Servlet 页面跳转并弹出提示对话框

ゝ一世哀愁。 2023-10-16 21:24 54阅读 0赞

<pre name="code" class="html">简单的登录验证模块
    点击登录进入相应的Servlet，Servlet调用bean验证用户名是否存在
    如果存在则登录成功，跳转
    如果不存在则弹出错误对话框，并回到登录页面
    开始用的下面两句话
    out.print("<script language='javascript'>alert('the name doesnot exit')</script>");
    response.sendRedirect("Login.jsp");
    但不会显示对话框，而是直接回到Login.jsp
    后来改用
    JOptionPane.showMessageDialog(null, "name doesnot exits");
    response.sendRedirect("Login.jsp");
    则可以实现。

@Override
    	public void doGet(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    			// TODO Auto-generated method stub
    			request.setCharacterEncoding("utf-8"); 
    			response.setCharacterEncoding("utf-8"); 
    		    String username=request.getParameter("username");
    		    String password=request.getParameter("password");
    		    String code=request.getParameter("code");
    		    //状态码（0：默认值（用户未登入成功），1:用户登入成功,2:验证码通过）
    		    String message="0";
    		    boolean target=false;
    		    if(username.equals("")){
    		    	username="0";
    			}
    		    if(password.equals("")){
    		    	password="0";
    		    }
    		    
    		    HttpSession sessions = request.getSession();		    
    		    if(sessions.getAttribute("safecode")!=null ){
    		    	target=true;
    		    	message="2";
    		    }
    		    
    		    if(target){
    		    	 String sql="select * from userinfo info where info.`username`='"+username.trim()+"' and info.`password`='"+password.trim()+"'";
    				    try {
    						ResultSet rusultset=DataBase.select(sql);
    						while(rusultset.next()){
    							message="1";
    							HttpSession session = request.getSession();
    							session.setAttribute("username",username);
    						}
    						DataBase.closeAll(rusultset);				
    					} catch (Exception e) {
    						// TODO Auto-generated catch block
    						e.printStackTrace();
    					}
    		    	
    		    }
    		    
    		   
    		<span style="color:#ff0000;">	
    		    response.setContentType("text/;html");
    	        PrintWriter out=response.getWriter();	
    		    //登入信息返回
    		    if(message.equals("0")){//默认
    		    		JOptionPane.showMessageDialog(null, "用户名或密码不正确");	
    				  response.sendRedirect("./login.html");   
    			  }else if(message.equals("1")){//成功
    				  response.sendRedirect("./message.html");  
    			  }else if(message.equals("2")){//用户名已经存在
    				  JOptionPane.showMessageDialog(null, "注册码不正确");	
    				  response.sendRedirect("./login.html");  
    			  }else{//特殊情况
    				  JOptionPane.showMessageDialog(null, "用户名或密码不正确");	
    				  response.sendRedirect("./login.html");   
    			  }
    		    
    		    out.flush();
    	        out.close();</span>
    		    
    		    
    		
    	}
    
    	@Override
    	public void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		// TODO Auto-generated method stub
    		this.doGet(request, response);
    		
    	}