雖然現在現成的東西很多,不過還是要多學學代碼,看看作者怎寫的 :-)
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;
public class AuthImg extends HttpServlet ...{
// 設置圖形驗證碼中字符串的字體和大小
private Font mFont = new Font("Arial Black", Font.PLAIN, 16);
public void init() throws ServletException ...{
super.init();
}
// 生成隨即顏色
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);
}
// 生成服務器響應的service方法
public void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException ...{
// 組織生成頁面內容被緩存,保證每次重新生成隨機驗證碼
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
// 指定 圖形驗證碼大小
int width = 100, height = 8;
// 生成一張新圖片
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 在圖片中繪製內容
Graphics g = image.getGraphics();
Random random = new Random();
g.setColor(getRandColor(200, 250));
g.fillRect(1, 1, width - 1, height - 1);
g.setColor(new Color(102, 102, 102));
g.setFont(mFont);
// 隨即生成線條,讓圖片看起來更加雜亂
g.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++) ...{
int x1 = random.nextInt(width - 1);
int y1 = random.nextInt(height - 1);
int x2 = random.nextInt(6) + 1;
int y2 = random.nextInt(12) + 1;
g.drawLine(x1, y1, x2, y2);
}
// 隨機生成線條,讓圖片看起來更雜亂
for (int i = 0; i < 70; i++) ...{
int x1 = random.nextInt(width - 1);
int y1 = random.nextInt(height - 1);
int x2 = random.nextInt(6) + 1;
int y2 = random.nextInt(12) + 1;
g.drawLine(x1, y1, x2, y2);
}
// 讀取變量,用於保存系統生成的隨機字符串
String sRand = "";
for (int i = 0; i < 6; i++) ...{
// 取得一個隨機生成的字符
String tmp = getRandomChar();
sRand += tmp;
// 將系統隨機生成的字符添加到圖形驗證碼圖片上
g.setColor(new Color(20 + random.nextInt(110), 20 + random
.nextInt(110), 20 + random.nextInt(110)));
g.drawString(tmp, 15 * i + 10, 15);
}
// 取得用戶Session
HttpSession session = request.getSession(true);
// 將系統隨機生成的圖形驗證碼添加到用戶Session中
session.setAttribute("rand", sRand);
g.dispose();
// 輸出圖形驗證碼圖片
ImageIO.write(image, "JPEG", response.getOutputStream());
}
private String getRandomChar() ...{
int rand = (int) Math.round(Math.random() * 2);
long itmp = 0;
char ctmp = '';
// 根據rand的值來決定是生成小寫字母,大寫字母和數字
switch (rand) ...{
// 生成大寫字母
case 1:
itmp = Math.round(Math.random() * 25 + 65);
ctmp = (char) itmp;
return String.valueOf(ctmp);
// 生成小寫字母
case 2:
itmp = Math.round(Math.random() * 25 + 97);
ctmp = (char) itmp;
return String.valueOf(ctmp);
// 生成數字
default:
itmp = Math.round(Math.random() * 9);
return String.valueOf(itmp);
}
}
}