相信大家一定都知道验证码的重要性，所以对验证码不做过多介绍。以下是用struts2实现的一个验证码生成程序。
public class CheckCode extends ActionSupport {
private static final long serialVersionUID = 1L;
private static int WIDTH=60;
private static int HEIGHT=20;
public void makeImage() throws IOException{
HttpServletRequest request = ServletActionContext.getRequest ();
HttpSession session=request.getSession();
HttpServletResponse response=ServletActionContext.getResponse();
response.setContentType("image/jpeg");
ServletOutputStream sos=response.getOutputStream();
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
BufferedImage image=new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
Graphics g=image.getGraphics();
char[] rands=generateCheckCode();
drawBackground(g);
drawRands(g,rands);
g.dispose();
ByteArrayOutputStream bos=new ByteArrayOutputStream();
ImageIO.write(image, "JPEG", bos);
byte[] buf=bos.toByteArray();
response.setContentLength(buf.length);
sos.write(buf);
sos.flush();
bos.close();
sos.close();
session.setAttribute("check_code", new String(rands));
}
private void drawRands(Graphics g, char[] rands) {
g.setColor(Color.black);
g.setFont(new Font(null,Font.ITALIC|Font.BOLD,18));
g.drawString(""+rands[0], 1, 17);
g.drawString(""+rands[1], 16, 15);
g.drawString(""+rands[2], 31, 18);
g.drawString(""+rands[3], 46, 16);
}
private void drawBackground(Graphics g) {
g.setColor(Color.WHITE);
g.fillRect(0, 0, WIDTH, HEIGHT);
for(int i=0;i<120;i++){
int x=(int)(Math.random()*WIDTH);
int y=(int)(Math.random()*HEIGHT);
int green=(int)(Math.random()*255);
int red=(int)(Math.random()*255);
int blue=(int)(Math.random()*255);
g.setColor(new Color(red,green,blue));
g.drawOval(x, y, 1,0);
}
}
private char[] generateCheckCode() {
String chars="0123456789abcdefghijklmnopqrstuvwxyz";
char[] rands=new char[4];
for(int i=0;i<4;i++){
int rand=(int)(Math.random()*36);
rands[i]=chars.charAt(rand);
}
return rands;
}
代码比较简单，不做过多赘述。需要说明的是如何在struts.xml里面对这个类进行配置。如下所示：
<action name="image" class="com.shrx.action.Image" method="makeImage"></action>
这里就不需要对result进行配置了，但是要对method进行配置。
最终生成的验证码如下图所示：
