Example tutorial of generating verification code function based on Java

Entering the verification code on the page is a relatively common function, and it is also very simple to implement. I will write a simple sample program for generating verification codes. Friends who need it can learn from it

Entering the verification code on the page Code is a relatively common function, and it is very simple to implement. I will write a simple sample program for generating verification codes. Friends who need it can learn from it.

No further chatter, let’s go directly to the code. In the code The comments are very detailed.

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);  
    }  
  }  
}

The above code can generate a verification code. With slight modifications, it can generate various forms. The main method can be tested.

The following is written for everyone How to return to the page

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);  
  } 
}

is very simple, just use HttpServletResponse.

You can directly use the img tag where you need to display the verification code, and the address is the Controller's The URL is OK

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