JavaWeb -- Session应用实例 -- 随机中文验证码 检验

注册页面 login.html

随机中文图片生成Servlet
public class Demo8 extends HttpServlet {
	private static final long serialVersionUID = 1L;
    private static final int width = 120;
    private static final int height = 40;
	
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Demo8() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
		Graphics g = image.getGraphics();
		
		setBackGround(g);
		setBorder(g);
		drawRandomLine(g);
		String random = drawRandomNum((Graphics2D)g);
		request.getSession().setAttribute("checkcode", random);
		response.setContentType("image/jpeg");
		response.setDateHeader("expries", -1);
		response.setHeader("Cache-Control", "no-cache");
		response.setHeader("Pragma", "no-cache");
		ImageIO.write(image, "jpg", response.getOutputStream());
	}

	private String drawRandomNum(Graphics2D g) {
		// TODO Auto-generated method stub
		//[u4e00 ~ u9fa5]
		g.setColor(Color.BLUE);
		g.setFont(new Font(null, Font.BOLD, 20));
		String base = "u7684u4e00u662fu4e86u6211u4e0du4ebau5728u4ed6u6709u8fd9u4e2au4e0au4eecu6765";		
		int x = 5;
		StringBuffer sb = new StringBuffer();
		for(int i=0; i<4; i++)
		{
			String ch = base.charAt(new Random().nextInt(base.length())) + "";
			//System.out.println(ch);
			sb.append(ch);
			int degreen = new Random().nextInt()%30;
			g.rotate(degreen*Math.PI/180, x, 25);
			g.drawString(ch, x, 25);
			g.rotate(-degreen*Math.PI/180, x, 25);
			x += 30;
		}
		return sb.toString();
	}

	private void drawRandomLine(Graphics g) {
		// TODO Auto-generated method stub
		g.setColor(Color.green);
		for(int i=0; i<8; i++)
		{
			int x1 = new Random().nextInt(width);
			int y1 = new Random().nextInt(height);
			int x2 = new Random().nextInt(width);
			int y2 = new Random().nextInt(height);
			g.drawLine(x1, y1, x2, y2);
		}
		
	}

	private void setBorder(Graphics g) {
		// TODO Auto-generated method stub
		g.setColor(Color.blue);
		g.drawRect(1, 1, width-2, height-2);
	}

	private void setBackGround(Graphics g) {
		// TODO Auto-generated method stub
		g.setColor(Color.WHITE);
		g.fillRect(0, 0, width, height);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
	}

}

检验验证码正确性Servlet
public class Demo9 extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Demo9() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		request.setCharacterEncoding("UTF-8");
		response.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=UTF-8");
		PrintWriter out = response.getWriter();
		
		String c_checkcode_temp = request.getParameter("checkcode");
		String c_checkcode = new String(c_checkcode_temp.getBytes("iso8859-1"), "UTF-8"); //防乱码
		String s_checkcode = (String) request.getSession().getAttribute("checkcode");
		out.println("c_code: " + c_checkcode + "s_code: " + s_checkcode);	
		if(c_checkcode!=null && s_checkcode!=null && c_checkcode.equals(s_checkcode))
		{
			out.println("checkcode is right");			
		}
		else
		{
			out.println("checkcode is wrong");
		}
			
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
	}

}