Get the verification code from the server

1. Verification Code Generation Program

Writes the resulting picture to the output stream of the response

Imageio.write (bufferedimage, "JPG", Response.getoutputstream ());

 Packagecom.hdh.content;ImportJava.awt.Color;ImportJava.awt.Font;ImportJava.awt.Graphics;ImportJava.awt.Graphics2D;ImportJava.awt.image.BufferedImage;ImportJava.io.BufferedReader;ImportJava.io.FileReader;Importjava.io.IOException;Importjava.util.ArrayList;Importjava.util.List;ImportJava.util.Random;ImportJavax.imageio.ImageIO;Importjavax.servlet.ServletException;ImportJavax.servlet.http.HttpServlet;Importjavax.servlet.http.HttpServletRequest;ImportJavax.servlet.http.HttpServletResponse;/*** Verification Code Generator * * **/ Public classCheckimgservletextendsHttpServlet {//Save all idioms in the collection    Privatelist<string> words =NewArraylist<string>(); @Override Public voidInit ()throwsservletexception {//initialization phase, read New_words.txt//The absolute disk path must be used to read files in the Web projectString path = Getservletcontext (). Getrealpath ("/web-inf/new_words.txt"); Try{BufferedReader Reader=NewBufferedReader (NewFileReader (path));            String Line;  while(line = Reader.readline ())! =NULL) {Words.add (line);        } reader.close (); } Catch(IOException e) {e.printstacktrace (); }    }     Public voiddoget (httpservletrequest request, httpservletresponse response)throwsservletexception, IOException {//Disable Caching//Response.setheader ("Cache-control", "No-cache"); //Response.setheader ("Pragma", "No-cache"); //Response.setdateheader ("Expires",-1);        intwidth = 120; intHeight = 30; //Step one draw an in-memory pictureBufferedImage BufferedImage =Newbufferedimage (width, height, bufferedimage.type_int_rgb); //Step two picture draw background color---by drawing objectGraphics graphics = Bufferedimage.getgraphics ();//Get Paint Object---brush//You must specify a color before drawing any graphicsGraphics.setcolor (Getrandcolor (200, 250)); Graphics.fillrect (0, 0, width, height); //step three Draw borderGraphics.setcolor (Color.White); Graphics.drawrect (0, 0, width-1, height-1); //Step 44 Random numbersGraphics2D graphics2d =(graphics2d) graphics; //Setting the output fontGraphics2d.setfont (NewFont ("Arial", Font.Bold, 18)); Random Random=NewRandom ();//Generate random numbers        intindex =Random.nextint (Words.size ()); String Word= Words.get (index);//Get Idioms//defining x-Coordinates        intx = 10;  for(inti = 0; I < word.length (); i++) {            //Random ColorGraphics2d.setcolor (NewColor (+ random.nextint (110), 20 +random. Nextint (), + random.nextint (110))); //Rotate -30---30 degrees            intJiaodu = Random.nextint (60)-30; //Conversion radians            Doubletheta = Jiaodu * math.pi/180; //get alpha-numeric            Charc =Word.charat (i); //output C to pictureGraphics2d.rotate (theta, X, 20); Graphics2d.drawstring (String.valueof (c), X,20); Graphics2d.rotate (-theta, X, 20); X+ = 30; }        //save Captcha content to sessionRequest.getsession (). SetAttribute ("Checkcode_session", Word); //Step five draw the interference lineGraphics.setcolor (Getrandcolor (160, 200)); intX1; intx2; intY1; intY2;  for(inti = 0; I < 30; i++) {x1=random.nextint (width); X2= Random.nextint (12); Y1=random.nextint (height); Y2= Random.nextint (12); Graphics.drawline (x1, y1, x1+ x2, x2 +y2); }        //output the above image to the browser ImageIOGraphics.dispose ();//Freeing Resources//write the picture in Response.getoutputstream ()Imageio.write (bufferedimage, "JPG", Response.getoutputstream ()); }     Public voidDoPost (httpservletrequest request, httpservletresponse response)throwsservletexception, IOException {doget (request, response); }    /*** Take a range of color * *@paramFC * int Range parameter 1 *@paramBC * INT Range Parameter 2 *@returnColor*/    PrivateColor Getrandcolor (intFcintBC) {        //take its random colorRandom random =NewRandom (); if(FC > 255) {FC= 255; }        if(BC > 255) {BC= 255; }        intr = FC + random.nextint (BC-FC); intg = FC + random.nextint (BC-FC); intB = fc + random.nextint (BC-FC); return NewColor (R, G, b); }}

2. To a tag through the time parameter in JS when the single-machine verification code constantly refresh the address

<! DOCTYPE html>    function checkimg (obj) {        obj.src= "/web14/checkimg?time" + New Date (). GetTime ();    } </script>        User name: <input type= "text" name= "username" ><br>          Password:<input type= "text" name= "password" >< Br>          Verification Code:<input type= "text" name= "username" > <br>         <input type=" Submit "value=" sign in "><br>    </form></body> 
3. Running Results
 Get the verification code from the server