java验证码图片

package com.su.servlet;

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.ArrayList;
import java.util.List;
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;

public class CheckCode  extends HttpServlet{

	/**
	 *
	 */
	private static final long serialVersionUID = 1L;

	public static final int WIDTH = 120;//生成图片的宽度
	public static final int HEIGHT = 30;//生成图片的高度

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

	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		request.setCharacterEncoding("utf-8");

	    //在内存中创建一张图片
		BufferedImage bi = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);

       //得到图片
		Graphics graphics = bi.getGraphics();

       //设置图片的背景色
		graphics.setColor(Color.white);
		graphics.fillRect(0, 0, WIDTH, WIDTH);

		//设置图片的边框
		graphics.setColor(Color.RED);
		graphics.drawRect(1, 1, WIDTH-2, HEIGHT-2);
		Color[] color={Color.BLACK,Color.BLUE,Color.CYAN,Color.GREEN,       //定义颜色数组
				Color.ORANGE,Color.YELLOW,Color.RED,Color.PINK,Color.LIGHT_GRAY};
		//图片上画干扰线
		graphics.setColor(Color.BLUE);
		//设置线条个数并画线
		for(int i=0;i<10;i++){
			graphics.setColor(color[new Random().nextInt(9)]);
			int x1 = new Random().nextInt(WIDTH);
			int x2 = new Random().nextInt(WIDTH);
			int y1 = new Random().nextInt(HEIGHT);
			int y2 = new Random().nextInt(HEIGHT);
			graphics.drawLine(x1, y1, x2, y2);
		}

		StringBuilder sb = new StringBuilder();

		//把随机数写在图片上
		graphics.setColor(Color.GRAY);
		graphics.setFont(new Font("楷体", Font.BOLD, 20));

		 Graphics2D g = (Graphics2D)graphics;
		 // 控制字数

		String str ="0123456789ABCDEFGHIGKLMNOPQRSTUVWRST";

		int x = 5;
		  for (int i = 0; i < 4; i++) {
		          // 设置字体旋转角度
	              int degree = new Random().nextInt() % 30;
	              char ch = str.charAt(new Random().nextInt(36));
		          sb.append(String.valueOf(ch));
		          // 正向角度
		          g.rotate(degree * Math.PI / 180, x, 20);
		          graphics.drawString(String.valueOf(ch), x, 20);
		         // 反向角度
		         g.rotate(-degree * Math.PI / 180, x, 20);
		          x += 30;
		        }

		//7.将随机数存在session中
		request.getSession().setAttribute("checkCode", sb.toString());
		//8.设置响应头通知浏览器以图片的形式打开
		response.setContentType("image/jpeg");
		//9.设置响应头控制浏览器不要缓存
		response.setDateHeader("expries", -1);
		response.setHeader("Cache-Control", "no-cache");
		response.setHeader("Pragma", "no-cache");
		//10.将图片写给浏览器
		ImageIO.write(bi, "jpg", response.getOutputStream());

	}

}