7.11.1 生成图形验证码

页面：

验证码： <input type='text' value='' name='captcha'/>
<img src="captcha"  alt="看不清楚?请点击刷新" id="captchaImg" style="57px;height:20px;position:relative;left:3px;top:5px" onclick="this.src=this.src+'?'+Math.random();"/>

action 

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.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.imageio.stream.ImageOutputStream;

import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;

import com.opensymphony.xwork2.Action;
import com.opensymphony.xwork2.ActionContext;
import com.yuhong.see.util.Constant;

@Component
@Scope("prototype")
public class CaptchaAction extends BaseAction {

    /**
     * @author JemiYao
     */
    private static final long serialVersionUID = 4103890175141691958L;

    // 输出流
    private ByteArrayInputStream pic;

    // 生成验证图片
    public String execute() {

        int width = 57, height = 20;

        BufferedImage image = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);

        Graphics g = image.getGraphics();

        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 < 4; 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);
        }

        // 将认证码存入SESSION
        ActionContext.getContext().getSession()
                .put(Constant.SESSION_CAPTCHA_KEY, sRand);

        // 图象生效
        g.dispose();
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        ImageOutputStream imageOut;
        try {
            imageOut = ImageIO.createImageOutputStream(output);
            ImageIO.write(image, "JPEG", imageOut);
            imageOut.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

        ByteArrayInputStream input = new ByteArrayInputStream(
                output.toByteArray());
        this.setPic(input);

        return Action.SUCCESS;
    }

    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);
    }

    public ByteArrayInputStream getPic() {
        return pic;
    }

    public void setPic(ByteArrayInputStream pic) {
        this.pic = pic;
    }

}

struts

<action name="captcha" class="captchaAction">
            <result type="stream">
                <param name="contentType">image/jpeg</param>
                <param name="inputName">pic</param>
            </result>
        </action>