介绍一个使用Java代码生成随机图片验证码的示例

可以直接配置成Servlet，在页面直接调用

Java代码随机生成图片验证码

import java.awt.Color;  
  
  
import java.awt.Font;  
import java.awt.Graphics2D;  
import java.awt.image.BufferedImage;  
import java.io.FileOutputStream;  
import java.io.IOException;  
import java.io.OutputStream;  
import java.util.Random;  
  
  
import javax.imageio.ImageIO;  
  
  
/** 
 * 验证码生成器 
 */  
public class ValidateCode {  
  
// 图片的宽度。  
private int width = 160;  
// 图片的高度。  
private int height = 40;  
// 验证码字符个数  
private int codeCount = 5;  
// 验证码干扰线数  
private int lineCount = 150;  
// 验证码  
private static String code = null;  
// 验证码图片Buffer  
private BufferedImage buffImg=null;  
  
  
private char[] codeSequence = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J','K', 'L',   
'M', 'N',  'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W','X', 'Y',   
'Z',  '1', '2', '3', '4', '5', '6', '7', '8', '9' };  
  
  
public  ValidateCode() {  
this.createCode();  
}  
  
  
/** 
*  
* @param width 图片宽 
* @param height 图片高 
*/  
public  ValidateCode(int width,int height) {  
this.width=width;  
this.height=height;  
this.createCode();  
}  
  
/** 
*  
* @param width 图片宽 
* @param height 图片高 
* @param codeCount 字符个数 
* @param lineCount 干扰线条数 
*/  
public  ValidateCode(int width,int height,int codeCount,int lineCount) {  
this.width=width;  
this.height=height;  
this.codeCount=codeCount;  
this.lineCount=lineCount;  
this.createCode();  
}  
  
public void createCode() {  
int x = 0,fontHeight=0,codeY=0;  
int red = 0, green = 0, blue = 0;  
  
x = width / (codeCount +2);//每个字符的宽度  
fontHeight = height - 2;//字体的高度  
codeY = height - 4;  
  
// 图像buffer  
buffImg = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);  
Graphics2D g = buffImg.createGraphics();  
// 生成随机数  
Random random = new Random();  
// 将图像填充为白色  
g.setColor(Color.WHITE);  
g.fillRect(0, 0, width, height);  
// 创建字体  
ImgFontByte imgFont=new ImgFontByte();  
Font font =imgFont.getFont(fontHeight);  
g.setFont(font);  
  
for (int i = 0; i < lineCount; i++) {  
int xs = random.nextInt(width);  
int ys = random.nextInt(height);  
int xe = xs+random.nextInt(width/8);  
int ye = ys+random.nextInt(height/8);  
red = random.nextInt(255);  
green = random.nextInt(255);  
blue = random.nextInt(255);  
g.setColor(new Color(red, green, blue));  
g.drawLine(xs, ys, xe, ye);  
}  
  
// randomCode记录随机产生的验证码  
StringBuffer randomCode = new StringBuffer();  
// 随机产生codeCount个字符的验证码。  
for (int i = 0; i < codeCount; i++) {  
String strRand = String.valueOf(codeSequence[random.nextInt(codeSequence.length)]);  
// 产生随机的颜色值，让输出的每个字符的颜色值都将不同。  
red = random.nextInt(255);  
green = random.nextInt(255);  
blue = random.nextInt(255);  
g.setColor(new Color(red, green, blue));  
g.drawString(strRand, (i + 1) * x, codeY);  
// 将产生的四个随机数组合在一起。  
randomCode.append(strRand);  
}  
// 将四位数字的验证码保存到Session中。  
code = randomCode.toString();  
}  
  
public void write(String path) throws IOException {  
OutputStream sos = new FileOutputStream(path);  
this.write(sos);  
}  
  
public void write(OutputStream sos) throws IOException {  
ImageIO.write(buffImg, "png", sos);  
sos.close();  
}  
  
public BufferedImage getBuffImg() {  
return buffImg;  
}  
  
public static String getCode() {  
return code;  
}  
  
}  

在 servlet 中使用该类：

  
import java.io.IOException;  
  
  
import javax.servlet.ServletException;  
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
import javax.servlet.http.HttpSession;  
  
  
public class ValidateCodeServlet extends HttpServlet {  
  
private static final long serialVersionUID = 1L;  
  
  
protected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {  
response.setContentType("image/jpeg");  
response.setHeader("Pragma", "no-cache");  
response.setHeader("Cache-Control", "no-cache");  
response.setDateHeader("Expires", 0);  
ValidateCode vCode = new ValidateCode(100,30,4,100);  
HttpSession session = request.getSession();  
session.removeAttribute("validateCode");  
vCode.write(response.getOutputStream());  
session.setAttribute("validateCode", vCode.getCode());  
vCode.write(response.getOutputStream());  
}  
  
}  

在 web.xml配置Servlet访问路径：

    <servlet>  
    <servlet-name>validateCodeServlet</servlet-name>  
    <servlet-class>com.rchm.util.images.ValidateCodeServlet</servlet-class>  
    </servlet>   
    <servlet-mapping>  
    <servlet-name>validateCodeServlet</servlet-name>  
    <url-pattern>code.images</url-pattern>