package com.identity;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
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.JPEGImageDecoder;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
public class IdentityServlet extends HttpServlet {
public static final char[]CHARS ={'2','3','4','5','6','7','8','9','A','B','C','D','E','F',
'G','H','J','K','L','M','N','P','Q','R','S','T','U','V','W','X','Y','Z'};//不包括難以識別的字符和數字o 0,I 1
public static Random random = new Random();//隨機數
//生成隨機六位字符
public static String getRandomString(){
StringBuffer sb = new StringBuffer();
for(int i=0;i<6;i++){
sb.append(CHARS[random.nextInt(CHARS.length)]);
}
return sb.toString();
}
//生成顏色
public static Color getColor(){
return new Color(random.nextInt(50),random.nextInt(255),random.nextInt(50));
}
//反色
public static Color getReverseColor(Color c){
return new Color(255-c.getRed(),255-c.getGreen(),255-c.getBlue());
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("image/jpeg");
//隨機生成的字符串
String randomString = getRandomString();
request.getSession(true).setAttribute("randomString", randomString);
int width = 100;
int height = 30;
//背景色
Color color = getColor();
//前景色
Color reserver = getReverseColor(color);
//創建一個彩色圖片
BufferedImage bi = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
//獲得繪圖對象
Graphics2D g = bi.createGraphics();
g.setFont(new Font(Font.SANS_SERIF ,Font.BOLD,16));//設置字體
//設置背景色
g.setColor(color);
g.fillRect(0, 0, width, height);//繪製背景
g.setColor(reserver);//設置前景色
g.drawString(randomString, 18, 20);//繪製隨機字符
// for(int i=0, n =random.nextInt(100);i<n;i++){
// g.drawRect(random.nextInt(width), random.nextInt(height), 1, 1);//最多點100個噪音點
// }
//轉化成jpeg格式
ServletOutputStream out = response.getOutputStream();
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);//獲得編碼器
encoder.encode(bi);//對圖片進行編碼
out.flush();//輸出到客戶端
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}
<script type="text/javascript">
function reloadImage(){
document.getElementById('identitfy').src='/sss/servlet/IdentityServlet?ts='+new Date().getTime();
}
</script>
<body>
<img src="/sss/servlet/IdentityServlet" id="identitfy" οnclick="reloadImage()"/>
<input type="button" value="換個圖片" id="btn">
</body>
</html>
