인증번호 - 숫자 한자

package com.squirrel.db;

import java.awt.Color;
import java.awt.Font;
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.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * Servlet implementation class VerificationCode
 */
public class VerificationCode extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    public VerificationCode() {
        super();
    }
    //     
    private String zh_codes_str="                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   ";
	//    1，    2，    3
    private int u=1;
    //         。
	private int width = 130;
	//         。
	private int height = 25;
	//        
	private int codeCount = 4;

	private int x = 0;
	//     
	private int fontHeight;
	private int codeY;

	char[] en_num_codes = { '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', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
	
	/**
	 *          
	 */
	public void init() throws ServletException {
		//  web.xml       
		//   
		String strWidth = this.getInitParameter("width");
		//   
		String strHeight = this.getInitParameter("height");
		//     
		String strCodeCount = this.getInitParameter("codeCount");

		//            
		try {
			if (strWidth != null && strWidth.length() != 0) {
				width = Integer.parseInt(strWidth);
			}
			if (strHeight != null && strHeight.length() != 0) {
				height = Integer.parseInt(strHeight);
			}
			if (strCodeCount != null && strCodeCount.length() != 0) {
				codeCount = Integer.parseInt(strCodeCount);
			}
		} catch (NumberFormatException e) {
		}

		x = width / (codeCount + 1);
		fontHeight = height - 2;
		codeY = height - 4;

	}
	
	
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		this.doPost(request,response);
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, java.io.IOException {

		//     buffer
		BufferedImage buffImg = new BufferedImage(width, height,
				BufferedImage.TYPE_INT_RGB);
		Graphics2D g = buffImg.createGraphics();

		//            
		Random random = new Random();

		//         
		g.setColor(Color.WHITE);
		g.fillRect(0, 0, width, height);

		//     ，                。
		Font font = new Font("Fixedsys", Font.PLAIN, fontHeight);
		//     。
		g.setFont(font);

		//    。
		g.setColor(Color.BLACK);
		g.drawRect(0, 0, width - 1, height - 1);

		//     160    ，                  。
		g.setColor(Color.BLACK);
		for (int i = 0; i < 10; i++) {
			int x = random.nextInt(width);
			int y = random.nextInt(height);
			int xl = random.nextInt(12);
			int yl = random.nextInt(12);
			g.drawLine(x, y, x + xl, y + yl);
		}

		// randomCode            ，
		//           。
		StringBuffer randomCode = new StringBuffer();
		int red = 0, green = 0, blue = 0;
		
		//     
		char[]zh_codes=zh_codes_str.toCharArray();
		
		//     codeCount      。
		for (int i = 0; i < codeCount; i++) {
			String simple_code ="a";//        
			switch (u) {
			case 1:
				//   _    。
				simple_code = String.valueOf(en_num_codes[random.nextInt(36)]);
				break;
			case 2:
				//   _    (   )
				simple_code = String.valueOf(zh_codes[random.nextInt(zh_codes.length)]);
				break;
			case 3:
				//   _  。
				simple_code=(char)(random.nextInt(40870-19968)+19968)+"";
				break;
			default:
				break;
			}
			
			//                ，                 。
			red = random.nextInt(255);
			green = random.nextInt(255);
			blue = random.nextInt(255);

			//                   。
			g.setColor(new Color(red, green, blue));
			g.drawString(simple_code, (i + 1) * x, codeY);

			//               。
			randomCode.append(simple_code);
		}
		//             Session 。
		HttpSession session = request.getSession();
		session.setAttribute("VERIFICATIONCODE", randomCode.toString());

		//       。
		response.setHeader("Pragma", "no-cache");
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expires", 0);

		response.setContentType("image/jpeg");

		//       Servlet    。
		ServletOutputStream sos = response.getOutputStream();
		ImageIO.write(buffImg, "jpeg", sos);
		sos.close();
	}

}