图片验证码生成工具类

1、图片生成工具类

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.geom.Line2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

import javax.imageio.ImageIO;

public class RandomGraphic {

	//字符的高度和宽度，单位为像素
	private int wordHeight = 10;
	private int wordWidth = 15;
	//字符大小
	private int fontSize = 18;
	//最大字符串个数
	private static final int MAX_CHARCOUNT = 16;
	//垂直方向起始位置
	private final int initypos = 5;
	//要生成的字符个数，由工厂方法得到
	private int charCount = 0;
	//颜色数组，绘制字串时随机选择一个
	private static final Color[] CHAR_COLOR = { Color.MAGENTA, Color.ORANGE,
			Color.DARK_GRAY, Color.BLACK, Color.PINK, Color.GREEN };
	//随机数生成器
	private Random r = new Random();
	/**
	 * 生成图像的格式常量，JPEG格式,生成为文件时扩展名为.jpg； 输出到页面时需要设置MIME type 为image/jpeg
	 */
	public static String GRAPHIC_JPEG = "JPEG";
	/**
	 * 生成图像的格式常量，PNG格式,生成为文件时扩展名为.png； 输出到页面时需要设置MIME type 为image/png
	 */
	public static String GRAPHIC_PNG = "PNG";

	//用工厂方法创建对象
	protected RandomGraphic(int charCount) {
		this.charCount = charCount;
	}

	/**
	 * 创建对象的工厂方法
	 * @param charCount 要生成的字符个数，个数在1到16之间
	 * @return 返回RandomGraphic对象实例
	 * @throws Exception 参数charCount错误时抛出
	 */
	public static RandomGraphic createInstance(int charCount) throws Exception {
		if (charCount < 1 || charCount > MAX_CHARCOUNT) {
			throw new Exception("Invalid parameter charCount,charCount should between in 1 and 16");
		}
		return new RandomGraphic(charCount);
	}

	/**
	 * 随机生成一个数字串，并以图像方式绘制，绘制结果输出到流out中
	 * @param graphicFormat 设置生成的图像格式，值为GRAPHIC_JPEG或GRAPHIC_PNG
	 * @param out 图像结果输出流
	 * @return 随机生成的串的值
	 * @throws IOException
	 */
	public String drawNumber(String graphicFormat, OutputStream out)
			throws IOException {
		// 随机生成的串的值
		String charValue = "";
		charValue = randNumber();
		return draw(charValue, graphicFormat, out);
	}

	/**
	 * 随机生成一个字母串，并以图像方式绘制，绘制结果输出到流out中
	 * @param graphicFormat 设置生成的图像格式，值为GRAPHIC_JPEG或GRAPHIC_PNG
	 * @param out 图像结果输出流
	 * @return 随机生成的串的值
	 * @throws IOException
	 */
	public String drawAlpha(String graphicFormat, OutputStream out)
			throws IOException {
		// 随机生成的串的值
		String charValue = "";
		charValue = randAlpha();
		return draw(charValue, graphicFormat, out);
	}

	/**
	 * 以图像方式绘制字符串，绘制结果输出到流out中
	 * @param charValue 要绘制的字符串
	 * @param graphicFormat 设置生成的图像格式，值为GRAPHIC_JPEG或GRAPHIC_PNG
	 * @param out 图像结果输出流
	 * @return 随机生成的串的值
	 * @throws IOException
	 */
	public String draw(String charValue, String graphicFormat, OutputStream out)
			throws IOException {
		// 计算图像的宽度和高度
		int w = (charCount + 2) * wordWidth;
		int h = wordHeight * 3;

		// 创建内存图像区
		BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_3BYTE_BGR);
		Graphics2D g = bi.createGraphics();

		// 设置背景色
		Color backColor = Color.WHITE;
		g.setBackground(backColor);
		g.fillRect(0, 0, w, h);

