Java Login Verification Code

First, create a Web project

Use simple servlet to demonstrate Java captcha image generation, servlet simple to use reference http://www.cnblogs.com/ywlaker/p/6038676.html

Second, generate verification code

Create Vcodeobject.java, store verification codes and pictures

Package Com.demo.vcode;import Java.io.inputstream;public class Vcodeobject {private String code;private inputstream in; Public Vcodeobject () {}public-Vcodeobject (String code, InputStream in) {This.code = Code;this.in = in;} Getters & Setters}

Create a Vcode.java to generate a captcha and a picture

Package Com.demo.vcode;import Java.awt.color;import Java.awt.font;import java.awt.graphics;import Java.awt.image.bufferedimage;import Java.io.bytearrayinputstream;import Java.io.bytearrayoutputstream;import Java.io.ioexception;import Java.io.inputstream;import Java.util.random;import Javax.imageio.ImageIO;public class Vcode {public Vcodeobject Create () {//Generate random verification code String code = This.generaterandomverifycode (4);//Generate picture with Captcha BufferedImage img = This.generateimgwithcode (code, InputStream); This.putimginstream (IMG); return new Vcodeobject (code, in);} /** * Randomly generated verification code * * @param length * @return string */private string generaterandomverifycode (int length) {//The length of the verification code that needs to be generated if ( Length <= 0 | | Length >= 8) length = 4;//The range of randomly generated characters string scope = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; StringBuffer code = new StringBuffer (); Random random = new random (), for (int i = 0; i < length; i++) {Code.append (Scope.charat (Random.nextint (62))} return code.tostring ();} /** * Generate a picture with a verification code * * @param code * @param width * @param height * @return bufferedimage */private bufferedimage Generateimgwit Hcode (String code, int width, int height) {bufferedimage img = new BufferedImage (width, Height,bufferedimage.type_int_rgb ); Graphics brush = Img.getgraphics ();//Set Background and border color Brush.setcolor (This.getcolor ()); Brush.fillrect (0, 0, width-1, height-1 ); brush.drawrect (0, 0, width-1, height-1);//write Verification Code Brush.setcolor (This.getcolor ()); Brush.setfont ("Times New R" Oman ", Font.Italic,"); brush.drawstring (Code, 7, 22);//Draw the interfering line//Picture finish, close the resource Brush.dispose (); return img;}  /** * Get random color * * @return color */private color GetColor () {Random random = new Random (); int r = random.nextint (255); int g = Random.nextint (255); int b = Random.nextint (255); return new Color (R, G, b);} /** * Put the picture into the input stream * * @param image * @return InputStream */private inputstream putimginstream (bufferedimage image) {Bytearr Ayoutputstream out = new Bytearrayoutputstream (); try {imageio.write (image, "JPEG", Out);} catch (IOException e) {e.printstacktrace ();} InputStream in = new Bytearrayinputstream (Out.tobytearray ()), return in;}}

Third, the output verification code

Create Demoservlet.java

Package Com.demo.vcode;import Java.io.ioexception;import Java.io.inputstream;import java.io.outputstream;import Javax.servlet.servletconfig;import Javax.servlet.servletexception;import Javax.servlet.http.httpservlet;import Javax.servlet.http.httpservletrequest;import Javax.servlet.http.httpservletresponse;public class DemoServlet Extends HttpServlet {private static final long serialversionuid = 1l;public void init (servletconfig config) throws Servlet Exception {}public void doget (httpservletrequest req, httpservletresponse Res) throws IOException, Servletexception { Res.setcontenttype ("Image/png"); Vcode Vcode = new Vcode (); Vcodeobject vcodeobject = Vcode.create (); InputStream in = Vcodeobject.getin (); Req.getsession (). SetAttribute ("Vcode", Vcodeobject.getcode ()); byte[] bytes = new Byte[1024];int length = 0;try {OutputStream out = Res.getoutputstream (); while ( Length = In.read (bytes))! =-1) {out.write (bytes, 0, length);} In.close (); Out.flush ();} catch (Exception e) {}}public void DoPost (HttpServletRequest req, HttpServletResponse resp) throws IOException, servletexception {}public void Destroy () {}} 

Configure Web. xml

<?xml version= "1.0" encoding= "UTF-8"? ><web-app xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance" xmlns= "Http://java.sun.com/xml/ns/javaee" xmlns:web= "http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi: schemalocation= "Http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version= " 2.5 "><display-name>vcode</display-name><servlet><servlet-name>vcode</ servlet-name><servlet-class>com.demo.vcode.demoservlet</servlet-class></servlet>< Servlet-mapping><servlet-name>vcode</servlet-name><url-pattern>/vcode</url-pattern> </servlet-mapping></web-app>

Browser Address bar Access

Http://127.0.0.1:8080/vcode/vcode

Java Login Verification Code