动态生成验证码的简单实现-蒲公英云

动态生成验证码的简单实现

功能描述：生成一张验证码并输出到页面上；点击验证码或文字，更换验证码

简单来说，就分三步：生成一张图片 -> 美化图片 -> 将图片输出到页面；话不多说，看代码：

验证码Servlet

import javax.imageio.ImageIO;
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 java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

@WebServlet(“/checkCodeServlet”)
public class CheckCodeServlet extends HttpServlet {

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    int width = 100;
    int height = 50;
    //1.创建一个对象，在内存中代表验证码图片对象
    BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
    //2.美化图片
    //2.1填充背景色
    Graphics g = image.getGraphics();//画笔对象
    g.setColor(Color.PINK);//设置画笔颜色
    g.fillRect(0,0,width,height);//填充背景色
    //2.2画边框(边框本来有1px的宽度)
    g.setColor(Color.BLUE);
    g.drawRect(0,0,width-1,height-1);
    //2.3写验证码
    //2.3.1生成随机的验证码
    String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";
        //生成随机角标
    Random ran = new Random();
    for(int i = 1; i <= 4; i++){
        int index = ran.nextInt(str.length());
        char ch = str.charAt(index);
        g.drawString(ch+"",width/5*i,height/2);//写验证码
    }
    //2.3.2画干扰线
    g.setColor(Color.CYAN);
    for(int i = 0; i < 10; i++){
//随机生成坐标点
        int x1 = ran.nextInt(width);
        int x2 = ran.nextInt(width);
        int y1 = ran.nextInt(height);
        int y2 = ran.nextInt(height);
        g.drawLine(x1,y1,x2,y2);
    }
    //3.将图片输出到页面展示
    ImageIO.write(image,"jpg",response.getOutputStream());//将内存中的图片写到任意流里面去
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    this.doPost(request,response);
}