makecertpic.java

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package util;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
/**
 * @author dzy
 * 生成验证码图片
 */
public class makeCertPic {
    //验证码图片中可以出现的字符集,可根据需要修改
    private char mapTable[]={
    		'a','b','c','d','e','f',
    		'g','h','i','j','k','l',
    		'm','n','o','p','q','r',
    		's','t','u','v','w','x',
    		'y','z','0','1','2','3',
    		'4','5','6','7','8','9'};
    /**
     * 功能:生成彩色验证码图片
     * 参数width为生成的图片的宽度,参数height为生成的图片的高度,参数os为页面的输出流
     */
    public String getCertPic(int width, int height, OutputStream os) {
		if(width<=0)width=60;
		if(height<=0)height=20;	
		BufferedImage image = new BufferedImage(width, height, 
									BufferedImage.TYPE_INT_RGB); 
		// 获取图形上下文 
		Graphics g = image.getGraphics(); 
		// 设定背景色 
		g.setColor(new Color(0xDCDCDC)); 
		g.fillRect(0, 0, width, height); 
		//画边框 
		g.setColor(Color.black); 
		g.drawRect(0,0,width-1,height-1); 
		// 取随机产生的认证码
		String strEnsure = "";
		// 4代表4位验证码,如果要生成更多位的认证码,则加大数值
		for(int i=0; i<4; ++i) {
			strEnsure += mapTable[(int)(mapTable.length*Math.random())];
		}		
		// 将认证码显示到图象中,如果要生成更多位的认证码,增加drawString语句
		g.setColor(Color.black); 
		g.setFont(new Font("Atlantic Inline",Font.PLAIN,18)); 
		String str = strEnsure.substring(0,1); 
		g.drawString(str,8,17); 	
		str = strEnsure.substring(1,2); 
		g.drawString(str,20,15); 
		str = strEnsure.substring(2,3); 
		g.drawString(str,35,18); 		
		str = strEnsure.substring(3,4); 
		g.drawString(str,45,15); 
		// 随机产生10个干扰点
		Random rand = new Random();
		for (int i=0;i<10;i++) { 
			int x = rand.nextInt(width); 
			int y = rand.nextInt(height); 
			g.drawOval(x,y,1,1); 
		} 
		// 释放图形上下文
		g.dispose(); 		
		try {
			// 输出图象到页面 
			ImageIO.write(image, "JPEG", os);
		} catch (IOException e) {
			return "";
		}		
		return strEnsure;
	}
}