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；