simplecaptchaservlet.java

来自「一套用于生成各种图形验证码的库(Java)」· Java 代码 · 共 59 行

package nl.captcha.servlet;

import static nl.captcha.Captcha.NAME;

import java.io.IOException;

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

import nl.captcha.Captcha;
import nl.captcha.backgrounds.GradiatedBackgroundProducer;


/**
 * Generates, displays, and stores in session a 200x50 CAPTCHA image with sheared black text, 
 * a solid dark grey background, and a straight, slanted red line through the text.
 * 
 * @author <a href="mailto:[e-mail]">James Childers</a>
 */
public class SimpleCaptchaServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    private static final String PARAM_HEIGHT = "height";
    private static final String PARAM_WIDTH = "width";

    protected int _width = 200;
    protected int _height = 50;

    @Override
    public void init() throws ServletException {
    	if (getInitParameter(PARAM_HEIGHT) != null) {
    		_height = Integer.valueOf(getInitParameter(PARAM_HEIGHT));
    	}
    	
    	if (getInitParameter(PARAM_WIDTH) != null) {
    		_width = Integer.valueOf(getInitParameter(PARAM_WIDTH));
    	}
    }
    
    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {

        Captcha captcha = new Captcha.Builder(_width, _height)
        	.addText()
        	.addBackground(new GradiatedBackgroundProducer())
            .gimp()
            .addNoise()
            .addBorder()
            .build();

        CaptchaServletUtil.writeImage(resp, captcha.getImage());
        req.getSession().setAttribute(NAME, captcha);
    }
}