Java生成验证码功能实例代码

页面上输入验证码是比较常见的一个功能,实现起来也很简单.给大家写一个简单的生成验证码的示例程序,需要的朋友可以借鉴一下.

闲话少续,直接上代码.代码中的注释很详细.

package com.SM_test.utils;
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
  public static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";
  private static Random random = new Random();
  /**
   * 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();
  }
  /**
   * 生成随机验证码文件,并返回验证码值
   * @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;
  }
  /**
   * 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;
  }
  /**
   * 生成指定验证码图像文件
   * @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;
    }
  }
  /**
   * 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, 255);
    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(50, 255));// 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("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.setColor(getRandColor(100, 160));
      g2.drawChars(chars, i, 1, ((w-10) / verifySize) * i + 5, h-(h - (int)(fontSize*0.75))/2);
    }
    g2.dispose();
    ImageIO.write(image, "jpg", os);
  }
  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);
  }
  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() {
    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) {
    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) {
    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);
      }
    }
  }
  public static void main(String[] args) throws IOException{
    File dir = new File("e:/abc");
    int w = 200, h = 80;
    for(int i = 0; i < 50; i++){
      String verifyCode = generateVerifyCode(4);
      File file = new File(dir, verifyCode + ".jpg");
      outputImage(w, h, file, verifyCode);
    }
  }
}  

上面这段代码就能生成一个验证码,略微修改就能生成各种各样的形式,main方法可以测试.

下面为大家写一下如何返回到页面

package com.SM_test.saomiao.constroller;
import java.io.IOException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import com.SM_test.utils.VerifyCodeUtils;
@Controller
public class IndexConstroller {
  @RequestMapping(value = "/index")
  public void index(HttpServletRequest request,HttpServletResponse response) throws IOException{
    response.setHeader("Pragma", "No-cache");
    response.setHeader("Cache-Control", "no-cache");
    response.setDateHeader("Expires", 0);
    response.setContentType("image/jpeg");
    //生成随机字串
    String verifyCode = VerifyCodeUtils.generateVerifyCode(4);
    //存入会话session
    HttpSession session = request.getSession(true);
    session.setAttribute("rand", verifyCode.toLowerCase());
    //生成图片
    int w = 200, h = 80;
    VerifyCodeUtils.outputImage(w, h, response.getOutputStream(), verifyCode);
  }
} 

很简单,用HttpServletResponse 就OK了.

需要显示验证码的地方可以直接用img标签,地址就是该Controller的URL就OK了

以上所述是小编给大家介绍的Java生成验证码功能实例代码，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对我们网站的支持！