<span style="font-size:18px;">package com.java.process.jsp;
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.imageio.ImageIO;
import javax.servlet.Servlet;
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;
</span>
<span style="font-size:18px;">
</span>
<span style="font-size:18px;"></span><pre name="code" class="java">
<span style="font-size:18px;">//servlet3.0之前必须是在web.xml中配置</span>
<span style="font-size:18px;"></span><pre name="code" class="html"> <servlet>
<servlet-name>validateColorServlet</servlet-name>
<servlet-class>com.atguigu.javaweb.ValidateColorServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>validateColorServlet</servlet-name>
<url-pattern>/validateColorServlet</url-pattern>
</servlet-mapping>
<span style="font-size: 18px;">//servlet3.0以后就是能够直接用@WebServlet,</span>
<span style="font-size:18px;">@WebServlet("/validateColorServlet")
public class ValidateColorServlet extends HttpServlet {
public static final String CHECK_CODE_KEY = "CHECK_CODE_KEY";
private static final long serialVersionUID = 1L;
//设置验证图片的宽度, 高度, 验证码的个数
private int width = 152;
private int height = 40;
private int codeCount = 6;
//验证码字体的高度
private int fontHeight = 4;
//验证码中的单个字符基线. 即:验证码中的单个字符位于验证码图形左上角的 (codeX, codeY) 位置处
private int codeX = 0;
private int codeY = 0;
//验证码由哪些字符组成
char [] codeSequence = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz23456789".toCharArray();
//初始化验证码图形属性
public void init(){
fontHeight = height - 2;
codeX = width / (codeCount + 2);
codeY = height - 4;
}
public void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//定义一个类型为 BufferedImage.TYPE_INT_BGR 类型的图像缓存
BufferedImage buffImg = null;
buffImg = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);
//在 buffImg 中创建一个 Graphics2D 图像
Graphics2D graphics = null;
graphics = buffImg.createGraphics();
//设置一个颜色, 使 Graphics2D 对象的兴许图形使用这个颜色
graphics.setColor(Color.WHITE);
//填充一个指定的矩形: x - 要填充矩形的 x 坐标; y - 要填充矩形的 y 坐标; width - 要填充矩形的宽度; height - 要填充矩形的高度
graphics.fillRect(0, 0, width, height);
//创建一个 Font 对象: name - 字体名称; style - Font 的样式常量; size - Font 的点大小
Font font = null;
font = new Font("", Font.BOLD, fontHeight);
//使 Graphics2D 对象的兴许图形使用此字体
graphics.setFont(font);
graphics.setColor(Color.BLACK);
//绘制指定矩形的边框, 绘制出的矩形将比构件宽一个也高一个像素
graphics.drawRect(0, 0, width - 1, height - 1);
//随机产生 15 条干扰线, 使图像中的认证码不易被其他程序探測到
Random random = null;
random = new Random();
graphics.setColor(Color.GREEN);
for(int i = 0; i < 55; i++){
int x = random.nextInt(width);
int y = random.nextInt(height);
int x1 = random.nextInt(20);
int y1 = random.nextInt(20);
graphics.drawLine(x, y, x + x1, y + y1);
}
//创建 randomCode 对象, 用于保存随机产生的验证码, 以便用户登录后进行验证
StringBuffer randomCode;
randomCode = new StringBuffer();
for(int i = 0; i < codeCount; i++){
//得到随机产生的验证码数字
String strRand = null;
strRand = String.valueOf(codeSequence[random.nextInt(36)]);
//把正在产生的随机字符放入到 StringBuffer 中
randomCode.append(strRand);
//用随机产生的颜色将验证码绘制到图像中
graphics.setColor(Color.BLUE);
graphics.drawString(strRand, (i + 1)* codeX, codeY);
}
//再把存放有全部随机字符的 StringBuffer 相应的字符串放入到 HttpSession 中
request.getSession().setAttribute(CHECK_CODE_KEY, randomCode.toString());
//禁止图像缓存
response.setHeader("Pragma", "no-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
//将图像输出到输出流中
ServletOutputStream sos = null;
sos = response.getOutputStream();
ImageIO.write(buffImg, "jpeg", sos);
sos.close();
}
}</span>