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image validation code generation
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class RandomCodeServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
//驗證碼圖片的寬度
private int width=85;
//驗證碼圖片的高度
private int height=20;
//隨機的字數
private int codeCount=4;
private int x=0;
//字體的高度
private int fontHeight;
private int codeY;
char[] codeSequence = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
public void init() throws ServletException{
//字體寬度
String strWidth=this.getInitParameter("width");
//字體的高度
String strHeight=this.getInitParameter("height");
//字體的字數
String strCodeCount=this.getInitParameter("codeCount");
//逕行判斷
try{
if(strWidth!=null && strWidth.length()!=0){
width=Integer.parseInt(strWidth);
}
if(strHeight!=null && strHeight.length()!=0){
height=Integer.parseInt(strHeight);
}
if(strCodeCount!=null && strCodeCount.length()!=0){
codeCount=Integer.parseInt(strCodeCount);
}
}catch(NumberFormatException e){
e.printStackTrace();
}
x=width/(codeCount+2);
fontHeight=height-2;
codeY=height-4;
}
protected void service(HttpServletRequest req, HttpServletResponse resp)throws ServletException, java.io.IOException {
BufferedImage buffImg = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);
Graphics2D g = buffImg.createGraphics();
//創建一個隨機器生成器類
Random random = new Random();
g.setColor(Color.WHITE);
g.fillRect(0, 0, width, height);
//創建字體,字體的大小隨圖片的高度來定
Font font = new Font("Fixedsys", Font.PLAIN, fontHeight);
//設置字體
g.setFont(font);
//畫邊框
g.setColor(Color.BLACK);
g.drawRect(0, 0, width - 1, height - 1);
//隨機產生160條干擾線,是圖像中的驗證碼不易被其他程序探測到
g.setColor(Color.GRAY);
for(int i = 0; i<160; i++) {
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(1);
int yl = random.nextInt(1);
g.drawLine(x, y, x + xl, y + yl);
}
//randomCodeç用於保存隨機產生的驗證碼,以便於用戶注冊時逕行驗證
StringBuffer randomCode = new StringBuffer();
int red = 0, green = 0, blue = 0;
//隨機產生4位數字的驗證碼
for (int i = 0; i<codeCount; i++) {
//得到隨機產生的驗證碼數字
String strRand = String.valueOf(codeSequence[random.nextInt(36)]);
//產生隨機的顏色分量來構造顏色值,這樣輸出的每位數字的顏色值都將不同
red = random.nextInt(110);
green = random.nextInt(50);
blue = random.nextInt(50);
//用隨機產生的顏色將驗證碼會知道圖像中
g.setColor(new Color(red, green, blue));
g.drawString(strRand, (i + 1) * x, codeY);
//將產生的四個隨機數組合在一起
randomCode.append(strRand);
}
// 將產生的隨機數存貯在session中
HttpSession session = req.getSession();
//resp.addHeader("P3P", "CP=CAO PSA OUR");
//resp.setHeader("P3P","CP='IDC DSP COR ADM DEVi TAIi PSA PSD IVAi IVDi CONi HIS OUR IND CNT'");
session.removeAttribute("validateCode");
session.setAttribute("validateCode", randomCode.toString());
// 禁止圖像緩存
resp.setHeader("Pragma", "no-cache");
resp.setHeader("Cache-Control", "no-cache");
resp.setDateHeader("Expires", 0);
resp.setContentType("image/jpeg");
//將圖像輸出的servlet流中
ServletOutputStream sos = resp.getOutputStream();
ImageIO.write(buffImg, "jpeg", sos);
sos.close();
}
}
@sheldonshen
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sheldonshen commented Sep 13, 2016

generated a random 4 numbers and letters virification code

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