页面
<%@ page language="java" contentType="text/html; charset=UTF-8"
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" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<base href="<%=basePath%>">
<title>Insert title here</title>
<script type="text/javascript">
var changeimg = function(img){
var timenow = new Date().getTime() ;
img.src=\‘#\‘" /script>
</head>
<body>
<img src="imgServlet" id="safeCodeImg" onclick="changeimg(this)" style="width: 60px;height: 20px;"/>
<img src="img2Servlet" onclick="changeimg2(this)" />
</body>
</html>后台：servlet
package com.liu.servlet;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
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;
/**
* Servlet implementation class ImgServlet
*/
@WebServlet("/img2Servlet")
public class Img2Servlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* 获取随机颜色
* @param fc
* @param bc
* @return
*/
private Color getColor(int fc, int bc) {
Random random = new Random();
if (fc > 255)
fc = 255;
if (fc < 0)
fc = 0;
if (bc > 255)
bc = 255;
if (bc < 0)
bc = 0;
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);
}
/**
* @see HttpServlet#HttpServlet()
*/
public Img2Servlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// 设置输出 必须设置为这个
response.setContentType("image/jpeg");
// 产生随机数
Random r = new Random();
// 把随机数绘制成图像
BufferedImage imgbuf = new BufferedImage(60, 20,
BufferedImage.TYPE_INT_RGB);// 产生缓冲图像,40宽20高
Graphics2D g = imgbuf.createGraphics();// 取得缓冲的绘制环境
// 开始绘制
g.setColor(getColor(200, 250));// 设定背景色
g.fillRect(0, 0, width, height);
// 随机产生15条干扰线
g.setColor(getColor(160, 200));
for (int i = 0; i < 15; i++) {
int x = r.nextInt(width);
int y = r.nextInt(height);
int xl = r.nextInt(12);
int yl = r.nextInt(12);
g.drawLine(x, y, x + xl, y + yl);
}
// 随机产生100个干扰点，使图像中的验证码不易被其他分析程序探测到
g.setColor(getColor(120, 240));
for (int i = 0; i < 100; i++) {
int x = r.nextInt(width);
int y = r.nextInt(height);
g.drawOval(x, y, 0, 0);
}
g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
String scode = "";
for (int i = 0; i < 4; i++) {
String rand = String.valueOf(r.nextInt(10));
scode += rand;
g.setColor(new Color(20 + r.nextInt(110), 20 + r.nextInt(110),
20 + r.nextInt(110)));
// 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
g.drawString(rand, 13 * i + 6, 16);
}
//保存到session中
request.getSession().setAttribute("code", scode);
// 输出图片 通过流的方式
ServletOutputStream out = response.getOutputStream();
// JPEGCodec.createJPEGEncoder(out);转码
// 产生JPEG的图像加码器
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
encoder.encode(imgbuf);
out.flush();
}
}package com.liu.servlet;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Date;
import java.util.Random;
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 com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGEncodeParam;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
/**
* Servlet implementation class ImgServlet
*/
@WebServlet("/imgServlet")
public class ImgServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public ImgServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// 必须设置image/jpeg
response.setContentType("image/jpeg");
int length = 4; // 设置默认生成4个数字
Date d = new Date();
long lseed = d.getTime();
java.util.Random r = new Random(lseed); // 设置随机种子
StringBuffer str = new StringBuffer();
for (int i = 0; i < length; i++) {
str.append(r.nextInt(9)); // 生成随机数字
}
// 可以在此加入保存验证码的代码
// 创建内存图像
BufferedImage bi = new BufferedImage(40, 16, BufferedImage.TYPE_INT_RGB);
Graphics2D g = bi.createGraphics();
g.clearRect(0, 0, 16, 40);
g.setColor(Color.green.CYAN);
System.out.println("--------------"+str);
g.drawString(str.toString(), 4, 12);
try {
// 输出图片
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(response
.getOutputStream());
JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(bi);
param.setQuality(1.0f, false);
encoder.setJPEGEncodeParam(param);
encoder.encode(bi);
} catch (Exception ex) {
}
}
}
效果
本文出自 “老牛Java” 博客，请务必保留此出处http://liuyj.blog.51cto.com/2340749/1572350
原文地址：http://liuyj.blog.51cto.com/2340749/1572350
