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1、自定义格式取当期日期：
public String getMyDate(int type)
{
String date="";
Calendar cal = Calendar.getInstance();
int pm_am=cal.get(Calendar.AM_PM);
int hour=cal.get(Calendar.HOUR);
if(pm_am==Calendar.PM) hour+=12;
switch(type)
{
case 1: //yyyy-mm-dd
date+=cal.get(Calendar.YEAR)+"-"+(cal.get(Calendar.MONTH)+1)+"-"+cal.get(Calendar.DATE);
break;
case 2: //yyyy-mm-dd hh:mi:ss
date+=cal.get(Calendar.YEAR)+"-"+(cal.get(Calendar.MONTH)+1)+"-"+cal.get(Calendar.DATE)
+" "+hour+":"+cal.get(Calendar.MINUTE)+":"+ cal.get(Calendar.SECOND);
break;
default:
date+=null;
}
return date;
}
2、计算两时间差（天）：
/*
* Method:输出两日期差，单位（天）
*/
public long getQuot(String time1, String time2)
{
long quot = 0;
SimpleDateFormat ft = new SimpleDateFormat("yyyy-MM-dd");
try {
Date date1 = ft.parse( time1 );
Date date2 = ft.parse( time2 );
quot = date1.getTime() - date2.getTime();
quot = quot / 1000 / 60 / 60 / 24;
} catch (ParseException e) {
e.printStackTrace();
}
return quot;
}
3、转MYSQL的datetime日期类型：
/*
* Date类型转换为MYSQL DateTime类型
*/
public static String DateToMySQLDateTimeString(String date)
{
final String[] MONTH = {"Jan","Feb","Mar","Apr","May","Jun", "Jul","Aug","Sep","Oct","Nov","Dec",};
StringBuffer ret = new StringBuffer();
String dateToString = date.toString(); //like "Sat Dec 17 15:55:16 CST 2005"
ret.append(dateToString.substring(24,24+4));//append yyyy
String sMonth = dateToString.substring(4,4+3);
for(int i=0;i<12;i++) { //append mm
if(sMonth.equalsIgnoreCase(MONTH[i])) {
if((i+1) < 10)
ret.append("-0");
else
ret.append("-");
ret.append((i+1));
break;
}
}
ret.append("-");
ret.append(dateToString.substring(8,8+2));
ret.append(" ");
ret.append(dateToString.substring(11,11+8));
return ret.toString();
}
5、MD5加密方法：
// MD5加密方法
public static String change2MD5(String srcString)
{
MessageDigest md = null;
try
{
md = MessageDigest.getInstance("MD5");
}
catch (NoSuchAlgorithmException nsae)
{
return "";
}
byte[] md5Bytes = md.digest(srcString.getBytes());
int tmpInt = 0;
StringBuffer sb = new StringBuffer();
for (int i = 0; i < md5Bytes.length; i++)
{
tmpInt = (int) (md5Bytes[i] & 0xff);
if (tmpInt < 16)
{
sb.append("0");
}
sb.append(Integer.toHexString(tmpInt));
}
return sb.toString();
}
}
6、判断字符是否为0-9和英文字符：
// 判断字符串是否为合法字符
public static boolean isRegStr(String Str)
{
boolean flag=true;
Pattern p=null;
Matcher m=null;
try
{
p = java.util.regex.Pattern.compile("[^0-9A-Za-z]");
m = p.matcher(Str);
if(m.find()) flag=false;
}catch(Exception e)
{}
return flag;
}
7、判断邮件格式是否合法：
/*
*判断邮件格式
*/
public static boolean isEmail(String str)
{
if(str.length()<6||str.indexOf('@',0)==-1||str.indexOf('.',0)==-1)
{
return false;
}
else
{
return true;
}
}
8、替换换行与HTML符号：
//替换换行符号
public static String converLine(String str)
{
return str.replaceAll("\n", "
");
}
//替换HTML符
public static String converHtmlChar(String str)
{
str = str.replaceAll("&", "&");
str = str.replaceAll(" ", " ");
str = str.replaceAll("<", "<");
str = str.replaceAll(">", ">");
str = str.replaceAll("\"", """);
return str;
}
9、分割字符的方法：
//字符分割方法
public static final String[] split(String str, String delims)
{
StringTokenizer st = new StringTokenizer(str, delims);
ArrayList list = new ArrayList();
for(; st.hasMoreTokens(); list.add(st.nextToken()));
return (String[])list.toArray(new String[list.size()]);
}
10、JSP与Servlet处理字符乱码方式：
// 用于读数据库时由iso8859-1变为GBK
public static String GBKConverter(String s_string){
try{
String des = new String(s_string.getBytes("iso8859-1"),"gb2312");
return des;
}
catch(Exception ex){
String des="";
return des;
}
}
// 用于处理页内生成的中文数据在写入数据库时的处理，由GBK变为iso8859-1
public static String ISOConverter(String s_string){
try{
String des = new String(s_string.getBytes("gb2312"),"iso8859-1");
return des;
}
catch(Exception ex){
String des = "";
return des;
}
}
11、从数据源获取connection:
//从数据库源获取数据连接
public static Connection getConnectionFromDs()
{
Connection con=null;
DataSource ds=null;
Context context=null;
try {
//1连接到JNDI服务器
context=new InitialContext();
//2获取数据库源
ds=(DataSource)context.lookup("java:comp/env/jdbc/mysql-local");
con=ds.getConnection();
System.out.println("已获取数据库连接池！！");
} catch (NamingException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return con;
}
12、生成4位图片验证码：
public class CreateValidateCode extends HttpServlet {
// 生成随机种子
Random random = new Random();
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
protected void processRequest(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
response.setContentType("image/jpeg");
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
HttpSession session = request.getSession(true);
// 在内存中创建图象
int width = 50, height = 25;
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 获取图形上下文
Graphics g = image.getGraphics();
// 设定背景色
g.setColor(getRandColor(200, 250));
g.fillRect(0, 0, width, height);
// 设定字体
g.setFont(new Font("Georgia", Font.BOLD, 16));
// 画边框
// g.setColor(getRandColor(0,0));
// g.drawRect(0,0,width-1,height-1);
// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
g.setColor(getRandColor(160, 220));
for (int i = 0; i < 155; i++) {
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
g.drawLine(x, y, x + xl, y + yl);
}
// 取随机产生的认证码(4位数字)
String sRand = "";
for (int i = 0; i < 4; i++) {
String rand = createRandStr();
sRand += rand;
// 将认证码显示到图象中
g.setColor(new Color(40 + random.nextInt(110), 40 + random
.nextInt(110), 40 + random.nextInt(110)));
// 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
g.drawString(rand, 10 * i + 3, 18);
}
// 将认证码存入SESSION
session.setAttribute("rand", sRand);
// 图象生效
g.dispose();
ServletOutputStream responseOutputStream = response.getOutputStream();
// 输出图象到页面
ImageIO.write(image, "JPEG", responseOutputStream);
// 以下关闭输入流！
responseOutputStream.flush();
responseOutputStream.close();
}
public String createRandStr()
{
//Random random = new Random();
String str="";
String[] arr={"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"};
//for(int i=0;i<4;i++)
//{
int rand=random.nextInt(61);
str=arr[rand];
//}
return str;
}
Color getRandColor(int fc, int bc) {
// 给定范围获得随机颜色
Random random = new Random();
if (fc > 255)
fc = 255;
if (bc > 255)
bc = 255;
int r = fc + random.nextInt(bc - fc);
int g = fc + random.nextInt(bc - fc);
int b = fc + random.nextInt(bc - fc);
return new Color(r, g, b);
}
}
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