java开发常用工具类

package com.rui.util;

import java.text.DateFormat;
import java.text.DecimalFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Random;

/**
 * 
 * @ClassName: StrUtils
 * @Description: 工具类
 * @author poseidon
 * @date 2015年10月23日 下午8:13:45
 * @version V1.0.0
 */
public class StrUtils {


    /**
     * 
     * @Title: isEmpty
     * @Description: 空判断 
     * @param content
     * @return boolean
     */
    public static boolean isEmpty(String content){
        return (content==null || content.equals(""))?true:false;
    }
    
    /**
     * 
     * @Title: isNotEmpty
     * @Description: 非空判断
     * @param content
     * @return boolean
     */
    public static boolean isNotEmpty(String content){
        return !isEmpty(content);
    }
    
    
    /**
     * 
     * @Title: formatDate
     * @Description: 格式化日期类
     * @param date
     * @param pattern
     * @return String
     */
    public static String formatDate(Date date,String pattern){
        if(date!=null){
            String dateString = new SimpleDateFormat(pattern).format(date);
            return dateString;
        }else{
            return "";
        }
    }
    
    /**
     * 
     * @Title: getExt
     * @Description: 获取文件的后缀
     * @param name 文件名称
     * @param flag true有点false没点
     * @return String
     */
    public static String getExt(String name,boolean flag){
        if(isNotEmpty(name)){
            String ext  = null;
            if(flag){
                ext = name.substring(name.lastIndexOf("."), name.length());
            }else{
                ext = name.substring(name.lastIndexOf(".")+1, name.length());
            }
            return ext;
        }else{
            return "";
        }
    }
    
    /**
     * 
     * @Title: generateFileName
     * @Description: 为上传文件自动分配文件名称，避免重复
     * @param fileName
     * @param randomNum
     * @param dataPattern
     * @return String
     */
    public static String generateFileName(String fileName,int randomNum,String dataPattern) {
        // 获得当前时间
        DateFormat format = new SimpleDateFormat(dataPattern);
        // 转换为字符串
        String formatDate = format.format(new Date());
        // 随机生成文件编号
        int random = new Random().nextInt(randomNum);
        // 获得文件后缀名称
        int position = fileName.lastIndexOf(".");
        String extension = fileName.substring(position);
        // 组成一个新的文件名称
        return formatDate + random + extension;
    }
    
    
    /**
     * 
     * @Title: countFileSize
     * @Description: 根据File文件的长度统计文件的大小
     * @param fileSize
     * @return String
     */
    public static String countFileSize(long fileSize) {
        String fileSizeString = "";
        try {
            DecimalFormat df = new DecimalFormat("#.00");
            long fileS = fileSize;
            if (fileS == 0) {
                fileSizeString = "0KB";
            } else if (fileS < 1024) {
                fileSizeString = df.format((double) fileS) + "B";
            } else if (fileS < 1048576) {
                fileSizeString = df.format((double) fileS / 1024) + "KB";
            } else if (fileS < 1073741824) {
                fileSizeString = df
                        .format(((double) fileS / 1024 / 1024) - 0.01)
                        + "MB";
            } else {
                fileSizeString = df.format((double) fileS / 1024 / 1024 / 1024)
                        + "G";
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return fileSizeString;
    }
    
    /**
     * 
     * @Title: conversionSpecialCharacters
     * @Description: 把两个反斜线转换成正斜线
     * @param string
     * @return String
     */
    public static String conversionSpecialCharacters(String string) {
        return string.replaceAll("\\", "/");
    }

    public static void main(String[] args) {
        
        
    }
}