java_验证码模块(servlet)
java_验证码模块(servlet)
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.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
@SuppressWarnings("serial" )
public class CheckCodeImage extends HttpServlet {
private Font mFont = new Font( "Arial Black", Font.PLAIN, 16);//字体
/**
* 获得随机颜色
* @param fc 颜色值下限
* @param bc 颜色值上限
* @return
*/
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 void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//取消缓存
response.setHeader( "Pragma", "No-cache" );
response.setHeader( "Cache-Control", "no-cache" );
response.setDateHeader( "Expires", 0);
response.setContentType( "image/jpeg");// 设置响应内容为图片
int width = 58, height = 28;// 图片高度、宽度
BufferedImage image = new BufferedImage(width, height,
BufferedImage. TYPE_INT_RGB);// 构造图片生成器
Graphics g = image.getGraphics(); //构造画板
Random random = new Random();// 随机数生成器
g.setColor(getRandColor(200, 250)); //获得随机颜色
g.fillRect(1, 1, width - 1, height - 1); //填充矩形
g.setColor( new Color(102, 102, 102));
g.drawRect(0, 0, width + 1, height - 1); //绘制矩形的边框
g.setFont( mFont);// 设置字体
g.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++) {//画 155条随机直线
int x = random.nextInt(width - 1);
int y = random.nextInt(height - 1);
int xl = random.nextInt(6) + 1;
int yl = random.nextInt(12) + 1;
g.drawLine(x, y, x + xl, y + yl);
}
for (int i = 0; i < 70; i++) {//画 70条随机直线
int x = random.nextInt(width - 1);
int y = random.nextInt(height - 1);
int xl = random.nextInt(12) + 1;
int yl = random.nextInt(6) + 1;
g.drawLine(x, y, x - xl, y - yl);
}
String sRand = "";
for (int i = 0; i < 4; i++) { //画 4个随机字符串
String tmp = getRandomChar();
sRand += tmp;
g.setColor( new Color(20 + random.nextInt(110), 20 + random
.nextInt(110), 20 + random.nextInt(110)));
g.drawString(tmp, 12 * i + 1, 18); //画随机字符串
}
HttpSession session = request.getSession( true);
session.setAttribute( "checkCodeImage", sRand); // 绑定这个随机字符串到 session
g.dispose(); //释放资源
ImageIO. write(image, "JPEG", response.getOutputStream());
}
private String getRandomChar() { // 获得随机字符串
int rand = (int) Math.round(Math.random() * 2);
long itmp = 0;
char ctmp = '\u0000' ;
switch (rand) {
case 1:
itmp = Math. round(Math.random () * 25 + 65);
ctmp = ( char) itmp;
return String.valueOf(ctmp);
case 2:
itmp = Math. round(Math.random () * 25 + 97);
ctmp = ( char) itmp;
return String.valueOf(ctmp);
default:
itmp = Math. round(Math.random () * 9);
return String.valueOf(itmp);
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}