Java实现简单验证码生成-优快云博客

本文介绍了如何使用Java来制作验证码，包括随机生成字符、设置验证码背景及样式、添加混淆元素如线条和噪点，最终展示真实效果图并提供完整源代码。

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验证码往往由a-z，0-9等字符组成，所以我们可以设计一个方法，根据参数x随机返回x个字符，具体代码如下:

public String randString(int count){
        StringBuilder builder = new StringBuilder();
        String str = "abcdefghijklmnpqrstuvwxy0123456789";
        Random rnd = new Random();
        for(int i=0;i<count;i++){
            int pos = rnd.nextInt(str.length());
            String s =str.substring(pos,pos+1);
            builder.append(s);
        }

       return builder.toString();
    }

制作验证码还需要画笔

BufferedImage img = new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_INT_RGB);
        Graphics g = img.getGraphics();

建一个随机变量，下面步骤要用到

Random r =new Random();

设置验证码背景画布

g.setColor(Color.white);
g.fillRect(0,0,WIDTH,HEIGHT);

设置验证码字符样式以及绘制验证码

g.setColor(Color.RED);
        g.setFont(new Font("宋体",Font.PLAIN,36));
        String code = randString(4);
        g.drawString(code,20,50);

添加混淆视野的线条

for(int i=0;i<10;i++){
            g.setColor(Color.BLUE);
            g.drawLine(r.nextInt(WIDTH), r.nextInt(HEIGHT), r.nextInt(WIDTH), r.nextInt(HEIGHT));
        }

添加混淆视野的噪点

for(int j=0;j<10;j++){
            g.drawOval(r.nextInt(WIDTH),r.nextInt(HEIGHT),5,5);
        }

真实效果图:
在这里插入图片描述

完整源代码:

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

@WebServlet("/captche")
public class CaptcheController  extends HttpServlet {
    private final int WIDTH=100;
    private final int HEIGHT=80;
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        BufferedImage img = new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_INT_RGB);
        Graphics g = img.getGraphics();
        Random r =new Random();
        g.setColor(Color.white);
        g.fillRect(0,0,WIDTH,HEIGHT);
        g.setColor(Color.RED);
        g.setFont(new Font("宋体",Font.PLAIN,36));
        String code = randString(4);
        g.drawString(code,20,50);
        for(int i=0;i<10;i++){
            g.setColor(Color.BLUE);
            g.drawLine(r.nextInt(WIDTH), r.nextInt(HEIGHT), r.nextInt(WIDTH), r.nextInt(HEIGHT));
        }
        for(int j=0;j<10;j++){
            g.drawOval(r.nextInt(WIDTH),r.nextInt(HEIGHT),5,5);
        }

        g.dispose();
        ServletOutputStream out =resp.getOutputStream();
        ImageIO.write(img,"jpg",out);
        try{
            out.flush();
        }finally{
            out.close();
        }

    }
    public String randString(int count){
        StringBuilder builder = new StringBuilder();
        String str = "abcdefghijklmnpqrstuvwxy0123456789";
        Random rnd = new Random();
        for(int i=0;i<count;i++){
            int pos = rnd.nextInt(str.length());
            String s =str.substring(pos,pos+1);
            builder.append(s);
        }

       return builder.toString();
    }

}

java制作简易的验证码