputFilter;
import android.text.Spanned;
import android.widget.EditText;
import android.widget.Toast;

/**
* 字符串处理
* @author Administrator
*
*/
public class StringUtils {

/**
* 提示输入内容超过规定长度
* @param context
* @param editText
* @param max_length
* @param err_msg
*/
public static void lengthFilter( final Context context, EditText editText,
final int max_length, final String err_msg){

InputFilter[] filters = new InputFilter[1];
filters[0] = new InputFilter.LengthFilter(max_length){

@Override
public CharSequence filter(CharSequence source, int start, int end,
Spanned dest, int dstart, int dend) {
// TODO Auto-generated method stub
//获取字符个数(一个中文算2个字符)
int destLen = StringUtils.getCharacterNum(dest.toString());
int sourceLen = StringUtils.getCharacterNum(source.toString());
if(destLen + sourceLen > max_length){
Toast.makeText(context, err_msg,Toast.LENGTH_SHORT).show();
return "";
}
return source;

}

};
editText.setFilters(filters);
}

/**
*
* @param content
* @return
*/
public static int getCharacterNum(String content){
if(content.equals("")||null == content){
return 0;
}else {
return content.length()+getChineseNum(content);
}

}

/**
* 计算字符串的中文长度
* @param s
* @return
*/
public static int getChineseNum(String s){
int num = 0;
char[] myChar = s.toCharArray();
for(int i=0;i<myChar.length;i++){
if((char)(byte)myChar[i] != myChar[i]){
num++;
}
}
return num;
}
}

//超过长度提醒
StringUtils.lengthFilter(AddHolidayApplyActivity.this,
etReason, Constants.MAX_INPUT_LENGTG,
getString(R.string.max_length_holiday_warm));