常用到的util类，记录一下

package com.atmu.report.util;


import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.List;
import java.util.Properties;

import org.apache.log4j.Logger;
public class Util {
	
	private static Logger logger=Logger.getLogger(Util.class);
	
	/**
	 * 返回子byte数组
	 */
	public static byte[] subByte(byte[] b,int begin,int end){
		byte[] ret=new byte[end-begin];
		for(int i=0;i<ret.length;i++)
			ret[i]=b[begin+i];
		return ret;
	}
	
	/**
	 * 合并两个数组
	 * @param b1
	 * @param b2
	 * @return
	 */
	public static byte[] mergeByte(byte[] b1,byte[] b2){
		if (b1==null)
			return b2;
		if (b2==null)
			return b1;
		byte[] ret=new byte[b1.length+b2.length];
		System.arraycopy(b1, 0, ret, 0, b1.length);
		System.arraycopy(b2, 0, ret, b1.length, b2.length);
		return ret;
	}
	
	/**
	 * 
	 * @param b
	 * @param startpos
	 * @param delimiter
	 * @return 指定分隔符的数组
	 */
	public static byte[] subByteDelimiter(byte[] b,int startpos,char delimiter){
		byte[] ret=new byte[1024];
		int i=0;
		for(;i<1024;i++){
			if(b[startpos+i]==delimiter)
				break;
			else{
				ret[i]=b[startpos+i];
			}
		}
		ret=subByte(ret,0,i);
		return ret;
		
	}
	/**
	 * 
	 * @param s:#{A41} + #{A42} - #{A43}
	 * @param delimiter1	{
	 * @param delimiter2	}
	 * @return
	 */
	
	public static String[] DemarkString(String s,char delimiter1,char delimiter2){
		String[] ret=null;
		String[] temp=s.split("#");
		ret=new String[temp.length-1];
		String item="";
		for(int i=1;i<=ret.length;i++){
			item=temp[i];
			//Log.info(item);
			ret[i-1]=item.substring(item.indexOf(delimiter1)+1, item.indexOf(delimiter2));
		}
		
		return ret;
	}
	
	
	/**
	 * 
	 * @param date1
	 * @param date2
	 * @return date2-date1
	 * @throws ParseException 
	 */
	public static long gettimeDiff(String startDate,String endDate) throws ParseException{
		SimpleDateFormat sd=new SimpleDateFormat("yyyyMMddHHmmss");
		Date d1=sd.parse(startDate);
		Date d2=sd.parse(endDate);
		return d2.getTime()-d1.getTime();
	}
	
	/**
	 * 
	 * @param date
	 * @param format
	 * @return 指定格式的日期字符串形式
	 * @throws Exception 
	 */
	public static String format(String date,String format_source,String format_target) throws Exception{
		SimpleDateFormat sd=new SimpleDateFormat(format_source);
		Date d1=sd.parse(date);
		sd=new SimpleDateFormat(format_target);
		return sd.format(d1);
	}
	
	public static void main(String[] args){
	/*	String s="abcdef|eaac";
		byte[] b=s.getBytes();
		String ss=new String(subByteDelimiter(b,1,'|'));
		
		String[] ssa=DemarkString("#{A41}",'{','}');
		
		for(String sss:ssa)
		System.out.println(sss);*/
		System.out.println(getDate("19960229",-1,2));
		
		
		/*String date1="20091207124900";
		String date2="20091207124901";
		try {
			logger.info(gettimeDiff(date1,getCurrentDate()+getCurrentTime()));
		} catch (ParseException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		logger.info("["+FomatNumber(2,2)+"]");*/
	}
	
	/**
	 * 
	 * @return 系统日期
	 */
	public static String getCurrentDate(){
		SimpleDateFormat sd=new SimpleDateFormat("yyyyMMdd");
		return sd.format(new Date());
	}
	
	public static String getYesterday(){
		Calendar ca=new GregorianCalendar();
		ca.add(Calendar.DAY_OF_MONTH, -1);
		return getDateFromCa(ca);
		/*Date d = ca.getTime();
		SimpleDateFormat sd=new SimpleDateFormat("yyyyMMdd");
		return sd.format(d);*/
	}
	
