java 生成验证码
1、新建一个servelet 名字叫ImageRandServlet
2、在doget方法中填写如下代码
3、ImageRandServlet 类的代码如下：
import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import java.awt.Font;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ImageRandServlet extends HttpServlet {
private static final String CONTENT_TYPE = "image/jpeg";
//Initialize global variables
public void init() throws ServletException {
}
//Process the HTTP Get request
public void doGet(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException {
try {
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
int width = 60, height = 20;
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
OutputStream os = response.getOutputStream();
Graphics g = image.getGraphics();
Random random = new Random();
g.setColor(getRandColor(200, 250));
g.fillRect(0, 0, width, height);
g.setFont(new Font("Arial", Font.PLAIN, 18));
g.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++) {
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
g.drawLine(x, y, x + xl, y + yl);
}
String sRand = "";
for (int j = 0; j < 4; j++) {
String rand = String.valueOf(random.nextInt(10));
sRand += rand;
g.setColor(new Color(20 + random.nextInt(110), 20 + random
.nextInt(110), 20 + random.nextInt(110)));
g.drawString(rand, 13 * j + 6, 16);
}
request.getSession().setAttribute("rand", sRand);
g.dispose();
ImageIO.write(image, "JPEG", os);
os.flush();
os.close();
os = null;
response.flushBuffer();
// out.clear();
// out = pageContext.pushBody();
} catch (IllegalStateException e) {
e.printStackTrace();
}
}
//Process the HTTP Post request
public void doPost(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException {
doGet(request, response);
}
//Clean up resources
public void destroy() {
}
public Color getRandColor(int fc, int bc) {
Random random = new Random();
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);
}
}
1、新建test.jsp页面，此页面是来现实验证码的界面
2、在<body></body>之间添加如下代码：<img src="servlet/imageRandServlet">
3、jsp代码如下：
<%@ 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 'test.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">
-->
</head>
<body>
<img src="<%=basePath%>servlet/imageRandServlet">
</body>
</html>
1、在WEB-INF目录下找到web.xml 在<web-app></web-app>节点之间添加
<servlet>
<servlet-name>imageRandServlet</servlet-name>
<servlet-class>com.xianmeixian.util.ImageRandServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>imageRandServlet</servlet-name>
<url-pattern>/servlet/imageRandServlet</url-pattern>
</servlet-mapping>
2、运行程序，结果如下
