使用Servlet实现注册网页的随机认证图片

在注册帐号的时候，经常出现那种随机认证图片，每次刷新都会变化而且有些干扰和旋转功能，防止恶意注册，但是这个东西到底是怎么做的呢，下面使用Servlet来实现这个功能，其实很简单，一个Servlet搞定，下面是上代码

package com.bird.ServletResponse;

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;

public class ResponseImage extends HttpServlet {

	/**
	 * @use 实现随机图片的生成
	 * @author Bird
	 */
	private static final long serialVersionUID = 1L;
	
	private static final int WIDTH = 120;
	private static final int HEIGHT = 35;
	
	
	
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		//在内出中创建一个图片
		BufferedImage image = new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_INT_RGB);
		Graphics g = image.getGraphics();//得到图形
		
		//1.设置背景颜色
		setBackGound(g);
		
		//2.设置边框
		setBorder(g);
		
		//3.画干扰线
		drwaRandomLine(g);
		
		//4.写随机数
		drawRandomNum((Graphics2D)g);
		
		//5.写给浏览器
		response.setContentType("image/jpeg");//设置浏览器打开方式
		response.setDateHeader("expries", -1);//设置他们不用Cache
		response.setHeader("Cache-Control", "no-cache");
		response.setHeader("Pragma", "no-cache");
		ImageIO.write(image, "jpg", response.getOutputStream());
	}

	private void drawRandomNum(Graphics2D g) {
		
		g.setColor(Color.RED);
		g.setFont(new Font("宋体",Font.BOLD,20));
		
		String base = "\u7684\u4e00\u662f\u6621\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a";
		//所有汉字在\u4e00---\u9fa5
		int x = 5;
		for(int i = 0; i < 4; i++){
			int degree = new Random().nextInt()%30;//旋转弧度
			String ch = base.charAt(new Random().nextInt(base.length()))+"";
			g.rotate(degree*Math.PI/180, x, 20);//设置旋转弧度
	//		System.out.println(ch+"\n");
			g.drawString(ch, x, 20);
			g.rotate(-degree*Math.PI/180, x, 20);//旋转回来才能进行下次旋转
			x+=30;
		}
		
		
	}

	private void drwaRandomLine(Graphics g) {
		g.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);
			
			g.drawLine(x1, y1, x2, y2);
		}
		
	}

	private void setBorder(Graphics g) {
		g.setColor(Color.BLUE);
		g.drawRect(1, 1, WIDTH-2, HEIGHT-2);
	}

	private void setBackGound(Graphics g) {
		g.setColor(Color.WHITE);
		g.fillRect(0, 0, WIDTH, HEIGHT);
	}

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

	}
	
	

}

然后写到一个网页上面去，当然，没有任何修饰，见笑

最终效果如下