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验证码生成

程序员文章站 2022-03-03 08:33:35
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package sfca.util;

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.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.commons.lang.RandomStringUtils;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

public class VerifyCode extends HttpServlet {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	private int length = 4; // 设置默认生成4个数字

	private int width = 60; // 设置图象宽度

	private int height = 20; // 设置图象高度

	private Font mFont = new Font("Fixedsys", Font.PLAIN, 18); // 设置字体

	/**
	 * Constructor of the object.
	 */
	public VerifyCode() {
		super();
	}

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	private Color getRandColor(int fc, int bc) {// 给定范围获得随机颜色
		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);
	}

	/**
	 * The doGet method of the servlet. <br>
	 * 
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request
	 *            the request send by the client to the server
	 * @param response
	 *            the response send by the server to the client
	 * @throws ServletException
	 *             if an error occurred
	 * @throws IOException
	 *             if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		HttpSession session = request.getSession(false);
		response.setContentType("image/jpeg"); // 必须设置ContentType为image/jpeg
		// 设置页面不缓存
		response.addHeader("pragma", "NO-cache");
		response.addHeader("Cache-Control", "no-cache");
		response.addDateHeader("Expries", 0);

		String sessionName = Utils.dealNull(request.getParameter("type"));
		sessionName = Utils.htmlEncode(sessionName);
		if (sessionName == null || "".equals(sessionName)) {
			sessionName = "smasungsms";
		}

		// 在内存中创建图象

		BufferedImage image = new BufferedImage(width, height,
				BufferedImage.TYPE_INT_RGB); // 设置图片大小的
		// 获取图形上下文
		Graphics g = image.getGraphics();
		g.setColor(getRandColor(200, 250)); // 设置背景色
		g.fillRect(0, 0, width, height);

		// 设定字体
		g.setColor(Color.black); // 设置字体色
		g.setFont(mFont);

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

		// 生成随机类
		Random random = new Random();

		// 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(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);
		}

		// 取随机产生的认证码(4位数字)
		String strRandom = RandomStringUtils.randomAlphanumeric(length)
				.toLowerCase();

		for (int i = 0; i < length; i++) {

			String rand = String.valueOf(strRandom.substring(i, i + 1));

			// 将认证码显示到图象中
			g.setColor(new Color(20 + random.nextInt(110), 20 + random
					.nextInt(110), 20 + random.nextInt(110)));
			// 调用函数出来的颜色相同,可能是因为种子太接近,所以只能直接生成
			g.drawString(rand, 13 * i + 6, 16);
		}

		// 将认证码存入SESSION
		if (session == null)
			session = request.getSession(true);
		
		session.setAttribute(sessionName, strRandom);
		 

		// 图象生效
		g.dispose();
		//response.reset();

		// 输出图象到页面
		//ImageIO.write(image, "JPEG", response.getOutputStream());
		ServletOutputStream responseOutputStream = response.getOutputStream();
		JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(responseOutputStream);
		encoder.encode(image);
		
		//关闭流 
		responseOutputStream.flush();
		responseOutputStream.close();
	}

	/**
	 * The doPost method of the servlet. <br>
	 * 
	 * This method is called when a form has its tag value method equals to
	 * post.
	 * 
	 * @param request
	 *            the request send by the client to the server
	 * @param response
	 *            the response send by the server to the client
	 * @throws ServletException
	 *             if an error occurred
	 * @throws IOException
	 *             if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doGet(request, response);
	}

	/**
	 * Initialization of the servlet. <br>
	 * 
	 * @throws ServletException
	 *             if an error occure
	 */
	public void init() throws ServletException {
		// Put your code here
	}

}