Servlet 获取的随机图片验证码制作

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;
/**
 *  获取随机验证码（图片）,防止恶意访问
 *  @author lu
 *  @version 1.0
 */
public class ImageServlet extends HttpServlet {
	private static final long serialVersionUID = 4172288020211199830L;
	public static final int WIDTH = 190;
	public static final int HEIGHT = 50;
	public void doGet(HttpServletRequest request, HttpServletResponse response)
	throws ServletException, IOException {
		response.setContentType("image/jpeg");
		BufferedImage image = new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_INT_RGB);
		Graphics g= image.getGraphics();
		setBackGroud(g);
		setBorder(g);
		drawRandomLine(g);
		String random=drawRandomNum((Graphics2D)g);
		request.getSession().setAttribute("checkCode",random);
		//控制浏览器不缓存验证码
		response.setDateHeader("expries",-1);
		response.setHeader("Cache-Control","no-cache");
		response.setHeader("Prama","no-cache");
		ImageIO.write(image,"jpg", response.getOutputStream());
	}
	//设置随机字符
	private String drawRandomNum(Graphics2D g) {
		g.setColor(Color.WHITE);
		g.setFont(new Font("楷体",Font.BOLD,30));
		String base="\u7684\u4e00\u4e86\u662f\u66211\u4e0d\u5728\u4eba\u4eec\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u41fa" +
				"\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762";
		StringBuffer sb = new StringBuffer();
		int x=20;
		for(int i=0;i<=3;i++) {
			int degree = new Random().nextInt()%30;
			String ch = base.charAt(new Random().nextInt(base.length()))+"";
			sb.append(ch);
			g.rotate(degree*Math.PI/180,x,35);
			g.drawString(ch,x,35);
			g.rotate(-degree*Math.PI/180,x,35);
			x+=40;
		}
		return sb.toString();
	}
	//设置干扰线
	private void drawRandomLine(Graphics g) {
		g.setColor(Color.WHITE);
		for(int i=0;i<5;i++) {
			int x1=new Random().nextInt(WIDTH);
			int y1=new Random().nextInt(HEIGHT);
			int x2=new Random().nextInt(WIDTH);
			int y2=new Random().nextInt(HEIGHT);
			g.drawLine(x1, y1, x2, y2);
		}
	}
	//设置背景
	private void setBorder(Graphics g) {
		g.setColor(Color.BLACK);
		g.fillRect(2, 2, WIDTH-4, HEIGHT-4);
	}
	//设置边框
	private void setBackGroud(Graphics g) {
		g.setColor(Color.GRAY);
		g.fillRect(0, 0, WIDTH, HEIGHT);
	}
	public void doPost(HttpServletRequest request, HttpServletResponse response)
	throws ServletException, IOException {
		doGet(request,response);
	}
}