用javase写一个类实现自动生成验证码的功能，验证码随机自动生成；

用java写一个类实现自动生成验证码的功能，验证码随机自动生成；

好了，直接上代码吧；//代码中有注释；有javase基础都可以看懂的；

package cn.mike.javase.vefification_code;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

import javax.imageio.ImageIO;

import org.junit.Test;

/**
 * @author : Administrator
 * @function : 这是用来测试随机生成验证码图片的类；
 */
public class VerificationCode {

	/**
	 * 单元测试，试一下能不能自动生成验证码图片
	 */
	@Test
	public void test_fun() {
		VerificationCode vc = new VerificationCode();
		BufferedImage image = vc.getImage();
		try {
			// 生成验证码图片，并保存到指定的路径
			VerificationCode.output(image, new FileOutputStream(new File(
					".\\image\\vcode_2.jpg")));
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}

		// 将随机生成的文本内容输出到控制台，用于校验
		System.out.println(vc.getText());
	}

	private int w = 70;// 宽
	private int h = 35;// 高
	private String text;// 文本内容(验证码字符串)
	private Random r = new Random();
	private String[] fontNames = { "宋体", "华文楷体", "黑体", "微软雅黑", "楷体_GB2312" };
	// 随机字符集合中不包括0和o，O，1和l，因为这些不易区分
	private String codes = "23456789abcdefghijkmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYXZ";
	// 验证码图片的背景色：白色
	private Color bgColor = new Color(255, 255, 255);

	/**
	 * 返回一个验证码图片buffer对象：BufferedImage
	 */
	public BufferedImage getImage() {
		BufferedImage image = createImage();
		// 获取绘图环境（画笔工具）
		Graphics2D g2 = (Graphics2D) image.getGraphics();
		// sb ： 用来保存验证码字符串文本内容
		StringBuilder sb = new StringBuilder();

		for (int i = 0; i < 4; ++i) {// 随机生成4个字符
			String s = randomChar() + "";
			sb.append(s);
			float x = i * 1.0F * w / 4;
			g2.setFont(randomFont());
			g2.setColor(randomColor());
			g2.drawString(s, x, h - 5);
		}

		this.text = sb.toString();// 记录验证码文本内容
		drawLine(image);// 画干扰线
		return image;

	}

	/**
	 * @return 获取验证码文本内容
	 */
	public String getText() {
		return text;
	}

	/**
	 * @param image
	 * @param out
	 *            将文本写到指定的输出流。比如本测试中FileOutputStream指定的保存路径
	 */
	public static void output(BufferedImage image, OutputStream out) {
		try {
			ImageIO.write(image, "jpeg", out);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	private void drawLine(BufferedImage image) {
		Graphics2D g2 = (Graphics2D) image.getGraphics();
		for (int i = 0; i < 3; ++i) {// 画3条干扰线
			int x1 = r.nextInt(w);
			int y1 = r.nextInt(h);
			int x2 = r.nextInt(w);
			int y2 = r.nextInt(h);
			g2.setColor(Color.BLUE);
			g2.drawLine(x1, y1, x2, y2);
		}
	}

	private Color randomColor() {
		int red = r.nextInt(150);
		int green = r.nextInt(150);
		int blue = r.nextInt(150);
		return new Color(red, green, blue);
	}

	private Font randomFont() {
		int index = r.nextInt(fontNames.length);
		String fontName = fontNames[index];
		int style = r.nextInt(4);
		int size = r.nextInt(5) + 24;
		return new Font(fontName, style, size);
	}

	private char randomChar() {
		int index = r.nextInt(codes.length());
		return codes.charAt(index);
	}

	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;
	}

}

随机生成图片的效果图；