java生成图片验证码的源码

package com.sjl.common;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

public class ImageServlet extends HttpServlet {
String[] random = { "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" };

@Override
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
int width = 130;
int height = 50;
// 设置响应格式
response.setContentType("image/jpeg");
// 获得输出流
OutputStream os = response.getOutputStream();
// 创建图片内存对象 给定长，宽 和格式
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 创建画笔
Graphics g = image.createGraphics();
Random ran = new Random();
// 先给画笔设置颜色
g.setColor(new Color(ran.nextInt(256), ran.nextInt(256), ran
.nextInt(256)));
// 画矩形
g.fillRect(0, 0, width, height);
// 设置字体 Font(String name,int style,int size)指定名称、样式和磅值大小
Font font = new Font("宋体", Font.BOLD, 36);
g.setFont(font);
//最终生成验证码信息
StringBuffer sb = new StringBuffer();
//定义验证码位置
int[] wid = {15,45,75,105};
int[] hei = {35,40,30,28};
// 绘制四位验证码
for(int i=0;i<wid.length;i++){
String str = random[ran.nextInt(62)];
sb.append(str);
g.setColor(new Color(ran.nextInt(256), ran.nextInt(256), ran
.nextInt(256)));
g.drawString(str, wid[i], hei[i]);
}

//将验证码发在session中
request.getSession().setAttribute("chkCode", sb.toString());

// 绘制干扰线
for (int i = 0; i < 6; i++) {
g.setColor(new Color(ran.nextInt(256), ran.nextInt(256), ran
.nextInt(256)));
g.drawLine(ran.nextInt(width), ran.nextInt(height), ran
.nextInt(width), ran.nextInt(height));
}

// 将位图转为jpeg 格式传输
// 使用JPEGImageEncoder 可以一边转换一边输出 把输出流传入
JPEGImageEncoder encode = JPEGCodec.createJPEGEncoder(os);

// 把BufferedImage对象中的图像信息编码后
// 向创建该对象(encoder)时指定的输出流输出
encode.encode(image);

}

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

}

在SpringMVC中的写法：

package com.sjl.controller;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

@Controller
@RequestMapping("/image")
public class ImageController {

String[] random = { "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" };

@RequestMapping("/chkcode")
public void chkcodeImage(HttpServletRequest request, HttpServletResponse response) throws IOException {
int width = 130;
int height = 50;
// 设置响应格式
response.setContentType("image/jpeg");
// 获得输出流
OutputStream os = response.getOutputStream();
// 创建图片内存对象 给定长，宽 和格式
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 创建画笔
Graphics g = image.createGraphics();
Random ran = new Random();
// 先给画笔设置颜色
g.setColor(new Color(ran.nextInt(256), ran.nextInt(256), ran
.nextInt(256)));
// 画矩形
g.fillRect(0, 0, width, height);
// 设置字体 Font(String name,int style,int size)指定名称、样式和磅值大小
Font font = new Font("宋体", Font.BOLD, 36);
g.setFont(font);
//最终生成验证码信息
StringBuffer sb = new StringBuffer();
//定义验证码位置
int[] wid = {15,45,75,105};
int[] hei = {35,40,30,28};
// 绘制四位验证码
for(int i=0;i<wid.length;i++){
String str = random[ran.nextInt(62)];
sb.append(str);
g.setColor(new Color(ran.nextInt(256), ran.nextInt(256), ran
.nextInt(256)));
g.drawString(str, wid[i], hei[i]);
}

//将验证码发在session中
request.getSession().setAttribute("chkCode", sb.toString());

// 绘制干扰线
for (int i = 0; i < 6; i++) {
g.setColor(new Color(ran.nextInt(256), ran.nextInt(256), ran
.nextInt(256)));
g.drawLine(ran.nextInt(width), ran.nextInt(height), ran
.nextInt(width), ran.nextInt(height));
}

// 将位图转为jpeg 格式传输
// 使用JPEGImageEncoder 可以一边转换一边输出 把输出流传入
JPEGImageEncoder encode = JPEGCodec.createJPEGEncoder(os);

// 把BufferedImage对象中的图像信息编码后
// 向创建该对象(encoder)时指定的输出流输出
encode.encode(image);
}
@RequestMapping("/downloadImage.jpeg")
public void downloadImage(HttpServletRequest request, HttpServletResponse response) throws IOException {
int width = 130;
int height = 50;
// 设置响应格式
response.setContentType("application/octet-stream");
// 获得输出流
OutputStream os = response.getOutputStream();
// 创建图片内存对象 给定长，宽 和格式
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 创建画笔
Graphics g = image.createGraphics();
Random ran = new Random();
// 先给画笔设置颜色
g.setColor(new Color(ran.nextInt(256), ran.nextInt(256), ran
.nextInt(256)));
// 画矩形
g.fillRect(0, 0, width, height);
// 设置字体 Font(String name,int style,int size)指定名称、样式和磅值大小
Font font = new Font("宋体", Font.BOLD, 36);
g.setFont(font);
//最终生成验证码信息
StringBuffer sb = new StringBuffer();
//定义验证码位置
int[] wid = {15,45,75,105};
int[] hei = {35,40,30,28};
// 绘制四位验证码
for(int i=0;i<wid.length;i++){
String str = random[ran.nextInt(62)];
sb.append(str);
g.setColor(new Color(ran.nextInt(256), ran.nextInt(256), ran
.nextInt(256)));
g.drawString(str, wid[i], hei[i]);
}

//将验证码发在session中
request.getSession().setAttribute("chkCode", sb.toString());

// 绘制干扰线
for (int i = 0; i < 6; i++) {
g.setColor(new Color(ran.nextInt(256), ran.nextInt(256), ran
.nextInt(256)));
g.drawLine(ran.nextInt(width), ran.nextInt(height), ran
.nextInt(width), ran.nextInt(height));
}

// 将位图转为jpeg 格式传输
// 使用JPEGImageEncoder 可以一边转换一边输出 把输出流传入
JPEGImageEncoder encode = JPEGCodec.createJPEGEncoder(os);

// 把BufferedImage对象中的图像信息编码后
// 向创建该对象(encoder)时指定的输出流输出
encode.encode(image);
}

}

假定该servlet 的 对应url 为 image/chkcode， 那么前台的HTML代码如下：

HTML代码：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">

<title>My JSP 'chkcodeImage.jsp' starting page</title>

<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
<script type="text/javascript" src="js/jquery.js"></script>
</head>

<body>
<img id="chkcode" src="image/chkcode" onclick="reload()"/>
<a href="image/chkcode">显示原图</a>
<a href="image/downloadImage.jpeg">下载图像</a>

</body>

<script type="text/javascript">
function reload() {

$("#chkcode").attr("src", "image/chkcode/?q="+Math.random());
//$("#chkcode").attr("src", "image/chkcode");
}

</script>
</html>

注： reload 方法的使用， 通过更改src的值， 就可以实现点击图片的时候让图片重新加载实现图片刷新效果。但要注意的是， 在图片地址src不变的情况下让浏览器重新加载图片的话， 浏览器直接就去读取缓存了， 所以需要在地址后面通过加上"?querystring"的方式使得浏览器不读缓存，重新发起请求加载图片；这里的querystring可以随便写。