上一篇实现的是最简单的图片验证，本文要实现复杂一点的：图片是旋转的，并通过一个注册实例把图片验证嵌套在网页中
实现图片旋转功能的代码为：
//写字母
String content = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcedfghijklmnopqrstuvwxyz1234567890";
Random random = new Random();
Graphics2D graphics2D = (Graphics2D)graphics;
//设置字体颜色
graphics2D.setColor(Color.red);
//设置字体及大小
graphics2D.setFont(new Font("宋体", Font.BOLD, 20));
int x=20;
int y=20;
for(int i = 0; i < 4; i++)
{
int index = random.nextInt(content.length());
char letter = content.charAt(index);
double jiaodu = random.nextInt(60)-30;
double theta = jiaodu/360*2*Math.PI;
graphics2D.rotate(theta, x, y);
graphics2D.drawString(letter+" ", x, y);
graphics2D.rotate(-theta, x, y);
x = x+20;
}package com.lsgjzhuwei.servlet.response;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class VerificationCode
*/
@WebServlet(asyncSupported = true, urlPatterns = { "/VerificationCode" })
public class VerificationCode extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public VerificationCode() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
int width = 120;
int height = 30;
//创建一张内存中的缓存图片
BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
///背景色
//通过graphics绘制图像
Graphics graphics = bufferedImage.getGraphics();
//设置颜色
graphics.setColor(Color.yellow);
//填充
graphics.fillRect(0, 0, width, height);
///画边框
graphics.setColor(Color.blue);
graphics.drawRect(0, 0, width-1, height-1);
//写字母
String content = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcedfghijklmnopqrstuvwxyz1234567890";
Random random = new Random();
Graphics2D graphics2D = (Graphics2D)graphics;
//设置字体颜色
graphics2D.setColor(Color.red);
//设置字体及大小
graphics2D.setFont(new Font("宋体", Font.BOLD, 20));
int x=20;
int y=20;
for(int i = 0; i < 4; i++)
{
int index = random.nextInt(content.length());
char letter = content.charAt(index);
double jiaodu = random.nextInt(60)-30;
double theta = jiaodu/360*2*Math.PI;
graphics2D.rotate(theta, x, y);
graphics2D.drawString(letter+" ", x, y);
graphics2D.rotate(-theta, x, y);
x = x+20;
}
//绘制干扰线
int x1;
int x2;
int y1;
int y2;
graphics.setColor(Color.LIGHT_GRAY);
for(int i = 0;i <50;i++)
{
x1=random.nextInt(width);
x2=random.nextInt(width);
y1=random.nextInt(height);
y2=random.nextInt(height);
graphics.drawLine(x1, y1, x2, y2);
}
//将图片输出到浏览器
//将内存的图片通过浏览器输出流输出成jpg图片
ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
}
下面是新建HTML页面，并添加简单的注册按钮，源码如下：
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Insert title here</title> </head> <body> <form> 输入用户名<input type="text"/><br/> 请输入密码<input type="password"/><br/> 请输入验证码<input type="text" name ="checkcode"> <img src="/day06/VerificationCode"/> <br/> <input type="submit" value="注册"/> </form> </body> </html>
下面实现复杂点的功能：单击图片验证码的时候验证码刷新
修改HTML页面代码如下：
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<script type="text/javascript">
function change()
{
//alert("1");
//重新加载生成图片
document.getElementById("myimg").src="/day06/VerificationCode?"+new Date().getTime();
//alert(document.getElementById("myimg").src);
}
</script>
<title>Insert title here</title>
</head>
<body>
<form>
输入用户名<input type="text"/><br/>
请输入密码<input type="password"/><br/>
请输入验证码<input type="text" name ="checkcode">
<img src="/day06/VerificationCode" onclick="change()" id="myimg" style="cursor:pointer"/> <br/>
<input type="submit" value="注册"/>
</form>
</body>
</html>
原文地址：http://blog.csdn.net/longshengguoji/article/details/39449303
