struts2生成隨機驗證碼圖片

public class CreateImageAction extends ActionSupport
{
    private ByteArrayInputStream inputStream;

    private static int WIDTH = 60;

    private static int HEIGHT = 20;

    public ByteArrayInputStream getInputStream()
    {
        return inputStream;
    }

    public void setInputStream(ByteArrayInputStream inputStream)
    {
        this.inputStream = inputStream;
    }
private static String createRandom()
    {
        String str = "0123456789qwertyuiopasdfghjklzxcvbnm";

        char[] rands = new char[4];

        Random random = new Random();

        for (int i = 0; i < 4; i++)
        {
            rands[i] = str.charAt(random.nextInt(36));
        }

        return new String(rands);
    }

    private void drawBackground(Graphics g)
    {
        // 畫背景
        g.setColor(new Color(0xDCDCDC));

        g.fillRect(0, 0, WIDTH, HEIGHT);

        // 隨機產生 120 個干擾點

        for (int i = 0; i < 120; i++)
        {
            int x = (int) (Math.random() * WIDTH);

            int y = (int) (Math.random() * HEIGHT);

            int red = (int) (Math.random() * 255);

            int green = (int) (Math.random() * 255);

            int blue = (int) (Math.random() * 255);

            g.setColor(new Color(red, green, blue));

            g.drawOval(x, y, 1, 0);
        }
    }

    private void drawRands(Graphics g, String rands)
    {
        g.setColor(Color.BLACK);

        g.setFont(new Font(null, Font.ITALIC | Font.BOLD, 18));

        // 在不同的高度上輸出驗證碼的每個字元

        g.drawString("" + rands.charAt(0), 1, 17);

        g.drawString("" + rands.charAt(1), 16, 15);

        g.drawString("" + rands.charAt(2), 31, 18);

        g.drawString("" + rands.charAt(3), 46, 16);

        System.out.println(rands);

    }

    @Override
    public String execute() throws Exception
    {
        HttpServletResponse response = ServletActionContext.getResponse();

        // 設定瀏覽器不要快取此圖片
        response.setHeader("Pragma", "no-cache");

        response.setHeader("Cache-Control", "no-cache");

        response.setDateHeader("Expires", 0);

        String rands = createRandom();

        BufferedImage image = new BufferedImage(WIDTH, HEIGHT,
                BufferedImage.TYPE_INT_RGB);

        Graphics g = image.getGraphics();

        // 產生影象
        drawBackground(g);

        drawRands(g, rands);

        // 結束影象 的繪製 過程， 完成影象
        g.dispose();

        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

        ImageIO.write(image, "jpeg", outputStream);

        ByteArrayInputStream input = new ByteArrayInputStream(outputStream
                .toByteArray());

        this.setInputStream(input);

        HttpSession session = ServletActionContext.getRequest().getSession();

        session.setAttribute("checkCode", rands);
        
        input.close();
        
        outputStream.close();

        return SUCCESS;
    }
}

public class LoginValidateAction extends ActionSupport
{
    private String checkCode;
    
    public String getCheckCode()
    {
        return checkCode;
    }

    public void setCheckCode(String checkCode)
    {
        this.checkCode = checkCode;
    }

    @Override
    public String execute() throws Exception
    {
        return SUCCESS;
    }
    
    @Override
    public void validate()
    {
        HttpSession session = ServletActionContext.getRequest().getSession();
        
        String checkCode2 = (String)session.getAttribute("checkCode");
        
        if(!checkCode.equals(checkCode2))
        {
            this.addActionError("輸入的驗證碼不正確，請重新輸入！");
        }
    }
}

　　　　　　<action name="createImageAction" class="com.xiaoluo.action.CreateImageAction">
                <result name="success" type="stream">
                    <param name="contentType">image/jpeg</param>
                    <param name="inputName">inputStream</param>
                </result>
　　　　　　  </action>
            
            <action name="loginValidateAction" class="com.xiaoluo.action.LoginValidateAction">
                <result name="success">/success.jsp</result>
                <result name="input">/login.jsp</result>
            </action>

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'login.jsp' starting page</title>
    
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
    
  </head>
  
  <body>

    <h3><font color="blue">帶有驗證碼的登陸介面</font></h3>
    
    <s:form action="loginValidateAction.action" theme="simple">
    
        使用者名稱:<s:textfield name="username"></s:textfield><br>
        密碼    :<s:password name="password"></s:password><br>
        驗證碼:<s:textfield name="checkCode"></s:textfield>
　　　　　
　　　　　<!--若要點選圖片重新整理，重新得到一個驗證碼，要在後面加上個隨機數，這樣保證每次提交過去的都是不一樣的path，防止因為快取而使圖片不重新整理-->
        <img src="createImageAction.action" onclick="this.src='createImageAction.action?'+ Math.random()" title="點選圖片重新整理驗證碼"/><br>
        <s:actionerror cssStyle="color:red"/>
        
        <s:submit value="提交"></s:submit>
    
    </s:form>

  </body>
</html>