import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.font.FontRenderContext;
import java.awt.font.TextLayout;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.text.AttributedString;
import java.util.Random;
import javax.servlet.ServletException;
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;
public class SimpleCaptcha extends HttpServlet {
private Random generator = new Random();
private final static String SIMPLE_CAPCHA_SESSION_KEY = "SIMPLE_CAPCHA_SESSION_KEY";
private static char[] captchars = new char[] { 'a', 'b', 'c', 'd', 'e',
'2', '3', '4', '5', '6', '7', '8', 'g', 'f', 'y', 'n', 'm', 'n',
'p', 'w', 'x' };
/**
* 產生隨機字體
*
* @return
*/
private Font getFont() {
Random random = new Random();
Font font[] = new Font[5];
font[0] = new Font("Ravie", Font.PLAIN, 45);
font[1] = new Font("Antique Olive Compact", Font.PLAIN, 45);
font[2] = new Font("Forte", Font.PLAIN, 45);
font[3] = new Font("Wide Latin", Font.PLAIN, 40);
font[4] = new Font("Gill Sans Ultra Bold", Font.PLAIN, 45);
return font[random.nextInt(5)];
}
/**
* 隨機產生定義的顏色
*
* @return
*/
private Color getRandColor() {
Random random = new Random();
Color color[] = new Color[10];
color[0] = new Color(32, 158, 25);
color[1] = new Color(218, 42, 19);
color[2] = new Color(31, 75, 208);
return color[random.nextInt(3)];
}
/**
* @see javax.servlet.http.HttpServlet#void
* (javax.servlet.http.HttpServletRequest,
* javax.servlet.http.HttpServletResponse)
*/
public void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
int ImageWidth = 200;
int ImageHeight = 100;
int car = captchars.length - 1;
/**
* 產生隨機字符串
*/
String test = "";
for (int i = 0; i < 4; i++) {
test += captchars[generator.nextInt(car) + 1];
}
/**
* 放放Session
*/
req.getSession().setAttribute(SimpleCaptcha.SIMPLE_CAPCHA_SESSION_KEY,
test);
/**
* 得到輸出流
*/
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(resp
.getOutputStream());
BufferedImage bi = new BufferedImage(ImageWidth + 10, ImageHeight,
BufferedImage.TYPE_BYTE_INDEXED);
Graphics2D graphics = bi.createGraphics();
/**
* 設置背景色
*/
graphics.setColor(Color.white);
graphics.fillRect(0, 0, bi.getWidth(), bi.getHeight());
graphics.setColor(Color.black);
AttributedString attstr = new AttributedString(test);
TextLayout textTl = new TextLayout(test, new Font("Courier", Font.BOLD,
70), new FontRenderContext(null, true, false));
AffineTransform textAt = graphics.getTransform();
graphics.setFont(new Font("Courier", Font.BOLD,70));
graphics.setColor(this.getRandColor());
graphics.drawString(test, 10,70);
// textTl.draw(graphics, 4, 60);
int w = bi.getWidth();
int h = bi.getHeight();
shear(graphics, w, h, Color.white);
// this.drawThickLine(graphics, 0, generator.nextInt(ImageHeight) + 1,
// ImageWidth, generator.nextInt(ImageHeight) + 1, 4, Color.BLACK);
resp.setContentType("image/jpg");
encoder.encode(bi);
}
private void shear(Graphics g, int w1, int h1, Color color) {
shearX(g, w1, h1, color);
shearY(g, w1, h1, color);
}
public void shearX(Graphics g, int w1, int h1, Color color) {
int period = generator.nextInt(2);
boolean borderGap = true;
int frames = 1;
int phase = generator.nextInt(2);
for (int i = 0; i < h1; i++) {
double d = (double) (period >> 1)
* Math.sin((double) i / (double) period
+ (6.2831853071795862D * (double) phase)
/ (double) frames);
g.copyArea(0, i, w1, 1, (int) d, 0);
if (borderGap) {
g.setColor(color);
g.drawLine((int) d, i, 0, i);
g.drawLine((int) d + w1, i, w1, i);
}
}
}
public void shearY(Graphics g, int w1, int h1, Color color) {
int period = generator.nextInt(40) + 10; // 50;
boolean borderGap = true;
int frames = 20;
int phase = 7;
for (int i = 0; i < w1; i++) {
double d = (double) (period >> 1)
* Math.sin((double) i / (double) period
+ (6.2831853071795862D * (double) phase)
/ (double) frames);
g.copyArea(i, 0, 1, h1, 0, (int) d);
if (borderGap) {
g.setColor(color);
g.drawLine(i, (int) d, i, 0);
g.drawLine(i, (int) d + h1, i, h1);
}
}
}
private void drawThickLine(Graphics g, int x1, int y1, int x2, int y2,
int thickness, Color c) {
// The thick line is in fact a filled polygon
g.setColor(c);
int dX = x2 - x1;
int dY = y2 - y1;
// line length
double lineLength = Math.sqrt(dX * dX + dY * dY);
double scale = (double) (thickness) / (2 * lineLength);
// The x and y increments from an endpoint needed to create a
// rectangle
double ddx = -scale * (double) dY;
double ddy = scale * (double) dX;
ddx += (ddx > 0) ? 0.5 : -0.5;
ddy += (ddy > 0) ? 0.5 : -0.5;
int dx = (int) ddx;
int dy = (int) ddy;
// Now we can compute the corner points
int xPoints[] = new int[4];
int yPoints[] = new int[4];
xPoints[0] = x1 + dx;
yPoints[0] = y1 + dy;
xPoints[1] = x1 - dx;
yPoints[1] = y1 - dy;
xPoints[2] = x2 - dx;
yPoints[2] = y2 - dy;
xPoints[3] = x2 + dx;
yPoints[3] = y2 + dy;
g.fillPolygon(xPoints, yPoints, 4);
}
}
posted on 2009-09-01 14:43
SIMONE 閱讀(1532)
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