java的图片验证码

1.验证码生成工具类

package cn.bd.jboa.util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.imageio.stream.ImageOutputStream;

public class RandomNumUtil {
    private ByteArrayInputStream image;// 图像
    private String str;// 验证码

    private RandomNumUtil() {
        init();// 初始化属性
    }

    /*
     * 取得RandomNumUtil实例
     */
    public static RandomNumUtil Instance() {
        return new RandomNumUtil();
    }

    /*
     * 取得验证码图片
     */
    public ByteArrayInputStream getImage() {
        return this.image;
    }

    /*
     * 取得图片的验证码
     */
    public String getString() {
        return this.str;
    }

    private void init() {
        // 在内存中创建图象
        int width = 85, height = 20;
        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(200, 250));
        g.fillRect(0, 0, width, height);
        // 设定字体
        g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
        // 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(6位数字)
        String sRand = "";
        for (int i = 0; i < 6; i++) {
            String rand = String.valueOf(random.nextInt(10));
            sRand += rand;
            // 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);
        }
        // 赋值验证码
        this.str = sRand;

        // 图象生效
        g.dispose();
        ByteArrayInputStream input = null;
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        try {
            ImageOutputStream imageOut = ImageIO
                    .createImageOutputStream(output);
            ImageIO.write(image, "JPEG", imageOut);
            imageOut.close();
            input = new ByteArrayInputStream(output.toByteArray());
        } catch (Exception e) {
            System.out.println("验证码图片产生出现错误：" + e.toString());
        }

        this.image = input;/* 赋值图像 */
    }

    /*
     * 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);
    }
}

2.action

package cn.bd.jboa.action;

import java.io.ByteArrayInputStream;
import cn.bd.jboa.util.RandomNumUtil;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;

/**
 * 验证码
 * @author TaoXianXue
 *
 */
public class RandomAction extends ActionSupport {

    private static final long serialVersionUID = 1L;
    private ByteArrayInputStream inputStream;

    // 生成验证码方法
    public String execute() throws Exception {
        RandomNumUtil rdnu = RandomNumUtil.Instance();
        this.setInputStream(rdnu.getImage());/// 取得带有随机字符串的图片
        ActionContext.getContext().getSession().put("random", rdnu.getString());//把验证码放入HttpSession中
        return "random";
    }

    public void setInputStream(ByteArrayInputStream inputStream) {
        this.inputStream = inputStream;
    }

    public ByteArrayInputStream getInputStream() {
        return inputStream;
    }
}

3.struts.xml

    <!-- 验证码操作Action配置 -->
    <package name="random" extends="json-default">
        <!-- Random验证码 -->
        <action name="random" class="randomAction">
            <result type="stream" name="random">
                <param name="contentType">image/jpeg</param>
                <param name="inputName">inputStream</param>
            </result>
        </action>
    </package>

4.jsp页面

 <input type="image" src="random.action" onclick="this.src=this.src+'?'" title="点击图片刷新验证码" />