Java验证码生成

package com.jbit.diamonds.util;


import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.imageio.stream.ImageOutputStream;


public class RandomNumUtil {
private ByteArrayInputStream image;//图像
private String str;//验证码


private RandomNumUtil() {
init();// 初始化属性
}


/*
* 取得RandomNumUtil实例
*/
public static RandomNumUtil Instance() {
return new RandomNumUtil();
}


/*
* 取得验证码图片
*/
public ByteArrayInputStream getImage() {
return this.image;
}


/*
* 取得图片的验证码
*/
public String getString() {
return this.str;
}


private void init() {
//在内存中创建图象
int width = 77, height = 30;
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
//获取图形上下文
Graphics g = image.getGraphics();
//生成随机类
Random random = new Random();
//设定背景色
g.setColor(getRandColor(200, 250));
g.fillRect(0, 0, width, height);
//设定字体
g.setFont(new Font("Times New Roman", Font.PLAIN, 22));
//随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
g.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++) {
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
g.drawLine(x, y, x + xl, y + yl);
}
// 取随机产生的认证码(5位数字)
String sRand = "";
for (int i = 0; i < 5; i++) {
String rand = String.valueOf(random.nextInt(10));
sRand += rand;
// 将认证码显示到图象中
g.setColor(new Color(20 + random.nextInt(110), 20 + random
.nextInt(110), 20 + random.nextInt(110)));
//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
g.drawString(rand, 13 * i + 6, 22);
}
//赋值验证码
this.str = sRand;


// 图象生效
g.dispose();
ByteArrayInputStream input = null;
ByteArrayOutputStream output = new ByteArrayOutputStream();
try {
ImageOutputStream imageOut = ImageIO
.createImageOutputStream(output);
ImageIO.write(image, "JPEG", imageOut);
imageOut.close();
input = new ByteArrayInputStream(output.toByteArray());
} catch (Exception e) {
System.out.println("验证码图片产生出现错误" + e.toString());
}


this.image = input;/* 赋值图像*/
}


/*
*给定范围获得随机颜色
*/
private Color getRandColor(int fc, int bc) {
Random random = new Random();
if (fc > 255)
fc = 255;
if (bc > 255)
bc = 255;
int r = fc + random.nextInt(bc - fc);
int g = fc + random.nextInt(bc - fc);
int b = fc + random.nextInt(bc - fc);
return new Color(r, g, b);
}
}