实例（2）----------struts2验证码

1、工具类

SecurityCode.java

package com.baizhi.util;

import java.util.Arrays;

/**
 * 
 * @author others
 * date:2014-8-26  下午2:17:19
 * 描述：随机生成验证码值：验证码串
 */
public class SecurityCode {
	/**
	 * 验证码难度级别
	 *   Simple-数字
	 *   Medium-数字和小写字母 
	 *   Hard-数字和大小写字母
	 */
	public enum SecurityCodeLevel {
		Simple, Medium, Hard
	};
	/**
	 * 产生默认验证码，4位中等难度
	 *
	 * @return
	 */
	public static String getSecurityCode() {
		return getSecurityCode(4, SecurityCodeLevel.Medium, false);
	}
	/**
	 * 产生长度和难度任意的验证码
	 *
	 * @param length
	 * @param level
	 * @param isCanRepeat
	 * @return
	 */
	private static String getSecurityCode(int length, SecurityCodeLevel level, boolean isCanRepeat) {
		// 随机抽取len个字符
		int len = length;
		// 字符集合（--除去易混淆的数字0,1,字母l,o,O）
		char[] codes = {
				'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
				'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',
				'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'
		};
		// 根据不同难度截取字符串
		if (level == SecurityCodeLevel.Simple) {
			codes = Arrays.copyOfRange(codes, 0, 10);
		} else if (level == SecurityCodeLevel.Medium) {
			codes = Arrays.copyOfRange(codes, 0, 36);
		}
		// 字符集和长度
		int n = codes.length;
		// 抛出运行时异常
		if (len > n && isCanRepeat == false) {
			throw new RuntimeException(String.format("调用SecurityCode.getSecurityCode(%1$s,%2$s,%3$s)出现异常，" + "当isCanRepeat为%3$s时，传入参数%1$s不能大于%4$s", len, level, isCanRepeat, n));
		}
		// 存放抽取出来的字符
		char[] result = new char[len];
		// 判断能否出现重复字符
		if (isCanRepeat) {
			for (int i = 0; i < result.length; i++) {
				// 索引0 and n-1
				int r = (int) (Math.random() * n);
				// 将result中的第i个元素设置为code[r]存放的数值
				result[i] = codes[r];
			}
		} else {
			for (int i = 0; i < result.length; i++) {
				// 索引0 and n-1
				int r = (int) (Math.random() * n);
				// 将result中的第i个元素设置为code[r]存放的数值
				result[i] = codes[r];
				// 必须确保不会再次抽取到那个字符，这里用数组中最后一个字符改写code[r],并将n-1
				codes[r] = codes[n - 1];
				n--;
			}
		}
		return String.valueOf(result);
	}
	public static void main(String[] args) {
		System.out.println(SecurityCode.getSecurityCode());
	}
}

SecurityImage.java

package util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.util.Random;

public class SecurityImage {
    /**
     * 生成验证码图片

     * @param securityCode

     * @return

     */
    public static BufferedImage createImage(String securityCode){

        int codeLength = securityCode.length();//验证码长度
        
        int fontSize = 15;//字体大小

        int fontWidth = fontSize+1;

        //图片宽高

        int width = codeLength*fontWidth+6;

        int height = fontSize*2+1;

        //图片

        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        //画板
        Graphics2D g = image.createGraphics();

        g.setColor(Color.WHITE);//设置背景色

        g.fillRect(0, 0, width, height);//填充背景
        
        g.setColor(Color.LIGHT_GRAY);//设置边框颜色

        g.setFont(new Font("Arial", Font.BOLD, height-2));//边框字体样式

        g.drawRect(0, 0, width-1, height-1);//绘制边框

        //绘制噪点

        Random rand = new Random();

        g.setColor(Color.LIGHT_GRAY);

        for (int i = 0; i < codeLength*6; i++) {

            int x = rand.nextInt(width);

            int y = rand.nextInt(height);

            g.drawRect(x, y, 1, 1);//绘制1*1大小的矩形

        }

        //绘制验证码

        int codeY = height-10;

        g.setColor(new Color(19,148,246));

        g.setFont(new Font("Georgia", Font.BOLD, fontSize));
        for(int i=0;i<codeLength;i++){
        	double deg=new Random().nextDouble()*20;
        	g.rotate(Math.toRadians(deg), i*16+13,codeY-7.5);
            g.drawString(String.valueOf(securityCode.charAt(i)), i*16+5, codeY);
            g.rotate(Math.toRadians(-deg), i*16+13,codeY-7.5);
        }
       
        g.dispose();//关闭资源

        return image;

    }     

}

login.jsp

<%@ page language="java" import="java.util.*,com.opensymphony.xwork2.ActionContext" pageEncoding="utf-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
  </head>
  	<title>login</title>
  <body>
    <form action="<s:url value='/user/login'/>" method="post">
    	用户名：<input type="text" name="username"/><br/>
    	密码：<input type="text" name="password"/><br/>
    	验证码：<input type="text" name="yz"> <img src="<s:url value="/util/code"/>"/> 
    	<br/><input type="submit" value="登陆" />
    </form>
    <a href="regist.jsp">注册</a>
  </body>
</html>

UtilAction.java

package com.baizhi.action;

import java.awt.image.BufferedImage;
import java.io.IOException;

import javax.imageio.ImageIO;

import org.apache.struts2.ServletActionContext;

import com.baizhi.util.SecurityCode;
import com.baizhi.util.SecurityImage;
import com.opensymphony.xwork2.Action;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;

public class UtilAction extends ActionSupport{
	public String code() throws IOException{
		//获取验证码
		String sc = SecurityCode.getSecurityCode();
		//添加到图片
		BufferedImage createImage = SecurityImage.createImage(sc);
		//加入session
		ActionContext.getContext().getValueStack().setValue("#session.code", sc);
		ImageIO.write(createImage, "png", ServletActionContext.getResponse().getOutputStream());
		
		return Action.NONE;
	}
}

struts.xml

	</package>
	<package name="util" namespace="/util" extends="struts-default">
		<action name="code" class="com.baizhi.action.UtilAction" method="code"/>
	</package>

运行截图