验证码图片生成

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;


/**
 * 验证码生成
 * @author hzp
 *
 */

@Results({ 
    @Result( type="stream",params={"contentType","image/jpeg","inputName","inputStream"})
})
public class ValidateCodeAction extends ActionSupport{
	
	private ByteArrayInputStream inputStream;
	
	// 设置备选验证码:包括"a-z"和数字"0-9"
	private static final String STR = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; 
	private static final int WIDTH = 120;// 验证码图片宽度
	private static final int HEIGTH = 50;// 验证码图片高度
	private static final int LENGTH = 4; // 设置默认生成4个验证码
	private static final String SESSION_NAME = "validateCode";//sesion中的名字
	
	
	public String execute() throws Exception{
		BufferedImage image = new BufferedImage(WIDTH, HEIGTH,BufferedImage.TYPE_3BYTE_BGR);
		Graphics g = image.getGraphics();
		Random random = new Random();// 创建一个随机类
		g.setColor(getRandColor(200, 250));// 背景颜色要偏淡
		g.fillRect(0, 0, WIDTH, HEIGTH);// 画背景
		g.setColor(getRandColor(0, 255));// 边框颜色
		g.drawRect(0, 0, WIDTH - 1, HEIGTH - 1);// 画边框
		g.setColor(getRandColor(160, 200));// 随机产生5条干扰线，使图象中的认证码不易被其它程序探测到
		for (int i = 0; i < 8; i++) {
			int x = random.nextInt(WIDTH);
			int y = random.nextInt(HEIGTH);
			int x1 = random.nextInt(WIDTH);
			int y1 = random.nextInt(HEIGTH);
			g.drawLine(x, y, x1, y1);
		}
		g.setColor(getRandColor(160, 200));// 随机产生100点，使图象中的认证码不易被其它程序探测到
		for (int i = 0; i < 100; i++) {
			int x = random.nextInt(WIDTH);
			int y = random.nextInt(HEIGTH);
			g.drawLine(x, y, x, y);
		}
		Font font = new Font("Times New Roman", Font.ITALIC, 38); // 创建字体，字体的大小应该根据图片的高度来定。
		g.setFont(font);// 设置字体
		
		String sRand = "";

		// 用随机产生的颜色将验证码绘制到图像中。
		// 生成随机颜色(因为是做前景，所以偏深)
		// 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.setColor(new Color(20 + random.nextInt(110),
				20 + random.nextInt(110), 20 + random.nextInt(110)));
		for (int i = 0; i < LENGTH; i++) {
			String ch = String.valueOf(STR.charAt(random.nextInt(STR.length())));
			sRand += ch;
			g.drawString(ch, 22 * i + 12, (random.nextInt(5) - 2) * i + 40);
		}
		// 将生成的字符串存储在session中
		ActionContext.getContext().getSession().put(SESSION_NAME, sRand);
		g.dispose();// 图像生效
		
		
		
		ByteArrayOutputStream output = new ByteArrayOutputStream();
        ImageOutputStream imageOut = ImageIO.createImageOutputStream(output);
        ImageIO.write(image, "JPEG", imageOut);
        imageOut.close();
        ByteArrayInputStream input = new ByteArrayInputStream(output.toByteArray());
        this.setInputStream(input);
		
		
		/*// 禁止图像缓存
		response.setHeader("Pragma", "No-cache");
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expires", 0);
		response.setContentType("image/jpeg");
		// 创建二进制的输出流
		ServletOutputStream sos = response.getOutputStream();
		// 将图像输出到Servlet输出流中。
		ImageIO.write(image, "jpeg", sos);
		sos.flush();
		sos.close();*/
        
		return SUCCESS;
	}
	
	/*
	 * 给定范围获得随机颜色
	 */
	public Color getRandColor(int lower, int upper) {
		Random random = new Random();
		if (upper > 255)
			upper = 255;
		if (upper < 1)
			upper = 1;
		if (lower < 1)
			lower = 1;
		if (lower > 255)
			lower = 255;
		int r = lower + random.nextInt(upper - lower);
		int g = lower + random.nextInt(upper - lower);
		int b = lower + random.nextInt(upper - lower);
		return new Color(r, g, b);
	}
	

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


}