The java captcha generates the concrete code
- 2020-05-09 18:39:46
- OfStack
For your reference, the example code generated by java verification code is Shared as an example in this article. The details are as follows
package com.gonvan.component.captcha;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/**
* Created by yuerzm on 2016/3/14.
*/
public class CaptchaFactory {
private static final char[] CODE_SEQUENCE = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
.toCharArray();
private static final int DEFAULT_WIDTH = 60;
private static final int DEFAULT_HEIGHT = 20;
private static final int DEFAULT_CODE_LEN = 4;
private static final int DEFAULT_CODE_X = 13;
private static final int DEFAULT_CODE_Y = 16;
private static final int DEFAULT_FONT_SIZE = 18;
private static final String DEFAULT_FONT_FAMILY = "Times New Roman";
private static CaptchaFactory instance = new CaptchaFactory();
private int width = DEFAULT_WIDTH; // picture-defining width
private int height = DEFAULT_HEIGHT; // picture-defining height
private int length = DEFAULT_CODE_LEN; // Define the number of captchas to display on the image
private int xx = DEFAULT_CODE_X; // Define the captcha displayed on the image x coordinates
private int yy = DEFAULT_CODE_Y; // Define the captcha displayed on the image y coordinates
private int fontSize = DEFAULT_FONT_SIZE; // Define the font size to display the captcha on the image
private String fontFamily = DEFAULT_FONT_FAMILY; // Define the number of captchas to display on the image
private CaptchaFactory() {
}
public static CaptchaFactory getInstance() {
return instance;
}
/**
* Configure wide high
*
* @param w
* @param h
* @return
*/
public CaptchaFactory configWidthAndHeight(int w, int h) {
instance.width = w;
instance.height = h;
return instance;
}
/**
* Configuration coordinates
*
* @param x
* @param y
* @return
*/
public CaptchaFactory configXY(int x, int y) {
instance.xx = x;
instance.yy = y;
return instance;
}
/**
* Configure font size
*
* @param fontSize
* @return
*/
public CaptchaFactory configFontSize(int fontSize) {
instance.fontSize = fontSize;
return instance;
}
/**
* Configure the font
*
* @param fontFamily
* @return
*/
public CaptchaFactory configFontSize(String fontFamily) {
instance.fontFamily = fontFamily;
return instance;
}
public void write(HttpServletRequest request, HttpServletResponse response) throws IOException {
// will 4 The numeric captcha is saved to Session In the.
Map captcha = generate();
String randomCode = (String) captcha.get("captchaCode");
BufferedImage buffImg = (BufferedImage) captcha.get("captchaImg");
HttpSession session = request.getSession();
session.setAttribute("code", randomCode);
// Disable image caching.
response.setHeader("Pragma", "no-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
response.setContentType("image/jpeg");
// Output the image to Servlet In the output stream.
ServletOutputStream outputStream = response.getOutputStream();
ImageIO.write(buffImg, "jpeg", outputStream);
outputStream.close();
}
public Map<String, Object> generate() throws IOException {
// Define the image buffer
BufferedImage buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics gd = buffImg.getGraphics();
// Setting the background color
gd.setColor(getRandColor(200, 250));
gd.fillRect(0, 0, width, height);
// Set the font size according to the height of the image.
gd.setFont(new Font(fontFamily, Font.PLAIN, fontSize));
// create 1 Random number generator class
Random random = new Random();
// Randomly generated 40 Interference line, so that the authentication code in the image is not easily detected by other programs.
gd.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++) {
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
gd.drawLine(x, y, x + xl, y + yl);
}
// randomCode Used to save the randomly generated captcha for user authentication after login.
StringBuffer randomCode = new StringBuffer();
int red = 0, green = 0, blue = 0;
// Randomly generated length Captcha.
for (int i = 0; i < length; i++) {
// Get the randomly generated captcha number.
String code = String.valueOf(CODE_SEQUENCE[random.nextInt(36)]);
// Generate a random color component to construct a color value, so that the color value of each number output will be different.
red = random.nextInt(110);
green = random.nextInt(110);
blue = random.nextInt(110);
// Draws the captcha into the image with randomly generated colors.
gd.setColor(new Color(red + 20, green + 20, blue + 20));
gd.drawString(code, i * xx + 6, yy);
// Combine the generated random Numbers in 1 Up.
randomCode.append(code);
}
Map<String, Object> retval = new HashMap<>();
retval.put("captchaCode", randomCode.toString());
retval.put("captchaImg", buffImg);
return retval;
}
/**
* Get a random color for a given range
*
* @param fc
* The minimum value
* @param bc
* The maximum
* @return Color
*/
private Color getRandColor(int fc, int bc) {
Random random = new Random();
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);
}
}
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