Java Implementation Verification Code login

To implement a verification code in Java:

1. Create the entity class for the verification code as follows :

2. Import Java.awt.BasicStroke;
4. Import Java.awt.Color;
6. Import Java.awt.Font;
8. Import Java.awt.Graphics2D;
10. Import Java.awt.image.BufferedImage;
12. Import java.io.IOException;
14. Import Java.io.OutputStream;
16. Import Java.util.Random;
20. Import Javax.imageio.ImageIO;
28. public class Verifycode {
30. /**
32. * Nan accommodating heals scythe?
34. * @author blemish lee Carpenter Å?
36. */
40. private int w = 50;
42. private int h = 25;
44. Private random r = new Random ();
46. Private string[] fontnames = {"Yue ã 綋", "Å bond po 妤 bee 綋", "Hazel Contact 綋", "Atlas Jiang boss 呴 din Daeng", "妤 Bee 綋 _gb2312"};
48. Private String codes = "23456789abcdefghjkmnpqrstuvwxyzABCEFGHIJKLMNPQRSTUVWXYZ";
50. Private color bgColor = new Color (255,255,255);
52. private String text;
56. Private Color Randomcolor () {
58. int red = r.nextint (200);
60. int green = r.nextint (200);
62. int blue = r.nextint (200);
64. return new Color (Red,green,blue);
66. }
70. Private Font Randomfont () {
72. int index = r.nextint (fontnames.length);
74. String fontname = Fontnames[index];
76. int style = r.nextint (4);
78. int size = r.nextint (6) +15;
80. return new Font (fontname,style,size);
82. }
84. private void DrawLine (BufferedImage image) {
86. int num = 3;
88. graphics2d g2 = (graphics2d) image.getgraphics ();
90. for (int i=0;i<num;i++) {
92. int x1 = r.nextint ();
94. int y1 = r.nextint ();
96. int x2 = r.nextint ();
98. int y2 = r.nextint ();
100. G2.setstroke (New Basicstroke (1.5F));
102. G2.setcolor (Color.Blue);
104. G2.drawline (X1,Y1,X2,Y2);
106. }
108. }
110. Private char Randomchar () {
112. int index = r.nextint (codes.length ());
114. Return Codes.charat (index);
116. }
118. Private BufferedImage createimage () {
120. BufferedImage image = new BufferedImage (W,H,BUFFEREDIMAGE.TYPE_INT_RGB);
122. graphics2d g2 = (graphics2d) image.getgraphics ();
124. G2.setcolor (This.bgcolor);
126. G2.fillrect (0, 0, W, h);
128. return image;
130. }
132. Public BufferedImage GetImage () {
134. BufferedImage image = createimage ();
136. graphics2d g2 = (graphics2d) image.getgraphics ();
138. StringBuilder sb = new StringBuilder ();
140. for (int i= 0;i<4;i++) {
142. String s = Randomchar () + "";
144. Sb.append (s);
146. float x = I*1.0F*W/4;
148. G2.setfont (Randomfont ());
150. G2.setcolor (Randomcolor ());
152. G2.drawstring (S, x, h-5);
154. }
156. This.text = sb.tostring ();
158. DrawLine (image);
160. return image;
162. }
164. Public String GetText () {
166. return text;
168. }
170. public static void Output (BufferedImage image,outputstream out) throws ioexception{
172. Imageio.write (Image, "JPEG", out);
174. }
176. }

2. Create a servlet for the verification code

2. Import Java.awt.image.BufferedImage;
4. Import java.io.IOException;
6. Import Java.io.PrintWriter;
8. Import Javax.imageio.ImageIO;
10. Import javax.servlet.ServletException;
12. Import Javax.servlet.annotation.WebServlet;
14. Import Javax.servlet.http.HttpServlet;
16. Import Javax.servlet.http.HttpServletRequest;
18. Import Javax.servlet.http.HttpServletResponse;
20. Import util. Verifycode;
24. @WebServlet ("/verifycodeservlet")
26. public class Verifycodeservlet extends HttpServlet {
30. /**
32. * Servlet
34. * @author Weiqiang
36. */
40. public void doget (HttpServletRequest request, httpservletresponse response)
42. Throws Servletexception, IOException {
46. Verifycode VC = new Verifycode ();
48. Response.setheader ("Cache-control", "No-cache");
50. Response.setcontenttype ("Image/jpeg");
52. BufferedImage bim = vc.getimage ();
54. Imageio.write (BIM, "JPEG", Response.getoutputstream ());
56. String Verifycode = vc.gettext ();
58. Request.getsession (). SetAttribute ("Verifycode", Verifycode);
60. }
64. public void DoPost (HttpServletRequest request, httpservletresponse response)
66. Throws Servletexception, IOException {
68. Doget (request, response);
70. }
72. public void Destroy () {
74. Super.destroy ();
76. }
78. public void Init () throws servletexception{
80. }
84. }
86. 3. Configuring in XML

88. Servlet>
    <servlet-name>VerifyCodeServlet</servlet-name>
    <servlet-class>cn.com.shxt.servlet.VerifyCodeServlet</servlet-class>
    </servlet>
    <servlet-mapping>
    <servlet-name>VerifyCodeServlet</servlet-name>
    <url-pattern>/VerifyCodeServlet</url-pattern>
    </servlet-mapping>

3. Use the following code where you need to use the verification code:

[HTML]View PlainCopy

2. <!--It's not clear what the Refresh function is.
4. <script>
6. function Changeverifycode () {
8. document.getElementById ("Validatecodeimg"). src="verifycodeservlet?t=" +math.random ();
12. }
14. </Script>
16. <!--This is the input box for entering the verification code--
18. <INPUT id=txtsn size=4 name=txtsn>
20. <!--This is the display of the captcha, shown in pictures--
22. <!--Src's road strength is the servlet's way--
23. <img src= "<%=basepath%>verifycodeservlet"  border=0 id= "validatecodeimg"  style= "height: 25px; width: 57px" span class= "tag" >/><a href= "#"  onclick= " Changeverifycode () "> can't see clearly? Change a </a></ td>  

4. The actual effect is as follows

String code = request.getparameter ("code");
String verifycode = (string) request.getsession (). getattribute ("Verifycode");

else if (!code.equals (Verifycode)) {//Login failed
Request.setattribute ("message", "Captcha error");
Request.getrequestdispatcher ("/login.jsp"). Forward (request, response);

The code of the foreground and the verification code in the session are compared to realize the function of verification code.

Java Implementation Verification Code login