	/**
	 * 
	 * @param referDate 20100120
	 * @param datediff
	 * @return 根据指定日期与差别天数得到的新日期
	 */
	public static String getDate(String referDate,int datediff,int type){
		try{
			int day=Integer.parseInt(referDate.substring(6));
			int month=Integer.parseInt(referDate.substring(4,6));
			int year=Integer.parseInt(referDate.substring(0,4));
			Calendar ca=new GregorianCalendar(year,month-1,day);
			switch(type){
			case 0:
				ca.add(Calendar.DAY_OF_MONTH, datediff);
				break;
			case 1:
				ca.add(Calendar.MONTH, datediff);
				break;
			case 2:
				ca.add(Calendar.YEAR, datediff);
			case 3:
				ca.add(Calendar.WEEK_OF_YEAR, datediff);
				break;
			}
			
			return getDateFromCa(ca);
		}catch(Exception e){
			logger.warn("",e);
		}
		return null;
	}
	
	public static String getDateFromCa(Calendar ca){
		Date d = ca.getTime();
		SimpleDateFormat sd=new SimpleDateFormat("yyyyMMdd");
		return sd.format(d);
	}
	
	public static String getCurrentTime(){
		SimpleDateFormat sd=new SimpleDateFormat("yyyyMMddHHmmss");
		return sd.format(new Date()).substring(8);
	}
	
	public static String getFullCurrentTime(){
		SimpleDateFormat sd=new SimpleDateFormat("yyyyMMddHHmmssSSS");
		return sd.format(new Date());
	}
	
	public static long getlongtime(){
		return (new Date()).getTime();
	}
	
	/**
	 * 格式化字符串，右补空格
	 * @param s
	 * @param width
	 * @return
	 */
	public static String formateString(String s,int width){
		String format="%1$-"+width+"s";
		return String.format(format, s);
	}
	
	/**
	 * 格式化字符串，左补空格
	 * @param s
	 * @param width
	 * @return
	 */
	public static String RfillBlank(String s,int width){
		String format="%1$"+width+"s";
		return String.format(format, s);
	}
	
	public static String getPartitionKey(){
		SimpleDateFormat sd=new SimpleDateFormat("yyyyMM");
		return sd.format(new Date());
	}

	
	/**
	 * 测试用
	 * @param map
	 */
	public static void writeObject(Object request,String filename) {
		ObjectOutputStream out;
		try {
			out = new ObjectOutputStream(new FileOutputStream("data/"+filename+"-request.ser"));
			out.writeObject(request);
			out.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	/**
	 * 测试用
	 * @param map
	 */
	public static Object readObject(String filename) {
		ObjectInputStream in;
		File f = new File("data/"+filename+"-request.ser");
		if (!f.exists())
			return null;
		try {
			in = new ObjectInputStream(new FileInputStream("data/"+filename+"-request.ser"));
			Object ret = in.readObject();
			in.close();
			return ret;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;

	}
	
	/**
	 * 从文本生成hashmap对象
	 * @return
	 */
	public static  HashMap readFromText(){
		Properties p=new Properties();
		HashMap ret=new HashMap();
		try {
			p.load(new FileInputStream("test/hashmap.txt"));
		} catch (Exception e) {
			logger.warn("",e);
		}
		ret.putAll(p);
		return ret;
	}

	/**
	 * /**
	 * 填充数组到指定长度
	 * @param ret
	 * @param len
	 */
	public static byte[] fillByteLen(byte[] ret, int len) {
		byte[] subbyte=null;
		
		if(ret!=null&&len<ret.length){
			logger.warn("param:ret"+new String(ret));
			logger.warn("param:len"+len);
			return subByte(ret,0,len);
		}
		try{
			if(ret!=null){
				subbyte=new byte[len-ret.length];
			}else{
				subbyte=new byte[len];
			}
			
			for (int i = 0; i < subbyte.length; i++) {
				subbyte[i] = 0x20;
			}
			
			ret=mergeByte(ret,subbyte);
		}catch(Exception e){
			logger.warn("Error:",e);
			logger.warn("param:ret"+new String(ret));
			logger.warn("param:len"+len);
		}
		
		return ret;
		
		
	}
	
	//String.format("%03d",cmds[5].getBytes().length)
	/**
	 * 格式化数字,左补0
	 */
	public static String FomatNumber(int width,int data){
		String format="%0"+width+"d";
		return String.format(format, data);
	}

	/**
	 * 判断list为空
	 * @param l
	 * @return
	 */
	public static boolean AssertListEmpty(List l) {
		if(l==null||l.size()==0){
			return true;
		}else{
			return false;
		}
	}
	
}