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jsp页面验证码完整实例
本文实例为大家分享了sp页面验证码的具体代码，供大家参考，具体内容如下
项目结构如下，MyEclipse中新建一个Web Project，取名servlet
1、src下new一个servlet类
package com.servlet;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
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 IdentityServlet extends HttpServlet {
public static final char[] chars={'2','3','4','5','6','7','8','9','A'};//自定义验证码池
public static Random random=new Random();　　//随机数
public static String getRandomString(){　　//获取6位随机数，放在图片里
StringBuffer buffer=new StringBuffer();
for(int i=0;i<6;i++){
buffer.append(chars[random.nextInt(chars.length)]);
}
return buffer.toString();
}
public static Color getRandomColor(){　　//获取随机的颜色
return new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255));
}
public static Color getReverseColor(Color c){　　//返回某颜色的反色
return new Color(255 - c.getRed(), 255 - c.getGreen(), 255 - c.getBlue());
}
/**
* Constructor of the object.
*/
public IdentityServlet() {
super();
}
/**
* Destruction of the servlet.

*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet.

*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("image/jpeg");　　//设置输出类型
String randomString = getRandomString();　　//随机字符串
request.getSession(true).setAttribute("randomString", randomString);//放到session里
int width=100;　　//图片宽度
int height=30;　　//图片高度
Color color=getRandomColor();　　//随机颜色，用于背景色
Color reverse=getReverseColor(color);//反色，用于前景色
//创建一个彩色图片
BufferedImage bi=new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics2D g=bi.createGraphics();　　//绘图对象
g.setFont(new Font(Font.SANS_SERIF,Font.BOLD,16));//设置字体
g.setColor(color);//设置颜色
g.fillRect(0, 0, width, height);//绘制背景
g.setColor(reverse);
g.drawString(randomString, 18, 20);//绘制随机字符
for(int i=0,n=random.nextInt(100);ig.drawRect(random.nextInt(width), random.nextInt(height), 1, 1);
}
ServletOutputStream out= response.getOutputStream();//转成JPEG格式
JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(out);//编码器
encoder.encode(bi);　　//对图片进行编码
out.flush();　　//输出到客户端
}
/**
* The doPost method of the servlet.

*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
/**
* Initialization of the servlet.

*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}
2、web.xml，会自动生成servlet和servlet-mapping的配置

xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">


IdentityServlet
com.servlet.IdentityServlet


IdentityServlet
/servlet/IdentityServlet


index.jsp


3、WebRoot下新建一个html，展示验证码












启动Tomcat，输入网址：http://localhost:8080/servlet/identity.html，效果如下：
点击‘换个图片'，会生成新的验证码。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持中文源码网。