EasyCaptcha/src/main/java/com/wf/captcha/GifCaptcha.java

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Java
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package com.wf.captcha;
import java.awt.AlphaComposite;
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;
/**
* <p>Gif验证码类</p>
*
* @author: wuhongjun
* @version:1.0
*/
public class GifCaptcha extends Captcha
{
public GifCaptcha()
{
}
public GifCaptcha(int width,int height){
this.width = width;
this.height = height;
alphas();
}
public GifCaptcha(int width,int height,int len){
this(width,height);
this.len = len;
}
public GifCaptcha(int width,int height,int len,Font font)
{
this(width,height,len);
this.font = font;
}
@Override
public void out(OutputStream os)
{
try
{
GifEncoder gifEncoder = new GifEncoder(); // gif编码类这个利用了洋人写的编码类所有类都在附件中
//生成字符
gifEncoder.start(os);
gifEncoder.setQuality(180);
gifEncoder.setDelay(100);
gifEncoder.setRepeat(0);
BufferedImage frame;
char[] rands = textChar();
Color fontcolor[]=new Color[len];
for(int i=0;i<len;i++)
{
fontcolor[i]=new Color(20 + num(110), 20 + num(110), 20 + num(110));
}
for(int i=0;i<len;i++)
{
frame=graphicsImage(fontcolor, rands, i);
gifEncoder.addFrame(frame);
frame.flush();
}
gifEncoder.finish();
}finally
{
try {
os.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* 画随机码图
* @param fontcolor 随机字体颜色
* @param strs 字符数组
* @param flag 透明度使用
* @return BufferedImage
*/
private BufferedImage graphicsImage(Color[] fontcolor,char[] strs,int flag)
{
BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);
//或得图形上下文
//Graphics2D g2d=image.createGraphics();
Graphics2D g2d = (Graphics2D)image.getGraphics();
//利用指定颜色填充背景
g2d.setColor(Color.WHITE);
g2d.fillRect(0, 0, width, height);
AlphaComposite ac3;
int h = height - ((height - font.getSize()) >>1) ;
int w = width/len;
g2d.setFont(font);
for(int i=0;i<len;i++)
{
ac3 = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, getAlpha(flag, i));
g2d.setComposite(ac3);
g2d.setColor(fontcolor[i]);
g2d.drawOval(num(width), num(height), 5+num(10), 5+num(10));
g2d.drawString(strs[i]+"", (width-(len-i)*w)+(w-font.getSize())+1, h-4);
}
g2d.dispose();
return image;
}
/**
* 获取透明度,从0到1,自动计算步长
* @return float 透明度
*/
private float getAlpha(int i,int j)
{
int num = i+j;
float r = (float)1/len,s = (len+1) * r;
return num > len ? (num *r - s) : num * r;
}
}