import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
/**
* 动态验证码 关键代码
* @author xiaer
*
*/
public class ImageEnsure {
public ImageEnsure() {
}
private char mapTable[]={
'A','B','C','D','E','F',
'G','H','I','J','K','L',
'M','N','P','Q','R',
'S','T','U','V','W','X',
'Y','Z','0','1','2','3',
'4','5','6','7','8','9'};
public String getEnsure(int width, int height, OutputStream os) {
if(width<=0)width=60;
if(height<=0)height=20;
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 获取图形上下文
Graphics g = image.getGraphics();
// 设定背景色
g.setColor(new Color(0xFCF000));
g.fillRect(0, 0, width, height);
//画边框
g.setColor(Color.black);
g.drawRect(0,0,width-1,height-1);
// 取随机产生的认证码
String strEnsure = "";
// 4代表4位验证码
for(int i=0; i<4; ++i) {
strEnsure += mapTable[(int)(mapTable.length*Math.random())];
}
// 将认证码显示到图象中
g.setColor(Color.black);
g.setFont(new Font("Atlantic Inline",Font.PLAIN,18));
String str = strEnsure.substring(0,1);
g.drawString(str,8,17);
str = strEnsure.substring(1,2);
g.drawString(str,20,15);
str = strEnsure.substring(2,3);
g.drawString(str,35,18);
str = strEnsure.substring(3,4);
g.drawString(str,45,15);
// 随机产生50个干扰点
Random rand = new Random();
for (int i=0;i<50;i++)
{
int x = rand.nextInt(width);
int y = rand.nextInt(height);
g.drawOval(x,y,1,1);
}
// 释放图形上下文
g.dispose();
try {
// 输出图象到页面
ImageIO.write(image, "JPEG", os);
} catch (IOException e) {
return "";
}finally{
}
return strEnsure;
}
/*
public static void main(String []args) {
try{
BufferedOutputStream os = new BufferedOutputStream(
new FileOutputStream("c:\\test.jpg"));
new ImageEnsure().getEnsure(100, 200, os);
os.flush();
os.close();
} catch(Exception e) {}
}
*/
}