彩色验证码

[quote][/quote]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.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;


public class VerifyCodeGenerator {

private static final VerifyCodeGenerator generator = new VerifyCodeGenerator();

private final String ATTRIBUTE_NAME = "verifycode";


private final int WIDTH = 15;


private final int HEIGHT = 22;

private final int CODE_LENGTH =5;

private final String RAND_RANGE = "abcdefghijklmnopqrstuvwxyz"
+ "ABCDEFGHIJKLMNOPQRSTUVWXYZ" + "1234567890" ;

private final char[] CHARS = RAND_RANGE.toCharArray();

private Random random = new Random();

private VerifyCodeGenerator() {

}

public static VerifyCodeGenerator getInstance() {
return generator;
}

private String getRandString() {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < CODE_LENGTH; i++)
sb.append(CHARS[random.nextInt(CHARS.length)]);
return sb.toString();
}

/**
* ��������ɫ
*
* @param ll
* ������ɫֵ����(lower limit)
* @param ul
* ������ɫֵ����(upper limit)
* @return ��ɵ������ɫ����
*/
private Color getRandColor(int ll, int ul) {
if (ll > 255)
ll = 255;
if (ll < 1)
ll = 1;
if (ul > 255)
ul = 255;
if (ul < 1)
ul = 1;
if (ul == ll)
ul = ll + 1;
int r = random.nextInt(ul - ll) + ll;
int g = random.nextInt(ul - ll) + ll;
int b = random.nextInt(ul - ll) + ll;
Color color = new Color(r, g, b);
return color;
}

/**
* ���ָ���ַ��ͼ�����
*
* @param verifyCode
* ��������ӡ������ַ�
* @return ��ɵ�ͼ�����
*/
private BufferedImage getImage(String verifyCode) {

BufferedImage image = new BufferedImage(WIDTH * CODE_LENGTH, HEIGHT,
BufferedImage.TYPE_INT_RGB);

// ��ȡͼ��������
Graphics graphics = image.getGraphics();

// ���ñ���ɫ
graphics.setColor(getRandColor(0,0));
// ��䱳��ɫ
graphics.fillRect(0, 0, WIDTH * 4, HEIGHT);

// ���ñ߿���ɫ
graphics.setColor(new Color(0, 0,0));
// ���߿�
for (int i = 0; i < 2; i++)
graphics.drawRect(i, i, WIDTH * CODE_LENGTH - i * 2 - 1, HEIGHT - i
* 2 - 1);

// ����������������ɫ
graphics.setColor(getRandColor(50, 100));
// ����50���������
for (int i = 0; i < 100; i++) {
int x1 = random.nextInt(WIDTH * CODE_LENGTH - 4) + 2;
int y1 = random.nextInt(HEIGHT - 4) + 2;
int x2 = random.nextInt(WIDTH * CODE_LENGTH - 2 - x1) + x1;
int y2 = y1;
graphics.drawLine(x1, y1, x2, y2);
}

// ��������
graphics.setFont(new Font("Times New Roman", Font.PLAIN, 18));
// ���ַ�
for (int i = 0; i < this.CODE_LENGTH; i++) {
String temp = verifyCode.substring(i, i + 1);
graphics.setColor(getRandColor(100, 255));
graphics.drawString(temp, 13 * i + 6, 16);
}

// ͼ����Ч
graphics.dispose();

return image;
}


public void printImage(HttpServletRequest request,HttpServletResponse response) {
response.setContentType("image/jpeg");
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 2000);

String verifyCode = this.getRandString();
String str = "ssss";
for (int i = 0; i < 10; i++)
str = str + str;
BufferedImage bi = this.getImage(verifyCode);

request.getSession().setAttribute(ATTRIBUTE_NAME, verifyCode);
try {

ServletOutputStream outStream = response.getOutputStream();

JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(outStream);

encoder.encode(bi);

outStream.flush();

outStream.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}

public boolean check(HttpServletRequest request) {
if (((String) request.getParameter(ATTRIBUTE_NAME)).equals((String) request.getSession().getAttribute(ATTRIBUTE_NAME))) {
request.getSession().removeAttribute(ATTRIBUTE_NAME);
return true;
}
return false;
}
}