生成验证码

代码如下：

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

import javax.imageio.ImageIO;

public class VerifyCode {
    private int w = 70;
    private int h = 35;
    private Random r = new Random();
    // {"宋体", "华文楷体", "黑体", "华文新魏", "华文隶书", "微软雅黑", "楷体_GB2312"}
    private String[] fontNames  = {"宋体", "华文楷体", "黑体", "微软雅黑", "楷体_GB2312"};
    // 可选字符
    private String codes  = "23456789abcdefghjkmnopqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ";
    // 背景色
    private Color bgColor  = new Color(255, 255, 255);
    // 验证码上的文本
    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);
    }

    // 生成随机的字体
    private Font randomFont () {
        int index = r.nextInt(fontNames.length);
        String fontName = fontNames[index];//生成随机的字体名称
        int style = r.nextInt(4);//生成随机的样式, 0(无样式), 1(粗体), 2(斜体), 3(粗体+斜体)
        int size = r.nextInt(5) + 24; //生成随机字号, 24 ~ 28
        return new Font(fontName, style, size);
    }

    // 画干扰线
    private void drawLine (BufferedImage image) {
        int num  = 3;//一共画3条
        Graphics2D g2 = (Graphics2D)image.getGraphics();
        for(int i = 0; i < num; i++) {//生成两个点的坐标，即4个值
            int x1 = r.nextInt(w);
            int y1 = r.nextInt(h);
            int x2 = r.nextInt(w);
            int y2 = r.nextInt(h); 
            g2.setStroke(new BasicStroke(1.5F)); 
            g2.setColor(Color.BLUE); //干扰线是蓝色
            g2.drawLine(x1, y1, x2, y2);//画线
        }
    }

    // 随机生成一个字符
    private char randomChar () {
        int index = r.nextInt(codes.length());
        return codes.charAt(index);
    }

    // 创建BufferedImage
    private BufferedImage createImage () {
        BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB); 
        Graphics2D g2 = (Graphics2D)image.getGraphics(); 
        g2.setColor(this.bgColor);
        g2.fillRect(0, 0, w, h);
        return image;
    }

    // 调用这个方法得到验证码
    public BufferedImage getImage () {
        BufferedImage image = createImage();//创建图片缓冲区 
        Graphics2D g2 = (Graphics2D)image.getGraphics();//得到绘制环境
        StringBuilder sb = new StringBuilder();//用来装载生成的验证码文本
        // 向图片中画4个字符
        for(int i = 0; i < 4; i++)  {//循环四次，每次生成一个字符
            String s = randomChar() + "";//随机生成一个字母 
            sb.append(s); //把字母添加到sb中
            float x = i * 1.0F * w / 4; //设置当前字符的x轴坐标
            g2.setFont(randomFont()); //设置随机字体
            g2.setColor(randomColor()); //设置随机颜色
            g2.drawString(s, x, h-5); //画图
        }
        this.text = sb.toString(); //把生成的字符串赋给了this.text
        drawLine(image); //添加干扰线
        return image;       
    }

    // 返回验证码图片上的文本
    public String getText () {
        return text;
    }

    // 保存图片到指定的输出流
    public static void output (BufferedImage image, OutputStream out) 
                throws IOException {
        ImageIO.write(image, "JPEG", out);
    }
}

使用如下：

package cn.itcast.image;

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import javax.imageio.ImageIO;

import org.junit.Test;

/** * 动态生成图片 * @author cxf * */
public class Demo {
    @Test
    public void fun1() throws FileNotFoundException, IOException {
        /* * 1. 创建图片缓冲区 * 2. 设置其宽高 * 3. 得到这个图片的绘制环境（得到画笔） * 4. 保存起来 */
        BufferedImage bi = new BufferedImage(70, 35, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = (Graphics2D)bi.getGraphics();//得到绘制环境
        g.setColor(Color.WHITE);//把环境设置为白色
        g.fillRect(0, 0, 70, 35);//填充矩形！填充矩形，从0,0点开始，宽70，高35，即整个图片，即为图片设置背景色
        g.setColor(Color.RED);//把环境设置为红色
        g.drawString("Hello", 2, 35-2);//向图片上写入字符串，其中2,2表示x,y轴的坐标

        ImageIO.write(bi, "JPEG", new FileOutputStream("F:/xxx.jpg"));
    }

    @Test
    public void fun2() throws FileNotFoundException, IOException {
        VerifyCode vc = new VerifyCode();
        BufferedImage bi = vc.getImage();
        VerifyCode.output(bi, new FileOutputStream("F:/xxx.jpg"));

        System.out.println(vc.getText());
    }
}