servlet生成图片验证码

package cn.itcast.servlet.session.demo3;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

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

/**
 * 使用昨天编写代码生成 验证码
 * 
 * @author seawind
 * 
 */
public class CheckcodeServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		int width = 120;
		int height = 30;
		// 1、创建一张 内存中缓冲图片
		BufferedImage bufferedImage = new BufferedImage(width, height,
				BufferedImage.TYPE_INT_RGB);

		// 2、背景色
		Graphics graphics = bufferedImage.getGraphics(); // 通过 graphics对象 绘制图片
		// 设置颜色
		graphics.setColor(Color.YELLOW);
		graphics.fillRect(0, 0, width, height);

		// 3、边框
		graphics.setColor(Color.BLUE);
		graphics.drawRect(0, 0, width - 1, height - 1);

		// 4、写验证码内容
		Graphics2D graphics2d = (Graphics2D) bufferedImage.getGraphics();
		graphics2d.setColor(Color.RED);
		// 设置字体
		graphics2d.setFont(new Font("宋体", Font.BOLD, 18));
		// String content =
		// "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";
		String content = "u7684u4e00u4e86u662fu6211u4e0du5728u4ebau4eecu6709u6765u4ed6u8fd9u4e0au7740u4e2au5730u5230u5927u91ccu8bf4u5c31u53bbu5b50u5f97u4e5fu548cu90a3u8981u4e0bu770bu5929u65f6u8fc7u51fau5c0fu4e48u8d77u4f60u90fdu628au597du8fd8u591au6ca1u4e3au53c8u53efu5bb6u5b66u53eau4ee5u4e3bu4f1au6837u5e74u60f3u751fu540cu8001u4e2du5341u4eceu81eau9762u524du5934u9053u5b83u540eu7136u8d70u5f88u50cfu89c1u4e24u7528u5979u56fdu52a8u8fdbu6210u56deu4ec0u8fb9u4f5cu5bf9u5f00u800cu5df1u4e9bu73b0u5c71u6c11u5019u7ecfu53d1u5de5u5411u4e8bu547du7ed9u957fu6c34u51e0u4e49u4e09u58f0u4e8eu9ad8u624bu77e5u7406u773cu5fd7u70b9u5fc3u6218u4e8cu95eeu4f46u8eabu65b9u5b9eu5403u505au53ebu5f53u4f4fu542cu9769u6253u5462u771fu5168u624du56dbu5df2u6240u654cu4e4bu6700u5149u4ea7u60c5u8defu5206u603bu6761u767du8bddu4e1cu5e2du6b21u4eb2u5982u88abu82b1u53e3u653eu513fu5e38u6c14u4e94u7b2cu4f7fu5199u519bu5427u6587u8fd0u518du679cu600eu5b9au8bb8u5febu660eu884cu56e0u522bu98deu5916u6811u7269u6d3bu90e8u95e8u65e0u5f80u8239u671bu65b0u5e26u961fu5148u529bu5b8cu5374u7ad9u4ee3u5458u673au66f4u4e5du60a8u6bcfu98ceu7ea7u8ddfu7b11u554au5b69u4e07u5c11u76f4u610fu591cu6bd4u9636u8fdeu8f66u91cdu4fbfu6597u9a6cu54eau5316u592au6307u53d8u793eu4f3cu58ebu8005u5e72u77f3u6ee1u65e5u51b3u767eu539fu62ffu7fa4u7a76u5404u516du672cu601du89e3u7acbu6cb3u6751u516bu96beu65e9u8bbau5417u6839u5171u8ba9u76f8u7814u4ecau5176u4e66u5750u63a5u5e94u5173u4fe1u89c9u6b65u53cdu5904u8bb0u5c06u5343u627eu4e89u9886u6216u5e08u7ed3u5757u8dd1u8c01u8349u8d8au5b57u52a0u811au7d27u7231u7b49u4e60u9635u6015u6708u9752u534au706bu6cd5u9898u5efau8d76u4f4du5531u6d77u4e03u5973u4efbu4ef6u611fu51c6u5f20u56e2u5c4bu79bbu8272u8138u7247u79d1u5012u775bu5229u4e16u521au4e14u7531u9001u5207u661fu5bfcu665au8868u591fu6574u8ba4u54cdu96eau6d41u672au573au8be5u5e76u5e95u6df1u523bu5e73u4f1fu5fd9u63d0u786eu8fd1u4eaeu8f7bu8bb2u519cu53e4u9ed1u544au754cu62c9u540du5440u571fu6e05u9633u7167u529eu53f2u6539u5386u8f6cu753bu9020u5634u6b64u6cbbu5317u5fc5u670du96e8u7a7fu5185u8bc6u9a8cu4f20u4e1au83dcu722cu7761u5174u5f62u91cfu54b1u89c2u82e6u4f53u4f17u901au51b2u5408u7834u53cbu5ea6u672fu996du516cu65c1u623fu6781u5357u67aau8bfbu6c99u5c81u7ebfu91ceu575au7a7au6536u7b97u81f3u653fu57ceu52b3u843du94b1u7279u56f4u5f1fu80dcu6559u70edu5c55u5305u6b4cu7c7bu6e10u5f3au6570u4e61u547cu6027u97f3u7b54u54e5u9645u65e7u795eu5ea7u7ae0u5e2eu5566u53d7u7cfbu4ee4u8df3u975eu4f55u725bu53d6u5165u5cb8u6562u6389u5ffdu79cdu88c5u9876u6025u6797u505cu606fu53e5u533au8863u822cu62a5u53f6u538bu6162u53d4u80ccu7ec6";

		// 内容四个字 --- 随机从content中抽取四个字
		Random random = new Random();
		int x = 10;
		int y = 20;
<span style="white-space:pre">		</span>

<span style="white-space:pre">		</span>
		<span style="color:#ff0000;">StringBuffer stringBuffer = new StringBuffer();</span>

		for (int i = 0; i < 4; i++) { // 循环四次
			// 为字 生成旋转角度 -30 ---- 30
			double jiaodu = random.nextInt(60) - 30;
			// 将旋转角度 换算弧度
			double theta = jiaodu / 180 * Math.PI;
			System.out.println(theta);

			int index = random.nextInt(content.length());
			char letter = content.charAt(index); // letter 验证码内容

			stringBuffer.append(letter);

			graphics2d.rotate(theta, x, y);
			graphics2d.drawString(letter + "", x, y);
			// 将角度还原
			graphics2d.rotate(-theta, x, y);
			x += 30;
		}

		<span style="color:#ff0000;">// 将StringBuffer中四个字 转换 String
		String checkcode = stringBuffer.toString();
		// 将验证码存入session
		request.getSession().setAttribute("checkcode_session", checkcode);</span>

		// 5 绘制随机干扰线
		int x1;
		int x2;
		int y1;
		int y2;
		graphics.setColor(Color.LIGHT_GRAY);
		for (int i = 0; i < 10; i++) {
			x1 = random.nextInt(width);
			x2 = random.nextInt(width);
			y1 = random.nextInt(height);
			y2 = random.nextInt(height);
			// 根据两点 绘制直线
			graphics.drawLine(x1, y1, x2, y2);
		}

		// 内存中资源 释放
		graphics.dispose();

		// 将图片输出到 浏览器 ImageIO
		// 将内存的图片 通过 浏览器输出流 写成 jpg格式图片
		ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

}