常用的java Utils总结

HibernateUtils
   public class HibernateUtil {

    private static final SessionFactory sessionFactory;

    static {
        try {
            // Create the SessionFactory from hibernate.cfg.xml
            sessionFactory = new Configuration().configure().buildSessionFactory();
        } catch (Throwable ex) {
            // Make sure you log the exception, as it might be swallowed
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }

}


DateUtils
public class DateUtils
{
//日期加(天数)
public static java.util.Date addTimeByDay(java.util.Date date,int days) throws Exception
{
Calendar calendar=Calendar.getInstance();  
calendar.setTime(date);
calendar.set(Calendar.DATE,calendar.get(Calendar.DATE)+days);
return calendar.getTime();
}

public static java.util.Date addTimeByMinutes(java.util.Date date,int minutes) throws Exception
{
Calendar calendar=Calendar.getInstance();  
calendar.setTime(date);
calendar.set(Calendar.MINUTE,calendar.get(Calendar.MINUTE)+minutes);
return calendar.getTime();
}

public static java.util.Date addTimeBySeconds(java.util.Date date,int seconds) throws Exception
{
Calendar calendar=Calendar.getInstance();  
calendar.setTime(date);
calendar.set(Calendar.SECOND,calendar.get(Calendar.SECOND)+seconds);
return calendar.getTime();
}

//得到当前日期
public static java.util.Date nowTime() throws Exception
{
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
String datestr = sdf.format(java.util.Calendar.getInstance().getTime());

return sdf.parse(datestr);
}
//得到当前时间
public static java.util.Date nowFullTime() throws Exception
{
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String datestr = sdf.format(java.util.Calendar.getInstance().getTime());
return sdf.parse(datestr);
}

public static java.util.Date nowFullTime(String format) throws Exception
{
SimpleDateFormat sdf = new SimpleDateFormat(format);
String datestr = sdf.format(java.util.Calendar.getInstance().getTime());
return sdf.parse(datestr);
}

public static String convertDateStrToString(String datestr,String format) throws Exception
{
String result = null;
SimpleDateFormat sdf = new SimpleDateFormat(format);
try
{
result = sdf.format(sdf.parse(datestr));
}
catch (Exception ex)
{
sdf = new SimpleDateFormat("yyyy-MM-dd");
result = sdf.format(sdf.parse(datestr));
}
return result;
}

public static String convertDateToString(java.util.Date date,String format) throws Exception
{
SimpleDateFormat sdf = new SimpleDateFormat(format);
return sdf.format(date);
}

public static java.util.Date formatDateStr(String datestr) throws Exception
{
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

return sdf.parse(datestr);
}

public static java.util.Date formatDateStr(String datestr,String format) throws Exception
{
java.util.Date result = null;
SimpleDateFormat sdf = new SimpleDateFormat(format);
try
{
result = sdf.parse(datestr);
}
catch (Exception ex)
{
sdf = new SimpleDateFormat("yyyy-MM-dd");
result = sdf.parse(datestr);
}
return result;
}

public static java.util.Date formatFullDateStr(String datestr) throws Exception
{
java.util.Date result = null;
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
try
{
result = sdf.parse(datestr);
}
catch (Exception ex)
{
sdf = new SimpleDateFormat("yyyy-MM-dd");
result = sdf.parse(datestr);
}
return result;
}
}
    

  NumberUtils
     public class NumberUtils
{
private NumberUtils() {

}
/**
* 精确的加法运算.
*/
public static double add(double v1, double v2) {
BigDecimal b1 = new BigDecimal(v1);
BigDecimal b2 = new BigDecimal(v2);
return b1.add(b2).doubleValue();
}

/**
*
* 精确的减法运算.
*
* @param v1 被减数
* @param v2 减数
*/
public static double subtract(double v1, double v2) {
BigDecimal b1 = new BigDecimal(Double.toString(v1));
BigDecimal b2 = new BigDecimal(Double.toString(v2));
return b1.subtract(b2).doubleValue();
}

/**
* 提供精确的乘法运算.
*/
public static double multiply(double v1, double v2) {
BigDecimal b1 = new BigDecimal(v1);
BigDecimal b2 = new BigDecimal(v2);
return b1.multiply(b2).doubleValue();
}

/**
* 提供精确的乘法运算，并对运算结果截位.
*
* @param scale 运算结果小数后精确的位数
*/
public static double multiply(double v1, double v2,int scale) {
if (scale < 0) {
throw new IllegalArgumentException("The scale must be a positive integer or zero");
}
BigDecimal b1 = new BigDecimal(v1);
BigDecimal b2 = new BigDecimal(v2);
return b1.multiply(b2).setScale(scale,BigDecimal.ROUND_HALF_UP).doubleValue();
}


