今天按组长要求,实现了前端登录界面验证码生成及识别功能,确保网站的安全性,无聊之余,总结今天的工作内容。下面是部分代码的讲解。
上图为前端代码,img标签里加入src的链接,CheckCodeAction.java为后台验证码的生成和验证。changImg()鼠标点击事件为调用后台CheckCodeAction生成验证码,打印到前端。changImg()事件的实现如下:
public class CheckCodeAction extends HttpServlet {
private Gson gson = new Gson();
private HashMap<String, Object> map;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
HttpSession session = request.getSession();
String checkcode = request.getParameter("checkcode");
String last_yzmcode = (String) session.getAttribute("yzmcode");
map = new HashMap<>();
if (checkcode != null) {
PrintWriter pw = response.getWriter();
if (checkcode.equalsIgnoreCase(last_yzmcode)) {
map.put("result", "OK");
String jstr = gson.toJson(map, HashMap.class);
pw.println(jstr);
return;
} else {
map.put("result", "ERROR");
String jstr = gson.toJson(map, HashMap.class);
pw.println(jstr);
return;
}
}
//告诉客户端,输出的格式
response.setContentType("image/jpeg");
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
int width = 80;
int height = 40;
int lines = 7;
BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics g = img.getGraphics();
//设置背景色
g.setColor(Color.WHITE);
g.fillRect(0, 0, width, height);
//设置字体
g.setFont(new Font("黑体", Font.BOLD, 22));
//随机数字
Random r = new Random(new Date().getTime());
String yzmcode = "";
String str[] = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "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"};
for (int i = 0; i < 4; i++) {
int a = r.nextInt(36);
int y = 20 + r.nextInt(10);//10~30范围内的一个整数,作为y坐标
String s = str[a];
Color c = new Color(r.nextInt(200), r.nextInt(200), r.nextInt(200));
g.setColor(c);
g.drawString("" + s, 5 + i * width / 4, y);
yzmcode += s;
}
//干扰线
for (int i = 0; i < lines; i++) {
Color c = new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255));
g.setColor(c);
g.drawLine(r.nextInt(width), r.nextInt(height), r.nextInt(width), r.nextInt(height));
}
g.dispose();//类似于流中的close()带动flush()---把数据刷到img对象当中
ImageIO.write(img, "JPG", response.getOutputStream());
session.setAttribute("yzmcode", yzmcode);
}
}