java web 验证码生成

先看看效果图：





一般需求应该够用了，有线条干扰线，斑点，字体小幅度的旋转。。

还没有与session挂钩上，所以只能用于简单的测试用例。

直接上代码，看代码注释。。。

package com.act262.demo;

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.io.OutputStream;
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;

import sun.java2d.loops.DrawLine;

/**
* 输出随机的验证码
*/
@WebServlet({ "/CheckCode", "/checkCode.do" })
public class CheckCodeServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

/* 宽度 */
private final int WIDTH = 100;
/* 高度 */
private final int HEIGHT = 20;
/* 生成验证码的个数 */
private final int COUNT = 4;
/* 干扰线条数 */
private final int LINE_ROW = 6;

/* 输出的基本码表，如果使用中文，则使用utf-8的码表，类似 \ue234 ，而且应该使用常用字，避免出现偏僻字 */
private final char[] BASECODE = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h',
'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u',
'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U',
'V', 'W', 'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9' };
/* 随机数发生器 */
private Random random;
private BufferedImage image;

// 写出数据
private void write(OutputStream output) throws IOException {
random = new Random();

image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
Graphics graphics = image.getGraphics();

setBackground(graphics);
drawBorder(graphics);
drawDot(graphics);
drawLine(graphics);
drawString(graphics);

ImageIO.write(image, "jpg", output);
}

//写字
private void drawString(Graphics graphics) {
StringBuffer sb = new StringBuffer();
Font font = new Font("宋体", Font.BOLD, 18);
graphics.setFont(font);
graphics.setColor(Color.BLACK);

for (int i = 0; i < COUNT; i++) {
String ch = String
.valueOf(BASECODE[random.nextInt(BASECODE.length)]);
sb.append(ch);

// 设置位置
int x = i * 20 + random.nextInt(12) + 10;
int y = random.nextInt(HEIGHT / 3) + 12;

// 旋转字体
double theta = Math.PI / 180 * random.nextInt(20);
// rotate(graphics, theta);

graphics.drawString(ch, x, y);

// 恢复。。
// rotate(graphics, -theta);
}

System.out.println("验证码：" + sb.toString());
}

//旋转
private void rotate(Graphics graphics, double theta) {
((Graphics2D) graphics).rotate(theta);
}

// 画随机线条
private void drawLine(Graphics graphics) {
for (int i = 0; i < LINE_ROW; i++) {
int x1 = random.nextInt(WIDTH);
int y1 = random.nextInt(HEIGHT);
int x2 = random.nextInt(WIDTH);
int y2 = random.nextInt(HEIGHT);
setRandomColor(graphics);
graphics.drawLine(x1, y1, x2, y2);
}
}

// 画斑点
private void drawDot(Graphics graphics) {
graphics.setColor(Color.red);
for (int i = 0; i < WIDTH; i++) {
int x = i;
int y = random.nextInt(HEIGHT);
int r = random.nextInt(2);
// graphics.fillOval(x, y, r, r);
graphics.drawOval(x, y, r, r);
}
}

// 画边框
private void drawBorder(Graphics graphics) {
graphics.setColor(Color.BLACK);
graphics.drawRect(1, 1, WIDTH - 2, HEIGHT - 2);
}

// 设置背景
private void setBackground(Graphics graphics) {
graphics.setColor(Color.WHITE);
graphics.fillRect(0, 0, WIDTH, HEIGHT);// 填充背景色
}

// 设置随机的画笔颜色
private void setRandomColor(Graphics g) {
g.setColor(new Color(random.nextInt(255), random.nextInt(255), random
.nextInt(255)));
}

protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {

response.setContentType("image/jpeg");
response.setHeader("Expires", "-1");
response.setHeader("Cache-Control", "no-cache");

// 写出数据
write(response.getOutputStream());

}

protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}

}

不足的是，这个验证码数量与字体大小还有图片的大小之间的关系比较难搞，我是一点一点计算调试出来的，有些时候图片上的字体会跑位，这就是画图的难点了。如果修改了数量，字体大小，这些位置关系得重新计算才行。

后续修改

还是這个验证码

package com.act262.demo;

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.io.OutputStream;
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;
import javax.servlet.http.HttpSession;

import sun.java2d.loops.DrawLine;

/**
* 输出随机的验证码
*/
@WebServlet({ "/CheckCode", "/checkCode.jpg" })
public class CheckCodeServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

/* 宽度 */
private final int WIDTH = 100;
/* 高度 */
private final int HEIGHT = 20;
/* 生成验证码的个数 */
private final int COUNT = 4;
/* 干扰线条数 */
private final int LINE_ROW = 6;

/* 输出的基本码表，如果使用中文，则使用utf-8的码表，类似 \ue234 ，而且应该使用常用字，避免出现偏僻字 */
private final char[] BASECODE = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h',
'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u',
'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U',
'V', 'W', 'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9' };

