java awt 实现简单的验证码图片的生成

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics2D;

import java.awt.image.BufferedImage;

import java.io.File;

import java.io.IOException;

import java.util.Random;

import javax.imageio.ImageIO;

public class BuildingVerification {

public static String getVerification(String saveImagePath){
int width = 70;
int height = 30;

BufferedImage buffImg = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);
Graphics2D g = buffImg.createGraphics();

// 创建一个随机数生成器类
Random random = new Random();

// 设定图像背景色(因为是做背景，所以偏淡)
g.setColor(getRandColor(200, 250));
g.fillRect(0, 0, width, height);

// 设置字体
Font font = new Font("Times New Roman", Font.HANGING_BASELINE, 28);
g.setFont(font);

// 画边框。
g.setColor(Color.BLACK);
g.drawRect(0, 0, width - 1, height - 1);

// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到。
g.setColor(Color.GRAY);
g.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); 
g.drawLine(x, y, x + xl, y + yl); 
} 

// randomCode用于保存随机产生的验证码，以便用户登录后进行验证。
StringBuffer randomCode = new StringBuffer(); 
String code = null;

int length = 4;
String base = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
int size = base.length(); 

for (int i = 0; i < length; i++) {
// 得到随机产生的验证码数字。 
int start = random.nextInt(size); 
String strRand = base.substring(start, start + 1); 
g.setColor(getRandColor(1, 100));
g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110))); 
g.drawString(strRand, 15 * i + 6, 24); 
randomCode.append(strRand);
}

code = randomCode.toString();
g.dispose(); 

File file = new File(saveImagePath);  
   String suffix = saveImagePath.substring(saveImagePath.lastIndexOf('.')+1);  
   try {
ImageIO.write(buffImg, suffix, file);
} catch (IOException e) {
e.printStackTrace();
}  
   
   return code;
}

private static 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);

    }

}