Java實現登陸驗證碼

登陸驗證碼

Servlet

/*

• 從請求中獲取數據,獲取驗證碼的session的值轉爲String類型,      
• 銷燬,防止返回後驗證碼不刷新,從新驗證成功      
• 判斷驗證碼是否相同(忽略大小寫)  
• 相同:建立user對象調用service層的方法驗證返回結果是否爲空      
   爲空:建立session:儲存錯誤信息,轉發,登陸頁面顯示登陸名或密碼錯誤    
   不爲空:建立session:儲存用戶名,轉發,到登陸成功頁面      
• 不相同:建立session:儲存錯誤信息,登陸頁面顯示驗證碼錯誤(判斷若是session爲null不顯示) 

public class Servlet extends HttpServlet {  
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {      
Login login = new service.impl.Login();   
String username =request.getParameter("username");  
String password = request.getParameter("password");   
String code = request.getParameter("code");        
Object checkcode1 = request.getSession().getAttribute("checkcode");
String checkcode = (String) checkcode1;        
request.getSession().removeAttribute("checkcode");       
 if (checkcode!=null&&code.equalsIgnoreCase(checkcode)){      
User u=new User();            
u.setUsername(username);            
u.setPassword(password);    
User user = login.Login(u);   
if (user!=null){                request.getSession().setAttribute("username",username)         
request.getRequestDispatcher("Success.jsp").forward(request,response);      
}else{                request.getSession().setAttribute("userfail","用戶名或密碼錯誤");               
 request.getRequestDispatcher("index.jsp").forward(request,response);       
}        }else{            request.getSession().setAttribute("codefail","驗證碼錯誤");    
request.getRequestDispatcher("index.jsp").forward(request,response);        
}                   
}

CheckcodeServlet

public class CheckcodeServlet extends HttpServlet {    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {       
//定義驗證碼框的長寬      
int width = 100;     
int height = 50;    
//建立image對象       
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);    
//建立畫筆對象    
Graphics graphics = image.getGraphics();     
//設置畫筆顏色      
graphics.setColor(Color.white);       
//填充背景      
graphics.fillRect(0, 0, width, height);        
//從新設定畫筆顏色        graphics.setColor(Color.BLUE);     
//畫驗證碼的邊框      
graphics.drawRect(0, 0, width - 1, height - 1);    
//將驗證碼所要顯示的內容組成字符串       
String s = "QWERTYUIOPASDFGHJKLZXCVBNMqwertyuiopasdfghjklzxcvbnm1234567890";   
//建立隨機數對象        
Random random = new Random();      
//建立顏色數組       
Color[] colors = {Color.red, Color.BLACK, Color.magenta, Color.YELLOW, Color.GREEN};   
//建立builder對象用於組合驗證碼       
StringBuilder builder = new StringBuilder();    
//for循環畫驗證碼    
for (int i = 1; i <= 4; i++) {         
//每一個字母換一個顏色            graphics.setColor(colors[new Random().nextInt(colors.length)]);     
//隨機生成字符串下標          
int index = random.nextInt(s.length());  
//經過字符串下標拿到字符        
char c = s.charAt(index);       
//組合字符串          
builder.append(c);     
//設置驗證碼的字體       
graphics.setFont(new Font("Comic Sans MS", Font.BOLD, 20));       
//驗證碼所要擺放的位置     
graphics.drawString(c + "", width / 5 * i, height / 2);       
}       
//將驗證碼轉爲String類型      
String s1 = builder.toString();     
//存放在session中        request.getSession().setAttribute("checkcode", s1);        //for循環畫干擾線  
for (int i = 0; i < 30; i++) {         
//設置干擾線顏色         
graphics.setColor(colors[new Random().nextInt(colors.length)]);   
//設置干擾線座標           
int x = random.nextInt(width);    
int y = random.nextInt(height);     
int x1 = random.nextInt(30);       
int y1 = random.nextInt(30);     
int sin = random.nextBoolean() ? 1 : -1;      
int cos = random.nextBoolean() ? 1 : -1;            graphics.drawLine(x, y, x + x1 * sin, y + y1 * cos);        }      
//輸出驗證碼框    
ImageIO.write(image, "jpg", response.getOutputStream());  
}