checkcodeservlet.java

Java购物车及JSTL的应用

package org.qhit.li.store.tool;

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

import javax.imageio.ImageIO;
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;

public class CheckCodeServlet extends HttpServlet {
	/**
	 * 
	 */
	private static final long serialVersionUID = 10;

	private int width = 60;

	private int height = 20;

	public void destroy() {
		super.destroy();
	}

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		HttpSession session = request.getSession();
		response.setContentType("image/jpeg");
		ServletOutputStream sos = response.getOutputStream();

		// 禁止缓存图片,避免生成的图片一致
		response.setHeader("Pragma", "No-cache");
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expires", 0);

		// 内存中构造出图片
		BufferedImage image = new BufferedImage(width, height,
				BufferedImage.TYPE_INT_BGR);
		Graphics g = image.getGraphics();

		// 生成随机验证码
		char[] code = generateCheckCode();
		String code1 = String.valueOf(code).toString();

		session.setAttribute("check_code", code1);
		// 产生图象
		drawBackgroud(g);
		drawRands(g, code);

		// 将图片输出到客户端
		ByteArrayOutputStream bos = new ByteArrayOutputStream();
		ImageIO.write(image, "JPEG", bos);
		byte[] buf = bos.toByteArray();
		response.setContentLength(buf.length);
		sos.write(buf);
		sos.flush();
		sos.close();

	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

	public void init() throws ServletException {

	}

	private char[] generateCheckCode() {
		String codeString = "0123456789abcdefghijklmnopqrstuvwxyz";
		char[] code = new char[4];
		for (int i = 0; i < 4; i++) {
			int rand = (int) (Math.random() * 36);
			code[i] = codeString.charAt(rand);
		}
		return code;
	}

	private void drawBackgroud(Graphics g) {
		g.setColor(new Color(0xDcDcDc));
		g.fillRect(0, 0, width, height);
		// 产生120个干扰点
		for (int i = 0; i < 120; i++) {
			int x = (int) (Math.random() * width);
			int y = (int) (Math.random() * height);
			int red = (int) (Math.random() * 255);
			int green = (int) (Math.random() * 255);
			int blue = (int) (Math.random() * 255);
			g.setColor(new Color(red, green, blue));
			g.drawOval(x, y, 1, 0);
		}
	}

	private void drawRands(Graphics g, char[] code) {
		g.setColor(Color.BLACK);
		g.setFont(new Font(null, Font.ITALIC, 18));
		g.drawString("" + code[0], 1, 17);
		g.drawString("" + code[1], 16, 15);
		g.drawString("" + code[2], 31, 18);
		g.drawString("" + code[3], 46, 16);
		System.out.println("随机码：" + String.valueOf(code));
	}
}