imagecaptchaservlet.java

JEECMS是JavaEE版网站管理系统（Java Enterprise Edition Content Manage System）的简称。 基于java技术开发

package com.ponyjava.common.checkcode;

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

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

import com.octo.captcha.service.CaptchaServiceException;
import com.octo.captcha.service.image.ImageCaptchaService;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

@SuppressWarnings("serial")
public class ImageCaptchaServlet extends HttpServlet {
	private ImageCaptchaService imageCaptchaService;
	private String beanName = "imageCaptchaService";

	public void init(ServletConfig servletConfig) throws ServletException {
		super.init(servletConfig);
		WebApplicationContext wac = WebApplicationContextUtils
				.getRequiredWebApplicationContext(servletConfig
						.getServletContext());
		imageCaptchaService = (ImageCaptchaService) wac.getBean(beanName,
				ImageCaptchaService.class);
	}

	protected void doGet(HttpServletRequest httpServletRequest,
			HttpServletResponse httpServletResponse) throws ServletException,
			IOException {

		byte[] captchaChallengeAsJpeg = null;
		// the output stream to render the captcha image as jpeg into
		ByteArrayOutputStream jpegOutputStream = new ByteArrayOutputStream();
		try {
			// get the session id that will identify the generated captcha.
			// the same id must be used to validate the response, the session id
			// is a good candidate!
			String captchaId = httpServletRequest.getSession().getId();
			// call the ImageCaptchaService getChallenge method
			BufferedImage challenge = imageCaptchaService
					.getImageChallengeForID(captchaId, httpServletRequest
							.getLocale());

			// a jpeg encoder
			JPEGImageEncoder jpegEncoder = JPEGCodec
					.createJPEGEncoder(jpegOutputStream);
			jpegEncoder.encode(challenge);
		} catch (IllegalArgumentException e) {
			httpServletResponse.sendError(HttpServletResponse.SC_NOT_FOUND);
			return;
		} catch (CaptchaServiceException e) {
			httpServletResponse
					.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
			return;
		}

		captchaChallengeAsJpeg = jpegOutputStream.toByteArray();

		// flush it in the response
		httpServletResponse.setHeader("Cache-Control", "no-store");
		httpServletResponse.setHeader("Pragma", "no-cache");
		httpServletResponse.setDateHeader("Expires", 0);
		httpServletResponse.setContentType("image/jpeg");
		ServletOutputStream responseOutputStream = httpServletResponse
				.getOutputStream();
		responseOutputStream.write(captchaChallengeAsJpeg);
		responseOutputStream.flush();
		responseOutputStream.close();
	}
}