		// 设置font
		g.setFont(new Font(null, Font.BOLD, fontSize));
		// 绘制charValue,每个字符颜色随机
		for (int i = 0; i < charCount; i++) {
			String c = charValue.substring(i, i + 1);
			Color color = CHAR_COLOR[randomInt(0, CHAR_COLOR.length)];
			g.setColor(color);
			int xpos = (i + 1) * wordWidth;
			// 垂直方向上随机
			int ypos = randomInt(initypos + wordHeight, initypos + wordHeight
					* 2);
			g.drawString(c, xpos, ypos);
		}
		Random random = new Random();
        int x1, y1, x2, y2;
        g.setColor(Color.RED);
        int lineNum=30;
        //添加噪点
        for (int i = 0; i < lineNum; i++) {
        	x1=random.nextInt(w)+wordWidth/2;
            y1=random.nextInt(h)+wordHeight/2;
            x2=x1+1;
            y2=y1+1;
            int color = Integer.valueOf(randomHexStr(6), 16);
            g.setColor(new Color(color));
            g.drawLine(x1, y1, x2, y2);
        }	
        //添加斜线
        g.setColor(Color.RED);
        x1=random.nextInt(w/2);
        y1=random.nextInt(h/2);
        x2=random.nextInt(w);
        y2=random.nextInt(h);
        g.drawLine(x1, y1, x2, y2);
        
        
		g.dispose();
		bi.flush();
		// 输出到流
		ImageIO.write(bi, graphicFormat, out);
		return charValue;
	}
	
	public static String randomHexStr(int len) {
        try {
            StringBuffer result = new StringBuffer();
            for(int i=0;i<len;i++) {
                //随机生成0-15的数值并转换成16进制
                result.append(Integer.toHexString(new Random().nextInt(16)));
            }
            return result.toString().toUpperCase();
        } catch (Exception e) {
            System.out.println("获取16进制字符串异常，返回默认...");
            return "00CCCC";
        }
    }

	
	
	protected String randNumber() {
		String charValue = "";
		// 生成随机数字串
		for (int i = 0; i < charCount; i++) {
			charValue += String.valueOf(randomInt(0, 10));
		}
		return charValue;
	}
    /**
     * 生成随机字符串
     * @return
     */
	public String randAlpha() {
		String charValue = "";
		// 生成随机字母串
		for (int i = 0; i < charCount; i++) {
			char c = (char) (randomInt(65, 90));
			charValue += String.valueOf(c);
		}
		return charValue;
	}

	/**
	 * 返回[from,to)之间的一个随机整数
	 * @param from 起始值
	 * @param to 结束值
	 * @return [from,to)之间的一个随机整数
	 */
	protected int randomInt(int from, int to) {
		// Random r = new Random();
		return from + r.nextInt(to - from);
	}

	/**
	 * @param args
	 * @throws Exception
	 */
	public static void main(String[] args) throws Exception {
		RandomGraphic s = new RandomGraphic(4);
		char c = (char) (s.randomInt(65, 90));
		System.out.println(c);
	}

}

2、后端接口

public class ValidateCodeServlet extends HttpServlet {

	private static final long serialVersionUID = -6816540956945089845L;

	protected void doGet(HttpServletRequest req, HttpServletResponse res)
			throws IOException, ServletException {
		//设置输出内容为图像，格式为jpeg
		res.setContentType("image/jpg");
		res.setHeader("Content-type", "image/jpeg");
		try {
			RandomGraphic r = RandomGraphic.createInstance(4);
			String charValue = Utils.getCharAndNumr(4);
			//将字符串的值保留在session中，便于和用户手工输入的验证码比较
			req.getSession().setAttribute("vipValidateCode", charValue);
			//将内容输出到响应客户端对象的输出流中，生成的图片中包含4个字符
			r.draw(charValue, RandomGraphic.GRAPHIC_JPEG, res.getOutputStream());
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}

3、web.xml配置

<servlet>
    	<servlet-name>ValidateCodeServlet</servlet-name>
    	<servlet-class>com.util.ValidateCodeServlet</servlet-class>
	</servlet>
  	<servlet-mapping>
    	<servlet-name>ValidateCodeServlet</servlet-name>
    	<url-pattern>/ValidateCodeServlet</url-pattern>
	</servlet-mapping>

4、前端调用

$("#scode_img").attr("src", "../ValidateCodeServlet?"+Math.random());