验证码设计
首先，創建生成驗證碼類：
//需要導入的包 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.util.Random;import javax.imageio.ImageIO; import javax.imageio.stream.ImageOutputStream;//生成具有背景圖像的驗證碼類
public class IdentifyCode {
?private String randCode;
?private ByteArrayInputStream? inputStream;
?//參數：隨機碼個數
?public IdentifyingCode( int?codeNum ) {
??try {
???createRandCode ( codeNum ) ;
??} catch (Exception e) {
???e.printStackTrace();
??}
?
public String getRandCode() {
??return randCode;
?}
?
?public ByteArrayInputStream getInputStream() {
??return inputStream;
?}?
?}
定義createRandCode方法：
private void createRandCode (int codeNum ) throws Exception{//在內存中創建圖象 int width = 15*codeNum;int height = 25; //創建一個不帶透明色的BufferedImage對象BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);//獲取圖形上下文 Graphics g = image.getGraphics();//生成隨機類 Random random = new Random();//設定背景色 g.setColor(getRandColor(200, 250));g.fillRect(0, 0, width, height);//設定字體 g.setFont(new Font("Times New Roman", Font.PLAIN, 20));//隨機產生1000條干擾線，使圖象中的認證碼不易被其它程序探測到
g.setColor(getRandColor(160, 200)); ?//獲取隨機顏色
for (int i = 0; i < 1000; i++) {int x = random.nextInt(width);int y = random.nextInt(height);int xl = random.nextInt(14);int yl = random.nextInt(14);g.drawLine(x, y, x + xl, y + yl);}//定義數字數組int[] number = {56,57,58,59,60,61,62,63,64,65};//定義小寫字母數組int[] lowerAlphabet = {65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90};//定義大字母數組int[] upperAlphabet = {97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122};//取隨機產生的認證碼(codeNum位數字) StringBuilder sRand = new StringBuilder();for (int i = 0; i < codeNum; i++) {char rand;int nowNum = random.nextInt(3);nowNum=0;switch (nowNum) {case 0: {rand = (char) number[random.nextInt(number.length)];break;}case 1: {rand = (char) lowerAlphabet[random.nextInt(lowerAlphabet.length)];break;}case 2: {rand = (char) upperAlphabet[random.nextInt(upperAlphabet.length)];break;}default: {rand =(char) lowerAlphabet[random.nextInt(lowerAlphabet.length)];break;}}sRand.append(rand);// 將認證碼顯示到圖象中g.setColor(new Color(10 + random.nextInt(110), 10 + random.nextInt(110), 10 + random.nextInt(110))); g.drawString(rand+"", 13 * i + 7, 18);}g.dispose();this.randCode=sRand.toString();ByteArrayOutputStream output = new ByteArrayOutputStream();ImageOutputStream imageOut = ImageIO.createImageOutputStream(output);ImageIO.write(image, "JPEG", imageOut);this.inputStream = new ByteArrayInputStream(output.toByteArray());imageOut.close();output.close();}
?/*?
? * 給定范圍獲得隨機顏色?
? */
?
private? Color getRandColor(int fc, int bc) {
??
Random random = new Random();
??
if (fc > 255)
???fc = 255;
??
if (bc > 255)
???bc = 255;
??
int r = fc + random.nextInt(bc - fc);
??
int g = fc + random.nextInt(bc - fc);
??
int b = fc + random.nextInt(bc - fc);
??
return new Color(r, g, b);
?
}
前臺頁面處理：
<!--加載頁面的同時加載隨機碼--><body onload="loadRandCode()">
<form id="login" name="login" method="post">
<table>
<tr>
??????
<td height="27" colspan="2" bordercolor="#666666">
???????
<span class="style8">驗證碼</span>
??????</td>
??????<td width="128" valign="bottom">
???????<input type="text" name="randCode" id="randCode" class="input_css" tabindex="3" maxlength="4"? />
?
??????</td>
??????<td>
???????<span class="STYLE6"> <span class="style7"><img id ="randCodeImg"? οnclick="changeValidateCode(this)"/></span></span>
??????</td>
?????</tr>
????</table>
</form>
</body>
<script type="text/javascript">
??
/**
???*獲取圖形驗證碼
???*/
??? function changeValidateCode(obj) {
? //獲取當前的時間作為參數，無具體意義?
??????var timenow = new Date().getTime();
?
?????obj.src="${pageContext.request.contextPath}/Login_rand.do?d="+timenow;
?
?????? }
?????? //第一次加載
?????? function loadRandCode(){
?????? ?changeValidateCode(document.getElementById("randCodeImg"))
?????? }
? ??/**
???*登錄驗證和請求
???*/
???? function userLogin(){
var webForm = document.getElementById("login");
??? ?webForm.action = "${pageContext.request.contextPath}/Login_login.do";
???? webForm.submit();}
?
</script>
后臺驗證判斷處理：
public String login() {if(!randCode.equalsIgnoreCase((String)session.get("randCode"))){request.setAttribute("error", "驗證碼輸入錯誤!");return INPUT;} }?
?
轉載于:https://www.cnblogs.com/zhangchunxi/archive/2013/03/15/2961007.html
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