生成验证码

[java]代码库

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletResponse;

public class RandImgCreater {
	//默认字符列表
	private static final String CODE_LIST = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";
	//验证码图片高度
	private static final int HEIGHT = 20;
	//默认字符数
	private static final int FONT_NUM = 4;
	//生成验证码图片存放位置
	private HttpServletResponse response;
	//宽度
	private int width = 0;
	//实际字符个数
	private int iNum = 0;
	//实际字符列表
	private String codeList = "";
	//绘制背景
	private boolean drawBgFlag = false;
	//R
	private int rBg = 0;
	//G
	private int gBg = 0;
	//B
	private int bBg = 0;

	//构造函数（自定义存放位置）
	public RandImgCreater(HttpServletResponse response) {
		this.response = response;
		this.width = 13 * FONT_NUM + 12;
		this.iNum = FONT_NUM;
		this.codeList = CODE_LIST;
	}
	//构造函数（自定义存放位置，字符数）
	public RandImgCreater(HttpServletResponse response,int iNum) {
		this.response = response;
		this.width = 13 * iNum + 12;
		this.iNum = iNum;
		this.codeList = CODE_LIST;
	}
	
	//构造函数(自定义存放位置，字符数，字符列表)
	public RandImgCreater(HttpServletResponse response, int iNum,
			String codeList) {
		this.response = response;
		this.width = 13 * iNum + 12;
		this.iNum = iNum;
		this.codeList = codeList;
	}

	//绘制验证码
	public String createRandImage() {
		//1.生成BufferedImage对象，存放图片
		BufferedImage image = new BufferedImage(width, HEIGHT,
				BufferedImage.TYPE_INT_RGB);

		//2.获得BufferedImage对象的画笔
		Graphics g = image.getGraphics();
		
		//生成随机数生成器
		Random random = new Random();

		//开始绘制背景
		if (drawBgFlag) { 
			//设置画笔颜色
			g.setColor(new Color(rBg, gBg, bBg));
			//绘制矩形
			g.fillRect(0, 0, width, HEIGHT);
		} else {
			//设置画笔颜色(随机)
			g.setColor(getRandColor(200, 250));
			//绘制矩形
			g.fillRect(0, 0, width, HEIGHT);
			//循环155次生成随机干扰线条
			for (int i = 0; i < 155; i++) {
//				设置颜色
				g.setColor(getRandColor(140, 200));
				//起始位置x
				int x = random.nextInt(width);
				//起始位置y
				int y = random.nextInt(HEIGHT);
				//结束位置x1
				int xl = random.nextInt(12);
				//结束位置y1
				int yl = random.nextInt(12);
				//绘制线条
				g.drawLine(x, y, x + xl, y + yl);
			}
		}
		//设置画笔字体、样式、大小
		g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
		
		//要返回的字符串
		String sRand = "";
		//循环内随机生成字符
		for (int i = 0; i < iNum; i++) {
			//随机生成字符起始位置
			int rand = random.nextInt(codeList.length());
			//从字符起始位置截取1位字符
			String strRand = codeList.substring(rand, rand + 1);
			//把新生成的字符与旧字符连接(返回用)
			sRand += strRand;
			//设置前景色(字体颜色)
			g.setColor(new Color(20 + random.nextInt(110), 20 + random
					.nextInt(110), 20 + random.nextInt(110)));
			//绘制字符，第一个字符从0位置开始，每个字符相隔13像素
			g.drawString(strRand, 13 * i + 6, 16);
		}
		//释放资源
		g.dispose();
		try {
			//把图片输出到相应位置
			ImageIO.write(image, "JPEG", response.getOutputStream());
		} catch (IOException e) {

		}
		//返回验证码的字符
		return sRand;
	}

	//设置背景色(R,G,B颜色)
	public void setBgColor(int r, int g, int b) {
		drawBgFlag = true;
		this.rBg = r;
		this.gBg = g;
		this.bBg = b;
	}

	//随机生成颜色
	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);
	}
}

[代码运行效果截图]