案例需求
1. 在登錄頁面用戶登錄的時候要查看到驗證碼，如圖所示：
2. 在生成頁面驗證碼圖片的同時，使用session存儲驗證碼
3. 在處理用戶登錄請求的時候，首先校驗驗證碼
4. 校驗通過才能執行登錄操作
案例分析
代碼實現：
1.頁面代碼
|
2. 配置驗證碼servlet
@WebServlet(name = "CheckcodeServlet",urlPatterns = "/checkcode")
public class CheckcodeServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// 創建畫布
int width = 120;
int height = 40;
BufferedImage bufferedImage = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 獲得畫筆
Graphics g = bufferedImage.getGraphics();
// 填充背景顏色
g.setColor(Color.white);
g.fillRect(0, 0, width, height);
// 繪制邊框
g.setColor(Color.red);
g.drawRect(0, 0, width - 1, height - 1);
// 生成隨機字符3. 登錄servlet
// 准備數據
String data =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";
// 准備隨機對象
Random r = new Random();
// 聲明一個變量 保存驗證碼
String code = "";
// 書寫4個隨機字符
for (int i = 0; i < 4; i++) {
// 設置字體
g.setFont(new Font("宋體", Font.BOLD, 28));
// 設置隨機顏色
g.setColor(new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)));
String str = data.charAt(r.nextInt(data.length())) + "";
g.drawString(str, 10 + i * 28, 30);
// 將新的字符 保存到驗證碼中
code = code + str;
}
// 繪制干擾線
for (int i = 0; i < 6; i++) {
// 設置隨機顏色
g.setColor(new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)));
g.drawLine(r.nextInt(width), r.nextInt(height), r.nextInt(width),
r.nextInt(height));
}
// 將驗證碼 打印到控制台
System.out.println(code);
// 將驗證碼放到session中
request.getSession().setAttribute("code_session", code);
// 將畫布顯示在瀏覽器中
ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
3. 登錄servlet
@WebServlet(name = "LoginServlet",urlPatterns = "/login")
public class LoginServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {4. dao：
//用戶請求中的驗證碼獲取
String code = request.getParameter("code");
//獲取session中保存的驗證碼
String code_session =
(String)request.getSession().getAttribute("code_session");
//與session中保存的驗證碼進行校驗
if(!code_session.equalsIgnoreCase(code)){
//驗證碼錯誤，告訴用戶，頁面提示
request.setAttribute("msg","驗證碼錯誤");
request.getRequestDispatcher("/login.jsp").forward(request,response);
return;
}
//驗證碼正確，登錄邏輯執行
//獲取用戶名和密碼
String username = request.getParameter("username");
String password = request.getParameter("password");
//調用Service方法，登錄用戶
UserDao userDao = new UserDao();
User loginUser = userDao.login(username,password);
if(loginUser == null){
request.setAttribute("msg","用戶名或則密碼錯誤");
request.getRequestDispatcher("/login.jsp").forward(request,response);
return;
}else{
//登陸成功，跳轉主頁
response.sendRedirect(request.getContextPath());
return;
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
4. dao：
public class UserDao {
private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());
/**
* 查詢用戶名和密碼是否匹配的方法
*/
@Override
public User login(String username, String password) {
String sql = "select * from user where username = ? and password = ?";
try {
User query = template.queryForObject(sql, new
BeanPropertyRowMapper<User>(User.class), username,password);
return query;
}catch (Exception e){
e.printStackTrace();
return null;
}
}
}
session的與cookie的區別
