imagecode.java

这是本人曾经在公司里用的,内部开发框架,基于struts+hibernate今天分享给大家

/**
 * 
 */
package cn.bway.servlet;

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

/**
 * @author Kson
 *
 */
public class ImageCode extends HttpServlet {
	
    private static final String CONTENT_TYPE = "image/jpeg";

    private static String ADDCODE_SESSION_NAME = "addcode";

    //Initialize global variables
    public void init() throws ServletException
    {
        ADDCODE_SESSION_NAME = this.getInitParameter("ADDCODE_SESSION_NAME");
        if (ADDCODE_SESSION_NAME == null || ADDCODE_SESSION_NAME.equals("")) {
            ADDCODE_SESSION_NAME = "addcode";
        }
    }

    //Process the HTTP Get request
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws
        ServletException, IOException
    {
        response.setContentType(CONTENT_TYPE);
        //设置页面不缓存
        response.setHeader("Pragma", "No-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);

        // 在内存中创建图象
        int width = 40, height = 14;
        BufferedImage image = new BufferedImage(width, height,
                                                BufferedImage.TYPE_INT_RGB);

        // 获取图形上下文
        Graphics g = image.getGraphics();

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

        // 设定背景色
        g.setColor(getRandColor(240, 250));
        g.fillRect(0, 0, width, height);

        //设定字体
        g.setFont(new Font("Times New Roman", Font.PLAIN, 14));

        // 取随机产生的认证码(4位数字)
        //String rand = request.getParameter("rand");
        //rand = rand.substring(0,rand.indexOf("."));
        String sRand = "";
        for (int i = 0; i < 4; i++) {
            String rand = String.valueOf(random.nextInt(10));
            sRand += rand;
            //不用彩色的，用黑白的
            g.setColor(getRandColor(0, 50));
            g.drawString(rand, 9 * i + 2, 14);
        }

        // 将认证码存入SESSION
        request.getSession().setAttribute(this.ADDCODE_SESSION_NAME, sRand);

        // 图象生效
        g.dispose();

        // 输出图象到页面
        ServletOutputStream out = response.getOutputStream();
        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
        encoder.encode(image);
        out.close();
    }

    //Process the HTTP Post request
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws
        ServletException, IOException
    {
        doGet(request, response);
    }

    //给定范围获得随机颜色
    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);
    }


    //Clean up resources
    public void destroy()
    {
    }
	
}