本章介绍一个能生成比较好看的图形验证码类
生成验证码工具类
package com.util; import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.Random; import javax.imageio.ImageIO; public class VerifyCodeUtils { //使用到Algerian字体，系统里没有的话需要安装字体，字体只显示大写，去掉了1,0,i,o几个容易混淆的字符
public static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";
private static Random random = new Random(); /**
* 使用系统默认字符源生成验证码
* @param verifySize 验证码长度
* @return
*/
public static String generateVerifyCode(int verifySize){
return generateVerifyCode(verifySize, VERIFY_CODES);
} /**
* 使用指定源生成验证码
* @param verifySize 验证码长度
* @param sources 验证码字符源
* @return
*/
public static String generateVerifyCode(int verifySize, String sources){
if(sources == null || sources.length() == 0){
sources = VERIFY_CODES;
}
int codesLen = sources.length();
Random rand = new Random(System.currentTimeMillis());
StringBuilder verifyCode = new StringBuilder(verifySize);
for(int i = 0; i < verifySize; i++){
verifyCode.append(sources.charAt(rand.nextInt(codesLen-1)));
}
return verifyCode.toString();
} /**
* 生成随机验证码文件,并返回验证码值
* @param w
* @param h
* @param outputFile
* @param verifySize
* @return
* @throws IOException
*/
public static String outputVerifyImage(int w, int h, File outputFile, int verifySize) throws IOException{
String verifyCode = generateVerifyCode(verifySize);
outputImage(w, h, outputFile, verifyCode);
return verifyCode;
} /**
* 输出随机验证码图片流,并返回验证码值
* @param w
* @param h
* @param os
* @param verifySize
* @return
* @throws IOException
*/
public static String outputVerifyImage(int w, int h, OutputStream os, int verifySize) throws IOException{
String verifyCode = generateVerifyCode(verifySize);
outputImage(w, h, os, verifyCode);
return verifyCode;
} /**
* 生成指定验证码图像文件
* @param w
* @param h
* @param outputFile
* @param code
* @throws IOException
*/
public static void outputImage(int w, int h, File outputFile, String code) throws IOException{
if(outputFile == null){
return;
}
File dir = outputFile.getParentFile();
if(!dir.exists()){
dir.mkdirs();
}
try{
outputFile.createNewFile();
FileOutputStream fos = new FileOutputStream(outputFile);
outputImage(w, h, fos, code);
fos.close();
} catch(IOException e){
throw e;
}
} /**
* 输出指定验证码图片流
* @param w
* @param h
* @param os
* @param code
* @throws IOException
*/
public static void outputImage(int w, int h, OutputStream os, String code) throws IOException{
int verifySize = code.length();
BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Random rand = new Random();
Graphics2D g2 = image.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
Color[] colors = new Color[5];
Color[] colorSpaces = new Color[] { Color.WHITE, Color.CYAN,
Color.GRAY, Color.LIGHT_GRAY, Color.MAGENTA, Color.ORANGE,
Color.PINK, Color.YELLOW };
float[] fractions = new float[colors.length];
for(int i = 0; i < colors.length; i++){
colors[i] = colorSpaces[rand.nextInt(colorSpaces.length)];
fractions[i] = rand.nextFloat();
}
Arrays.sort(fractions); g2.setColor(Color.GRAY);// 设置边框色
g2.fillRect(0, 0, w, h); Color c = getRandColor(200, 250);
g2.setColor(c);// 设置背景色
g2.fillRect(0, 2, w, h-4); //绘制干扰线
Random random = new Random();
g2.setColor(getRandColor(160, 200));// 设置线条的颜色
for (int i = 0; i < 20; i++) {
int x = random.nextInt(w - 1);
int y = random.nextInt(h - 1);
int xl = random.nextInt(6) + 1;
int yl = random.nextInt(12) + 1;
g2.drawLine(x, y, x + xl + 40, y + yl + 20);
} // 添加噪点
float yawpRate = 0.05f;// 噪声率
int area = (int) (yawpRate * w * h);
for (int i = 0; i < area; i++) {
int x = random.nextInt(w);
int y = random.nextInt(h);
int rgb = getRandomIntColor();
image.setRGB(x, y, rgb);
} shear(g2, w, h, c);// 使图片扭曲 g2.setColor(getRandColor(100, 160));
int fontSize = h-4;
Font font = new Font("Algerian", Font.ITALIC, fontSize);
g2.setFont(font);
char[] chars = code.toCharArray();
for(int i = 0; i < verifySize; i++){
AffineTransform affine = new AffineTransform();
affine.setToRotation(Math.PI / 4 * rand.nextDouble() * (rand.nextBoolean() ? 1 : -1), (w / verifySize) * i + fontSize/2, h/2);
g2.setTransform(affine);
g2.drawChars(chars, i, 1, ((w-10) / verifySize) * i + 5, h/2 + fontSize/2 - 10);
} g2.dispose();
ImageIO.write(image, "png", os);
} private static Color getRandColor(int fc, int bc) {
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);
} private static int getRandomIntColor() {
int[] rgb = getRandomRgb();
int color = 0;
for (int c : rgb) {
color = color << 8;
color = color | c;
}
return color;
} private static int[] getRandomRgb() {
int[] rgb = new int[3];
