Java常用工具类(计算MD5，验证码随机生成，天数差值计算)

public final static String calculateMD5(String s) {
     char hexDigits[] = { ‘0‘, ‘1‘, ‘2‘, ‘3‘, ‘4‘, ‘5‘, ‘6‘, ‘7‘, ‘8‘, ‘9‘, ‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘ };
     try {
         byte[] btInput = s.getBytes();
         // 获得MD5摘要算法的 MessageDigest 对象
         MessageDigest mdInst = MessageDigest.getInstance("MD5");
         // 使用指定的字节更新摘要
         mdInst.update(btInput);
         // 获得密文
         byte[] md = mdInst.digest();
         // 把密文转换成十六进制的字符串形式
         int j = md.length;
         char str[] = new char[j * 2];
         int k = 0;
         for (int i = 0; i < j; i++) {
             byte byte0 = md[i];
             str[k++] = hexDigits[byte0 >>> 4 & 0xf];
             str[k++] = hexDigits[byte0 & 0xf];
         }
         return new String(str);
     } catch (Exception e) {
         throw new RuntimeException(e);
     }
 }

public static void main(String []args)
{
String a=calculateMD5("123111111");
System.out.println("a的md5的值是："+a);
}

package t;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class Main1 {

	public static void main(String[] args) {
		String verifyCode = VerifyCodeUtils.generateVerifyCode(4);
		FileOutputStream fos = null;
		try {
			fos = new FileOutputStream("G:\\123.jpg");
			VerifyCodeUtils.outputImage(150, 80, fos, verifyCode);
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			try {
				fos.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}

}

package t;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.Random;
import java.util.concurrent.ThreadLocalRandom;

import javax.imageio.ImageIO;

public class VerifyCodeUtils
{

	// 使用到Algerian字体，系统里没有的话需要安装字体，字体只显示大写，去掉了1,0,i,o几个容易混淆的字符
	//private static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";
	private static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";
	//在这里设置需要生成的代码
	/**
	 * 使用系统默认字符源生成验证码
	 * 
	 * @param verifySize
	 *            验证码长度
	 * @return
	 */
	public static String generateVerifyCode(int verifySize)
	{
		return generateVerifyCode(verifySize, VERIFY_CODES);
	}

	/**
	 * 使用指定源生成验证码
	 * 
	 * @param verifySize
	 *            验证码长度
	 * @param sources
	 *            验证码字符源
	 * @return
	 */
	public static String generateVerifyCode(int verifySize, String sources)
	{
		if (sources == null || sources.length() == 0)
		{
			sources = VERIFY_CODES;
		}
		int codesLen = sources.length();
		Random rand = new Random(System.currentTimeMillis());
		StringBuilder verifyCode = new StringBuilder(verifySize);
		for (int i = 0; i < verifySize; i++)
		{
			verifyCode.append(sources.charAt(rand.nextInt(codesLen - 1)));
		}
		return verifyCode.toString();
	}

	/**
	 * 输出随机验证码图片流,并返回验证码值
	 * 
	 * @param w
	 * @param h
	 * @param os
	 * @param verifySize
	 * @return
	 * @throws IOException
	 */
	public static String outputVerifyImage(int w, int h, OutputStream os, int verifySize) throws IOException
	{
		String verifyCode = generateVerifyCode(verifySize);
		outputImage(w, h, os, verifyCode);
		return verifyCode;
	}

	/**
	 * 输出指定验证码图片流
	 * 
	 * @param w
	 * @param h
	 * @param os
	 * @param code
	 * @throws IOException
	 */
	public static void outputImage(int w, int h, OutputStream os, String code) throws IOException
	{
		int verifySize = code.length();
		BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
		Random rand = new Random();
		Graphics2D g2 = image.createGraphics();
		g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
		Color[] colors = new Color[5];
		Color[] colorSpaces = new Color[] { Color.WHITE, Color.CYAN, Color.GRAY, Color.LIGHT_GRAY, Color.MAGENTA,
				Color.ORANGE, Color.PINK, Color.YELLOW };
		float[] fractions = new float[colors.length];
		for (int i = 0; i < colors.length; i++)
		{
			colors[i] = colorSpaces[rand.nextInt(colorSpaces.length)];
			fractions[i] = rand.nextFloat();
		}
		Arrays.sort(fractions);

		g2.setColor(Color.GRAY);// 设置边框色
		g2.fillRect(0, 0, w, h);