// 写出数据
private void write(HttpServletRequest request, HttpServletResponse response)
throws IOException {
HttpSession session = request.getSession();

BufferedImage image = new BufferedImage(WIDTH, HEIGHT,
BufferedImage.TYPE_INT_RGB);
Graphics graphics = image.getGraphics();

setBackground(graphics);
drawBorder(graphics);
drawDot(graphics);
drawLine(graphics);
drawString(graphics, session);

// 写出数据流
ImageIO.write(image, "jpg", response.getOutputStream());

}

// 写字
private void drawString(Graphics graphics, HttpSession session) {
StringBuffer sb = new StringBuffer();
Random random = new Random();

graphics.setFont(new Font("宋体", Font.BOLD, 18));
graphics.setColor(Color.BLACK);

for (int i = 0; i < COUNT; i++) {
String ch = String
.valueOf(BASECODE[random.nextInt(BASECODE.length)]);
sb.append(ch);

// 设置位置
int x = i * 20 + random.nextInt(12) + 10;
int y = random.nextInt(HEIGHT / 3) + 12;

// 旋转字体
double theta = Math.PI / 180 * random.nextInt(20);
// rotate(graphics, theta);

graphics.drawString(ch, x, y);

// 恢复。。
// rotate(graphics, -theta);
}
session.setAttribute("checkCode", sb.toString());

System.out.println("session:" + session + "   验证码：" + sb.toString());
}

// 旋转
private void rotate(Graphics graphics, double theta) {
((Graphics2D) graphics).rotate(theta);
}

// 画随机线条
private void drawLine(Graphics graphics) {
Random random = new Random();
for (int i = 0; i < LINE_ROW; i++) {
int x1 = random.nextInt(WIDTH);
int y1 = random.nextInt(HEIGHT);
int x2 = random.nextInt(WIDTH);
int y2 = random.nextInt(HEIGHT);
setRandomColor(graphics);
graphics.drawLine(x1, y1, x2, y2);
}
}

// 画斑点
private void drawDot(Graphics graphics) {
Random random = new Random();
graphics.setColor(Color.red);
for (int i = 0; i < WIDTH; i++) {
int x = i;
int y = random.nextInt(HEIGHT);
int r = random.nextInt(2);
// graphics.fillOval(x, y, r, r);
graphics.drawOval(x, y, r, r);
}
}

// 画边框
private void drawBorder(Graphics graphics) {
graphics.setColor(Color.BLACK);
graphics.drawRect(1, 1, WIDTH - 2, HEIGHT - 2);
}

// 设置背景
private void setBackground(Graphics graphics) {
graphics.setColor(Color.WHITE);
graphics.fillRect(0, 0, WIDTH, HEIGHT);// 填充背景色
}

// 设置随机的画笔颜色
private void setRandomColor(Graphics g) {
Random random = new Random();
g.setColor(new Color(random.nextInt(255), random.nextInt(255), random
.nextInt(255)));
}

protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {

// 输出图片流的头信息
response.setContentType("image/jpeg");
response.setHeader("Expires", "-1");
response.setHeader("Cache-Control", "no-cache");

// 写出数据
write(request, response);

}

protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}

}

注册提交

package com.act262.demo;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
* Servlet implementation class RegisterServlet
*/
@WebServlet({ "/RegisterServlet", "/register.do" })
public class RegisterServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
HttpSession session = request.getSession();
String checkCode = (String) session.getAttribute("checkCode");

String paramsName = request.getParameter("name");
String paramsPwd = request.getParameter("pwd");
String paramsCheckCode = request.getParameter("checkCode").trim();

// do somethines

//
response.setContentType("text/html;charset=utf-8");
if (checkCode.equalsIgnoreCase(paramsCheckCode)) {
System.out.println("check code ok");
response.getWriter().write(
"尊敬的 <bold>" + paramsName + "</bold>用户，您的密码为：" + paramsPwd
+ "<br/>验证码 OK");
} else {
response.getWriter().write(
"尊敬的 <bold>" + paramsName + "</bold>用户，您的密码为：" + paramsPwd
+ "<br/>验证码 not OK");
}
}

protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}

}

jsp简单的界面

<%@ 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=ISO-8859-1">
<title>Insert title here</title>

</head>
<body>

<div>

<form action="register.do">
<label>用户名：</label><input type="text" name="name" /></br> <label>密
码：</label><input type="password" name="pwd" /></br> <label>验证码：</label><input
type="text" name="checkCode" /><img src="checkCode.jpg"
onclick=flushCheckCode(this) alt="点击刷新验证码" style="cursor: hand" /></br>
<input type="submit" value="注册" />
</form>

</div>

<script type="text/javascript">
function flushCheckCode(obj) {
obj.src = (obj.src + '?' + new Date())
}
</script>
</body>
</html>

這样子还是可以得，哈哈。。