/**
* 提供（相对）精确的除法运算.
*
* @see #divide(double, double, int)
*/
public static double divide(double v1, double v2) {
BigDecimal b1 = new BigDecimal(v1);
BigDecimal b2 = new BigDecimal(v2);
return b1.divide(b2).doubleValue();
}

/**
* 提供（相对）精确的除法运算.
* 由scale参数指定精度，以后的数字四舍五入.
*
* @param v1 被除数
* @param v2 除数
* @param scale 表示表示需要精确到小数点以后几位
*/
public static double divide(double v1, double v2, int scale) {
if (scale < 0) {
throw new IllegalArgumentException("The scale must be a positive integer or zero");
}

BigDecimal b1 = new BigDecimal(v1);
BigDecimal b2 = new BigDecimal(v2);
return b1.divide(b2, scale, BigDecimal.ROUND_HALF_UP).doubleValue();
}

/**
* 提供精确的小数位四舍五入处理.
*
* @param v 需要四舍五入的数字
* @param scale 小数点后保留几位
*/
public static double round(double v, int scale) {
if (scale < 0) {
throw new IllegalArgumentException("The scale must be a positive integer or zero");
}
BigDecimal b = new BigDecimal(v);
return b.setScale(scale, BigDecimal.ROUND_HALF_UP).doubleValue();
}
}



JdbcUtils
 
public class JdbcUtils {
static{
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (Exception e) {
e.printStackTrace();
}
}


public static Connection getConnection(){

Connection con = null;
try {

con= DriverManager.getConnection(url,name,password));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return con;
}
public static void close(ResultSet rs,PreparedStatement ps , Connection con) {
try {
if(rs!=null)
rs.close();
if(ps!=null)
ps.close();
if(con!=null)
con.close();
} catch (SQLException e) {
e.printStackTrace();
}

}
}

EncodeUtils
 
    public class EncodeUtils {

private static final String DEFAULT_URL_ENCODING = "UTF-8";

/**
* Hex编码.
*/
public static String hexEncode(byte[] input) {
return Hex.encodeHexString(input);
}

/**
* Hex解码.
*/
public static byte[] hexDecode(String input) {
try {
return Hex.decodeHex(input.toCharArray());
} catch (DecoderException e) {
throw new IllegalStateException("Hex Decoder exception", e);
}
}

/**
* Base64编码.
*/
public static String base64Encode(byte[] input) {
return new String(Base64.encodeBase64(input));
}

/**
* Base64编码, URL安全(将Base64中的URL非法字符如+,/=转为其他字符, 见RFC3548).
*/
public static String base64UrlSafeEncode(byte[] input) {
return Base64.encodeBase64URLSafeString(input);
}

/**
* Base64解码.
*/
public static byte[] base64Decode(String input) {
return Base64.decodeBase64(input);
}

/**
* URL 编码, Encode默认为UTF-8.
*/
public static String urlEncode(String input) {
return urlEncode(input, DEFAULT_URL_ENCODING);
}

/**
* URL 编码.
*/
public static String urlEncode(String input, String encoding) {
try {
return URLEncoder.encode(input, encoding);
} catch (UnsupportedEncodingException e) {
throw new IllegalArgumentException("Unsupported Encoding Exception", e);
}
}

/**
* URL 解码, Encode默认为UTF-8.
*/
public static String urlDecode(String input) {
return urlDecode(input, DEFAULT_URL_ENCODING);
}

/**
* URL 解码.
*/
public static String urlDecode(String input, String encoding) {
try {
return URLDecoder.decode(input, encoding);
} catch (UnsupportedEncodingException e) {
throw new IllegalArgumentException("Unsupported Encoding Exception", e);
}
}

/**
* Html 转码.
*/
public static String htmlEscape(String html) {
return StringEscapeUtils.escapeHtml(html);
}

/**
* Html 解码.
*/
public static String htmlUnescape(String htmlEscaped) {
return StringEscapeUtils.unescapeHtml(htmlEscaped);
}

/**
* Xml 转码.
*/
public static String xmlEscape(String xml) {
return StringEscapeUtils.escapeXml(xml);
}

/**
* Xml 解码.
*/
public static String xmlUnescape(String xmlEscaped) {
return StringEscapeUtils.unescapeXml(xmlEscaped);
}
}