		Color c = getRandColor(200, 250);
		g2.setColor(c);// 设置背景色
		g2.fillRect(0, 2, w, h - 4);

		// 绘制干扰线
		Random random = new Random();
		g2.setColor(getRandColor(160, 200));// 设置线条的颜色
		for (int i = 0; i < 20; i++)
		{
			int x = random.nextInt(w - 1);
			int y = random.nextInt(h - 1);
			int xl = random.nextInt(6) + 1;
			int yl = random.nextInt(12) + 1;
			g2.drawLine(x, y, x + xl + 40, y + yl + 20);
		}

		// 添加噪点
		float yawpRate = 0.05f;// 噪声率
		int area = (int) (yawpRate * w * h);
		for (int i = 0; i < area; i++)
		{
			int x = random.nextInt(w);
			int y = random.nextInt(h);
			int rgb = getRandomIntColor();
			image.setRGB(x, y, rgb);
		}

		shear(g2, w, h, c);// 使图片扭曲

		g2.setColor(getRandColor(100, 160));
		int fontSize = h - 4;
		Font font = new Font("宋体", Font.ITALIC, fontSize);
		g2.setFont(font);
		char[] chars = code.toCharArray();
		for (int i = 0; i < verifySize; i++)
		{
			AffineTransform affine = new AffineTransform();
			affine.setToRotation(Math.PI / 4 * rand.nextDouble() * (rand.nextBoolean() ? 1 : -1),
					(w / verifySize) * i + fontSize / 2, h / 2);
			g2.setTransform(affine);
			g2.drawChars(chars, i, 1, ((w - 10) / verifySize) * i + 5, h / 2 + fontSize / 2 - 10);
		}

		g2.dispose();
		ImageIO.write(image, "jpg", os);
	}

	private static Color getRandColor(int fc, int bc)
	{
		Random random = ThreadLocalRandom.current();
		
		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);
	}

	private static int getRandomIntColor()
	{
		int[] rgb = getRandomRgb();
		int color = 0;
		for (int c : rgb)
		{
			color = color << 8;
			color = color | c;
		}
		return color;
	}

	private static int[] getRandomRgb()
	{
		Random random = ThreadLocalRandom.current();
		int[] rgb = new int[3];
		for (int i = 0; i < 3; i++)
		{
			rgb[i] = random.nextInt(255);
		}
		return rgb;
	}

	private static void shear(Graphics g, int w1, int h1, Color color)
	{
		shearX(g, w1, h1, color);
		shearY(g, w1, h1, color);
	}

	private static void shearX(Graphics g, int w1, int h1, Color color)
	{
		Random random = ThreadLocalRandom.current();
		int period = random.nextInt(2);

		boolean borderGap = true;
		int frames = 1;
		int phase = random.nextInt(2);

		for (int i = 0; i < h1; i++)
		{
			double d = (double) (period >> 1)
					* Math.sin((double) i / (double) period + (6.2831853071795862D * (double) phase) / (double) frames);
			g.copyArea(0, i, w1, 1, (int) d, 0);
			if (borderGap)
			{
				g.setColor(color);
				g.drawLine((int) d, i, 0, i);
				g.drawLine((int) d + w1, i, w1, i);
			}
		}

	}

	private static void shearY(Graphics g, int w1, int h1, Color color)
	{
		Random random = ThreadLocalRandom.current();
		int period = random.nextInt(40) + 10; // 50;

		boolean borderGap = true;
		int frames = 20;
		int phase = 7;
		for (int i = 0; i < w1; i++)
		{
			double d = (double) (period >> 1)
					* Math.sin((double) i / (double) period + (6.2831853071795862D * (double) phase) / (double) frames);
			g.copyArea(i, 0, 1, h1, 0, (int) d);
			if (borderGap)
			{
				g.setColor(color);
				g.drawLine(i, (int) d, i, 0);
				g.drawLine(i, (int) d + h1, i, h1);
			}

		}

	}
}

    //计算两个日期相差天数的绝对值
    public static long calculateApartDays(Date date1, Date date2) {
        //一天对应的毫秒值
        long day = 1000L * 60 * 60 * 24;
        return Math.abs(date1.getTime() / day - date2.getTime() / day);
    }