用Java编写生成验证码程序

创建一个名为VerifyCode的类：

package com.sdbi.liuyouqi;

import javax.imageio.ImageIO;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

public class VerifyCode {
    private int width = 150;  //宽度
    private int height = 70;  //高度
    private Random r = new Random(); //获得一个随机数
    private String[] fontNames = {"宋体", "黑体", "微软雅黑", "华文楷体", "楷体_GB2312"};  //定义所用的字体
    private Color bgcolor = new Color(250, 250, 250);  //生成验证码的背景色
    private String Codes = "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ"; //定义验证码的随记字符
    private String text;

    //生成随机的颜色
    private Color randomColor() {
        int red = r.nextInt(150);
        int green = r.nextInt(150);
        int blue = r.nextInt(150);
        return new Color(red, green, blue);
    }

    //生成随机字体
    private Font randomFont() {
        int index = r.nextInt(fontNames.length);
        String fontName = fontNames[index]; //字体名称
        int style = r.nextInt(4); //字体样式
        int size = r.nextInt(5) + 50;  //字体大小(50~54之间)
        return new Font(fontName, style, size);
    }

    //画干扰线
    private void drawLine(BufferedImage image) {
        int num = 3; //干扰线数量
        Graphics2D g2 = (Graphics2D) image.getGraphics(); //得到图片画笔
        for (int i = 0; i < num; i++) {
            int x1 = r.nextInt(width);  //起点x坐标
            int y1 = r.nextInt(height);  //起点y坐标
            int x2 = r.nextInt(width);  //终点x坐标
            int y2 = r.nextInt(height);  //终点y坐标
            g2.setStroke(new BasicStroke(1.5F)); //设置线条特征，1.5F为线的宽度
            g2.setColor(Color.BLUE); //干扰线颜色
            g2.drawLine(x1, y1, x2, y2); //画线
        }
    }

    //得到codes的长度内的随机数，并使用charAt取得随机数位置上的codes中的字符
    private char randomChar() {
        int index = r.nextInt(Codes.length());
        return Codes.charAt(index);
    }

    //创建一张验证码的图片
    public BufferedImage createImage() {
        //得到一个图片缓冲区
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics2D g2 = (Graphics2D) image.getGraphics(); //得到图片画笔
        g2.setColor(bgcolor); //给画笔设置颜色
        g2.fillRect(0, 0, width, height); //使用画笔填充指定的矩形
        g2.setColor(Color.RED); //给画笔设置颜色
        g2.drawRect(0, 0, width - 1, height - 1); //使用画笔绘制指定的矩形
        StringBuilder sb = new StringBuilder();
        //向图中画四个字符
        for (int i = 0; i < 4; i++) {
            String s = randomChar() + "";
            sb.append(s);
            int x = i * width / 4; //计算字符x坐标位置
            g2.setFont(randomFont()); //设置画笔字体
            g2.setColor(randomColor()); //设置画笔颜色
            g2.drawString(s, x, height - 20); //在图片上写字符
        }
        text = sb.toString();
        drawLine(image); //绘制干扰线
        return image;
    }

    public void output(BufferedImage image, OutputStream output) throws IOException {
        System.out.println("output");
        ImageIO.write(image, "jpeg", output);
    }

    public String getText() {
        System.out.println("getText");
        return text;
    }
}

创建一个名为VerifyCodeTest的测试类：

package com.sdbi.liuyouqi;

import java.awt.image.BufferedImage;
import java.io.FileOutputStream;
import java.io.IOException;

public class VerifyCodeTest {
    public static void main(String[] args) throws IOException {
        VerifyCode code = new VerifyCode();
        BufferedImage image = code.createImage();
        code.output(image, new FileOutputStream("D:\\output\\image.jpg"));
        System.out.println("验证码的真实文本是："+code.getText()); //输出验证码文本
    }
}

运行一次随机生成代码，如下所示：

控制台显示结果：

 随记验证码图片：