J2EE之验证码实现

package cn.itcast.response;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
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 ResponseDemo5 extends HttpServlet {

	private int WIDTH = 120;
	private int HEIGHT = 25;

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

		BufferedImage image = new BufferedImage(WIDTH , HEIGHT , BufferedImage.TYPE_INT_RGB);
		Graphics graphics = image.getGraphics();

		//设置背景色
		setBackgroundColor(graphics);

		//设置边框
		setBorder(graphics);

		//绘制随机线
		drawRandomLine(graphics);

		//绘制随机数字
		drawRandomNum(graphics);
		response.setContentType("image/jpeg");
		ImageIO.write(image, "jpg", response.getOutputStream());
	}

	private void drawRandomNum(Graphics graphics) {
		// TODO Auto-generated method stub
		graphics.setColor(Color.RED);
		graphics.setFont(new Font("楷体", Font.BOLD, 20));
		String base="\u96d5\u864e\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\u5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50" +
				"\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea" +
				"\u4ee5\u4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\u7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979" +
				"\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\u800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0" +
				"\u4e49\u4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\u5403\u505a\u53eb";
		int x = 10;
		for(int i = 0; i < 4; i++)
		{
			String str = base.charAt(new Random().nextInt(base.length())) + "";
			graphics.drawString(str, x, 21);
			x += 28;
		}
	}

	private void drawRandomLine(Graphics graphics) {
		// TODO Auto-generated method stub
		graphics.setColor(Color.GREEN);

		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);

			graphics.setColor(Color.GREEN);
			graphics.drawLine(x1, y1, x2, y2);
		}
	}

	private void setBorder(Graphics graphics) {
		// TODO Auto-generated method stub
		graphics.setColor(Color.BLACK);
		graphics.drawRect(0, 0, WIDTH, HEIGHT);
	}

	private void setBackgroundColor(Graphics graphics) {
		// TODO Auto-generated method stub
		graphics.setColor(Color.WHITE);
		graphics.fillRect(0, 0, WIDTH - 1, HEIGHT - 1);
	}

}