strut2图形验证码

import com.opensymphony.xwork2.ActionSupport;

import java.util.Random;
import java.awt.*;
import java.awt.image.*;
import java.io.ByteArrayOutputStream;

import org.apache.struts2.ServletActionContext;

public class ImageAction extends ActionSupport {

    /**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	/**
     * 验证码对应的Session名
     */

    private static final String SESSIONNAME = "CheckCodeImageAction";

    /**
     * 用于随机生成验证码的数据源
     */
    private static final char[] SOURCECODE = new char[]{
       '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',
       '1', '2', '3', '4', '5', '6', '7', '8', '9', '0'
    };
    /**
     * 用于随机打印验证码的字符颜色
     */
    private static final Color[] COLORS = new Color[]{
       Color.RED, Color.BLUE, Color.BLACK, Color.GREEN, Color.YELLOW, Color.CYAN
    };
    /**
     * 用于打印验证码的字体
     */
    private static final Font FONTCODE = new Font("Times New Roman", Font.ITALIC, 25);
    /**
     * 用于生成随机数的随机数生成器
     */
    private static final Random rdm = new Random();
    private String text = "";
    private byte[] bytes = null;
    private String contentType = "image/png";

    public byte[] getImageBytes(){
       return this.bytes;
    }

    public String getContentType(){
       return this.contentType;
    }

    public void setContentType(String value){
       this.contentType = value;
    }

    public int getContentLength(){
       return bytes.length;
    }

    /**
     * 生成长度为4的随机字符串
     */
    private void generateText(){
       char[] source = new char[4];
       for(int i=0; i<source.length; i++){
           source[i] = ImageAction.SOURCECODE[rdm.nextInt(ImageAction.SOURCECODE.length)];
       }
       this.text = new String(source);
       // 设置Session
       ServletActionContext.getRequest().getSession().setAttribute(SESSIONNAME, this.text);
    }

    /**
     * 在内存中生成打印了随机字符串的图片
     * @return 在内存中创建的打印了字符串的图片
     */
    private BufferedImage createImage(){
       int width = 150;
       int height = 45;

       BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
       Graphics g = image.getGraphics();
       g.setColor(Color.LIGHT_GRAY);
       g.fillRect(0, 0, width, height);
       g.setFont(FONTCODE);
       for(int i=0; i<this.text.length(); i++){
           g.setColor(COLORS[rdm.nextInt(COLORS.length)]);
           g.drawString(this.text.substring(i, i+1), 9 + rdm.nextInt(i + 5) * 11, 45-rdm.nextInt(7)*3 );
       }
       g.dispose();
       return image;
    }

    /**
     * 根据图片创建字节数组
     * @param image 用于创建字节数组的图片
     */
    private void generatorImageBytes(BufferedImage image){
       ByteArrayOutputStream bos = new ByteArrayOutputStream();
       try{
           javax.imageio.ImageIO.write(image, "jpg", bos);
           this.bytes = bos.toByteArray();
       }catch(Exception ex){
    	   ex.printStackTrace();
       }finally{
           try{
              bos.close();
           }catch(Exception ex1){
        	   ex1.printStackTrace();
           }
       }
    }

    /**
     * 被struts2过滤器调用的方法
     * @return 永远返回字符串"image"
     */
    public String getImage(){
       this.generateText();
       BufferedImage image = this.createImage();
       this.generatorImageBytes(image);
       return "image";
    }
}

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

import com.opensymphony.xwork2.ActionInvocation;

import com.opensymphony.xwork2.Result;
import com.rs.learnOnline.action.ImageAction;

import javax.servlet.http.HttpServletResponse;

import org.apache.struts2.ServletActionContext;

public class ImageResult implements Result {
    /**
	 * 
	 */
	private static final long serialVersionUID = 5205515981838231120L;

	public void execute(ActionInvocation ai) throws Exception {

       ImageAction action = (ImageAction)ai.getAction();

       HttpServletResponse response = ServletActionContext.getResponse();

       response.setHeader("Cash", "no cash");

       response.setContentType(action.getContentType());

       response.setContentLength(action.getContentLength());

       response.getOutputStream().write(action.getImageBytes());

       response.getOutputStream().flush();
    }
}

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
<package namespace="/test" name="testPackage" extends="struts-default">
       <result-types>
           <result-type name="ValidateImage" class="com.rs.learnOnline.dao.impl.ImageResult" />
       </result-types>
       <action name="ValidateImage" class="com.rs.learnOnline.action.ImageAction" method="getImage">
           <result name="image" type="ValidateImage" />
       </action>
    </package>

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

function changeValidateCode(obj) {
         //获取当前的时间作为参数，无具体意义
         var timenow = new Date().getTime();
         //每次请求需要一个不同的参数，否则可能会返回同样的验证码
         //可能和浏览器的缓存机制有关系
         obj.src="test/ValidateImage?d="+timenow;
     }


<td align="right">验证图片：</td>
    <td><img id="vfcode" alt="操作频繁,稍后再试" src="test/ValidateImage" onclick="changeValidateCode(this)" title="看不清楚？ 换张图片" /> 
    </td>