java實現驗證碼功能

java實現驗證碼功能

    經過java代碼實現驗證碼功能的通常思路：

1、經過java代碼生成一張驗證碼的圖片，將驗證碼的圖片保存到項目中的指定文件中去，代碼以下：

package com.util;

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.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.Random;

import javax.imageio.ImageIO;

public class VerifyCodeUtils {

	// 使用到Algerian字體，系統裏沒有的話須要安裝字體，字體只顯示大寫，去掉了1,0,i,o幾個容易混淆的字符
	public static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";
	private static Random random = new Random();

	/**
	 * 使用系統默認字符源生成驗證碼
	 * 
	 * @param verifySize
	 *            驗證碼長度
	 * @return
	 */
	public static String generateVerifyCode(int verifySize) {
		return generateVerifyCode(verifySize, VERIFY_CODES);
	}

	/**
	 * 使用指定源生成驗證碼
	 * 
	 * @param verifySize
	 *            驗證碼長度
	 * @param sources
	 *            驗證碼字符源
	 * @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();
	}

	/**
	 * 生成隨機驗證碼文件,並返回驗證碼值
	 * 
	 * @param w
	 * @param h
	 * @param outputFile
	 * @param verifySize
	 * @return
	 * @throws IOException
	 */
	public static String outputVerifyImage(int w, int h, File outputFile, int verifySize) throws IOException {
		String verifyCode = generateVerifyCode(verifySize);
		outputImage(w, h, outputFile, verifyCode);
		return verifyCode;
	}

	/**
	 * 輸出隨機驗證碼圖片流,並返回驗證碼值
	 * 
	 * @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;
	}

	/**
	 * 生成指定驗證碼圖像文件
	 * 
	 * @param w
	 * @param h
	 * @param outputFile
	 * @param code
	 * @throws IOException
	 */
	public static void outputImage(int w, int h, File outputFile, String code) throws IOException {
		if (outputFile == null) {
			return;
		}
		File dir = outputFile.getParentFile();
		if (!dir.exists()) {
			dir.mkdirs();
		}
		try {
			outputFile.createNewFile();
			FileOutputStream fos = new FileOutputStream(outputFile);
			outputImage(w, h, fos, code);
			fos.close();
		} catch (IOException e) {
			throw e;
		}
	}

	/**
	 * 輸出指定驗證碼圖片流
	 * 
	 * @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);// 設置邊框色
		g2.fillRect(0, 0, w, h);

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

		// 繪製干擾線
		Random random = new Random();
		g2.setColor(getRandColor(160, 200));// 設置線條的顏色
		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);
		}

		// 添加噪點
		float yawpRate = 0.05f;// 噪聲率
		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);// 使圖片扭曲

		g2.setColor(getRandColor(100, 160));
		int fontSize = h - 4;
		Font font = new Font("Algerian", 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);
	}

	/**
	 * 經過數值獲取顏色
	 * @param fc
	 * @param bc
	 * @return
	 */
	private static Color getRandColor(int fc, int bc) {
		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);
	}

	/**
	 * 獲取一個隨機的顏色
	 * @return
	 */
	private static int getRandomIntColor() {
		int[] rgb = getRandomRgb();
		int color = 0;
		for (int c : rgb) {
			color = color << 8;
			color = color | c;
		}
		return color;
	}

	/**
	 * 獲取一個隨機的三位數的顏色值
	 * @return
	 */
	private static int[] getRandomRgb() {
		int[] rgb = new int[3];
		for (int i = 0; i < 3; i++) {
			rgb[i] = random.nextInt(255);
		}
		return rgb;
	}

	/**
	 * 使圖片扭曲
	 * @param g
	 * @param w1
	 * @param h1
	 * @param color
	 */
	private static void shear(Graphics g, int w1, int h1, Color color) {
		shearX(g, w1, h1, color);
		shearY(g, w1, h1, color);
	}

	/**
	 * 使圖片X方向扭曲
	 * @param g
	 * @param w1
	 * @param h1
	 * @param color
	 */
	private static void shearX(Graphics g, int w1, int h1, Color color) {

		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);
			}
		}

	}

	/**
	 * 使圖片Y方向扭曲
	 * @param g
	 * @param w1
	 * @param h1
	 * @param color
	 */
	private static void shearY(Graphics g, int w1, int h1, Color color) {

		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);
			}

		}

	}
	
	//生成一張驗證碼圖片，並保存到項目的verifyCodeImg文件夾下
	public static String createOneCodeImage(){
		String imgName = "";
		try {
			File dir = new File("./verifyCodeImg");
			int w = 100, h = 30;
			String verifyCode = generateVerifyCode(4);
			File file = new File(dir, verifyCode + ".jpg");
			outputImage(w, h, file, verifyCode);
			imgName = verifyCode;
		} catch (IOException e) {
			imgName = "";
			e.printStackTrace();
		}finally{
			return imgName;
		}
	}

	public static void main(String[] args) throws IOException {
		
		String codeImage = VerifyCodeUtils.createOneCodeImage();
		System.out.println(codeImage);
	
	}
}

2、將項目中指定文件夾中剛剛生成的驗證碼圖片的路徑在登陸頁面顯示出來，並將生成驗證碼返回的字符串保存在一個字符串變量中，假設保存在變量A中；

3、在用戶登陸時，經過登陸中的輸入框獲取用戶輸入的驗證碼值，保存在一個字符串類型的變量中，假設保存在變量B中；

4、將變量A與變量B經過equals()方法進行比較，若是A.equals(B)那麼用戶輸入的驗證碼正確，不然輸入的驗證碼不正確；