java 验证码生成详解编程语言

验证码效果图

import java.awt.Color; 
import java.awt.Font; 
import java.io.IOException; 
import java.io.OutputStream; 
import java.util.ArrayList; 
import java.util.List; 
 
import javax.imageio.ImageIO; 
import javax.servlet.Servlet; 
import javax.servlet.ServletException; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
 
import org.apache.commons.lang.math.RandomUtils; 
 
import nl.captcha.Captcha; 
import nl.captcha.Captcha.Builder; 
import nl.captcha.gimpy.BlockGimpyRenderer; 
import nl.captcha.text.producer.ChineseTextProducer; 
import nl.captcha.text.producer.DefaultTextProducer; 
import nl.captcha.text.renderer.DefaultWordRenderer; 
import nl.captcha.text.renderer.WordRenderer; 
 
 
 
public class CaptchaServlet extends HttpServlet implements Servlet { 
	private static final long serialVersionUID = 1L; 
	private static final String PARAM_HEIGHT = "height"; // 高度 默认为50 
 
	private static final String PARAM_WIDTH = "width";// 宽度 默认为200 
 
	private static final String PAEAM_NOISE = "noise";// 干扰线条 默认是没有干扰线条 
 
	private static final String PAEAM_TEXT = "text";// 文本 
 
	protected int _width = 150; 
	protected int _height = 40; 
	protected boolean _noise = false; 
	protected String _text = "number:1,word:1,number:1,number:1,word:1"; 
 
	/** 
	 * 初始化过滤器.将配置文件的参数文件赋值 
	 *  
	 * @throws ServletException 
	 */ 
	@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)); 
		} 
 
		if (getInitParameter(PAEAM_NOISE) != null) { 
			_noise = Boolean.valueOf(getInitParameter(PAEAM_NOISE)); 
		} 
 
		if (getInitParameter(PAEAM_NOISE) != null) { 
			_text = String.valueOf(getInitParameter(PAEAM_TEXT)); 
		} 
	} 
 
	/** 
	 * 因为获取图片只会有get方法 
	 */ 
	@Override 
	public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { 
 
		Builder builder = new Captcha.Builder(_width, _height); 
		// 增加边框 
		// builder.addBorder(); 
		// 是否增加干扰线条 
		if (_noise == true) { 
			builder.addNoise(); 
		} 
		// ----------------自定义字体大小----------- 
		// 自定义设置字体颜色和大小 最简单的效果 多种字体随机显示 
		List<Font> fontList = new ArrayList<Font>(); 
		fontList.add(new Font("微软 雅黑", Font.LAYOUT_NO_START_CONTEXT, 30));// 可以设置斜体之类的 
		DefaultWordRenderer dwr = new DefaultWordRenderer(getRandomColor(), fontList); 
		// 加入多种颜色后会随机显示 字体空心 
 
		WordRenderer wr = dwr; 
		// 增加文本，默认为5个随机字符. 
		if (_text == null) { 
			builder.addText(); 
		} else { 
			String[] ts = _text.split(","); 
			for (int i = 0; i < ts.length; i++) { 
				String[] ts1 = ts[i].split(":"); 
				if ("chinese".equals(ts1[0])) { 
					builder.addText(new ChineseTextProducer(Integer.parseInt(ts1[1])), wr); 
				} else if ("number".equals(ts1[0])) { 
					// 这里没有0和1是为了避免歧义 和字母I和O 
					char[] numberChar = new char[] { '2', '3', '4', '5', '6', '7', '8' }; 
					builder.addText(new DefaultTextProducer(Integer.parseInt(ts1[1]), numberChar), wr); 
				} else if ("word".equals(ts1[0])) { 
					// 原理同上 
					char[] numberChar = new char[] { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'k', 'm', 'n', 'p', 'r', 
							'w', 'x', 'y' }; 
					builder.addText(new DefaultTextProducer(Integer.parseInt(ts1[1]), numberChar), wr); 
				} else { 
					builder.addText(new DefaultTextProducer(Integer.parseInt(ts1[1])), wr); 
				} 
			} 
 
		} 
 
		// --------------添加背景------------- 
		// 设置背景渐进效果 以及颜色 form为开始颜色，to为结束颜色 
		// GradiatedBackgroundProducer gbp=new GradiatedBackgroundProducer(); 
		// gbp.setFromColor(Color.yellow); 
		// gbp.setToColor(Color.red); 
		// 无渐进效果，只是填充背景颜色 
		// FlatColorBackgroundProducer fbp=new 
		// FlatColorBackgroundProducer(Color.red); 
		// 加入网纹--一般不会用 
		// SquigglesBackgroundProducer sbp=new SquigglesBackgroundProducer(); 
		// 没发现有什么用,可能就是默认的 
		// TransparentBackgroundProducer tbp = new 
		// TransparentBackgroundProducer(); 
 
		// builder.addBackground(gbp); 
		// ---------装饰字体--------------- 
		// 字体边框齿轮效果 默认是3 
		builder.gimp(new BlockGimpyRenderer(1)); 
		// 波纹渲染 相当于加粗 
		// builder.gimp(new RippleGimpyRenderer()); 
		// 修剪--一般不会用 
		// builder.gimp(new ShearGimpyRenderer(Color.red)); 
		// 加网--第一个参数是横线颜色，第二个参数是竖线颜色 
		// builder.gimp(new FishEyeGimpyRenderer(Color.red,Color.yellow)); 
		// 加入阴影效果 默认3，75 
		// builder.gimp(new DropShadowGimpyRenderer()); 
		// 创建对象 
		Captcha captcha = builder.build(); 
 
		req.getSession().setAttribute("simpleCaptcha", captcha); 
		resp.setHeader("Cache-Control", "private,no-cache,no-store"); 
		resp.setContentType("image/png"); 
		try { 
			OutputStream os = resp.getOutputStream(); 
			ImageIO.write(captcha.getImage(), "png", os); 
			os.close(); 
		} catch (IOException e) { 
			e.printStackTrace(); 
		} 
	} 
 
	public Color getRandomColor() { 
		int n = RandomUtils.nextInt(100); 
 
		if (n % 3 == 1) { 
			return Color.RED; 
		} else if (n % 3 == 2) { 
			return Color.BLUE; 
		} 
		return Color.GREEN; 
	} 
}