for (int i = 0; i < 3; i++) {
rgb[i] = random.nextInt(255);
}
return rgb;
} private static void shear(Graphics g, int w1, int h1, Color color) {
shearX(g, w1, h1, color);
shearY(g, w1, h1, color);
} private static void shearX(Graphics g, int w1, int h1, Color color) { int period = random.nextInt(2); boolean borderGap = true;
int frames = 1;
int phase = random.nextInt(2); for (int i = 0; i < h1; i++) {
double d = (double) (period >> 1)
* Math.sin((double) i / (double) period
+ (6.2831853071795862D * (double) phase)
/ (double) frames);
g.copyArea(0, i, w1, 1, (int) d, 0);
if (borderGap) {
g.setColor(color);
g.drawLine((int) d, i, 0, i);
g.drawLine((int) d + w1, i, w1, i);
}
} } private static void shearY(Graphics g, int w1, int h1, Color color) { int period = random.nextInt(40) + 10; // 50; boolean borderGap = true;
int frames = 20;
int phase = 7;
for (int i = 0; i < w1; i++) {
double d = (double) (period >> 1)
* Math.sin((double) i / (double) period
+ (6.2831853071795862D * (double) phase)
/ (double) frames);
g.copyArea(i, 0, 1, h1, 0, (int) d);
if (borderGap) {
g.setColor(color);
g.drawLine(i, (int) d, i, 0);
g.drawLine(i, (int) d + h1, i, h1);
} }
}
public static void main(String[] args) throws IOException{
File dir = new File("C:/Users/H__D/Desktop/");
int w = 200, h = 80;
String verifyCode = generateVerifyCode(4);
File file = new File(dir, verifyCode + ".jpg");
outputImage(w, h, file, verifyCode);
}
}
使用图形验证码
1、使用流程
2、服务器端生成验证码servlet
package com.servlet; import java.io.IOException; import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; import com.util.VerifyCodeUtils; public class CreateCodeServlet extends HttpServlet { @Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.setHeader("Pragma", "No-cache");
resp.setHeader("Cache-Control", "no-cache");
resp.setDateHeader("Expires", 0);
resp.setContentType("image/jpeg"); //生成随机字串
String verifyCode = VerifyCodeUtils.generateVerifyCode(4);
//存入会话session
req.getSession().setAttribute("CODE", verifyCode.toLowerCase()); //生成图片
int width = 100;//宽
int height = 40;//高
VerifyCodeUtils.outputImage(width, height, resp.getOutputStream(), verifyCode); } @Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(req, resp);
}
}
3、服务器端验证验证码servlet
package com.servlet; import java.io.IOException; import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; import com.util.VerifyCodeUtils; public class VerifyCodeServlet extends HttpServlet { @Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { String code = req.getParameter("code");
String key = (String) req.getSession().getAttribute("CODE");
if(code != null && code.equalsIgnoreCase(key)){
req.getSession().removeAttribute("CODE");
resp.getWriter().println(true);
}else{
resp.getWriter().println(false);
}
} @Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// TODO Auto-generated method stub
super.doGet(req, resp);
}
}
4、servet的注册，web.xml文件
<?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" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>test-captcha</display-name> <servlet>
<servlet-name>CreateCodeServlet</servlet-name>
<servlet-class>com.servlet.CreateCodeServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CreateCodeServlet</servlet-name>
<url-pattern>/createCode</url-pattern>
</servlet-mapping> <servlet>
<servlet-name>VerifyCodeServlet</servlet-name>
<servlet-class>com.servlet.VerifyCodeServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>VerifyCodeServlet</servlet-name>
<url-pattern>/verifyCode</url-pattern>
</servlet-mapping> <welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
5、前端html文件
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>测试验证码：</h2>
请输入验证码：<input type="text" name="code" /><img id="codeimg" src="${pageContext.request.contextPath }/createCode" onclick="changeImg()"><a href="javascript:void(0);" onclick="changeImg()">看不清，换一张</a>
<button onclick="submit()">提交</button>
<script type="text/javascript"> //改变验证码事件
function changeImg(){
var img = document.getElementById('codeimg');
img.src = "${pageContext.request.contextPath }/createCode?x=" + Math.floor(Math.random()*100)
} //提交验证并验证验证码
function submit(){
var input = document.getElementsByTagName('input')[0]; //ajax提交
var xhr = new XMLHttpRequest(); xhr.onreadystatechange = function(){
if(xhr.readyState == 4 && xhr.status == 200) {
alert(xhr.responseText);
}
} xhr.open('get','${pageContext.request.contextPath }/verifyCode?code=' + input.value);
xhr.send(null); } </script>
</body>
</html>
6、使用浏览器打开页面访问，效果图如下：