function _hyz()//换一张函数JS代码
{
/*
1. 获取<img>元素
2. 给它的src指向/tools/VerifyCodeServlet
*/
var img=document.getElementById("imgVerifyCode");
//需要给出一个参数，这个参数每次都不同，这样才能刷新浏览器缓存！
img.src = "/tools/VerifyCodeServlet?a="+ new Date().getTime();
}
//jsp中代码
验证码:<input type="text" name="verifyCode"/><br>
<img src="/tools/VerifyCodeServlet" id="imgVerifyCode"/>
<a href="javascript:_hyz()">换一张</a><br>
//servlet中使用验证码代码
public String login(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/*
* 校验验证码
* 1.获取表单中的验证码
* 2.获取图片上的文字
*/
String verifyCode =request.getParameter("verifyCode");
//VerifyCodeServlet会把真正的验证码保存到session中
String vcode =(String) request.getSession().getAttribute("vCode");//
System.out.println(vcode+" "+verifyCode);
System.out.println(verifyCode.equalsIgnoreCase(vcode));//不区分大小写比较
return null;
}
//生成验证码的过程JAVA代码
public class VerifyCode {
private int w = 70;
private int h = 35;
private Random r = new Random();
// {"宋体", "华文楷体", "黑体", "华文新魏", "华文隶书", "微软雅黑", "楷体_GB2312"}
private String[] fontNames = {"宋体", "华文楷体", "黑体", "微软雅黑", "楷体_GB2312"};
private String codes = "23456789abcdefghjkmnopqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ";
private Color bgColor = new Color(255, 255, 255);
private String text ;
private Color randomColor () {
int red = r.nextInt(150);
int green = r.nextInt(150);
int blue = r.nextInt(150);
return new Color(red, green, blue);
}
private Font randomFont () {
int index = r.nextInt(fontNames.length);
String fontName = fontNames[index];
int style = r.nextInt(4);
int size = r.nextInt(5) + 24;
return new Font(fontName, style, size);
}
private void drawLine (BufferedImage image) {
int num = 3;
Graphics2D g2 = (Graphics2D)image.getGraphics();
for(int i = 0; i < num; i++) {
int x1 = r.nextInt(w);
int y1 = r.nextInt(h);
int x2 = r.nextInt(w);
int y2 = r.nextInt(h);
g2.setStroke(new BasicStroke(1.5F));
g2.setColor(Color.BLUE);
g2.drawLine(x1, y1, x2, y2);
}
}
private char randomChar () {
int index = r.nextInt(codes.length());
return codes.charAt(index);
}
private BufferedImage createImage () {
BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Graphics2D g2 = (Graphics2D)image.getGraphics();
g2.setColor(this.bgColor);
g2.fillRect(0, 0, w, h);
return image;
}
public BufferedImage getImage () {
BufferedImage image = createImage();
Graphics2D g2 = (Graphics2D)image.getGraphics();
StringBuilder sb = new StringBuilder();
// 向图片中画4个字符
for(int i = 0; i < 4; i++) {
String s = randomChar() + "";
sb.append(s);
float x = i * 1.0F * w / 4;
g2.setFont(randomFont());
g2.setColor(randomColor());
g2.drawString(s, x, h-5);
}
this.text = sb.toString();
drawLine(image);
return image;
}
public String getText () {
return text;
}
public static void output (BufferedImage image, OutputStream out)
throws IOException {
ImageIO.write(image, "JPEG", out);
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
VerifyCode vc = new VerifyCode();
BufferedImage image = vc.getImage();//获取一次性验证码图片
// 该方法必须在getImage()方法之后来调用
// System.out.println(vc.getText());//获取图片上的文本
VerifyCode.output(image, response.getOutputStream());//把图片写到指定流中
// 把文本保存到session中，为LoginServlet验证做准备
request.getSession().setAttribute("vCode", vc.getText());
}