Java EE登陆界面生成随机数防止恶意注册或者登录
package cn.com;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 ResponseDemoRandom extends HttpServlet {private static final long serialVersionUID = 1L;public static final int WIDTH=120;public static final int HEIGHT=25;protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {BufferedImage image=new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_INT_RGB);Graphics g=image.getGraphics();//设置背景色setBackGround(g);//设置边框setBorder(g);//画干扰线drawRandomLine(g);//写随机数drawRandomNum((Graphics2D)g);response.setContentType("image/jpeg");response.setDateHeader("expries", -1);response.setHeader("Cache-Control", "no-control");response.setHeader("prama", "no-control");ImageIO.write(image, "jpg", response.getOutputStream());}private void drawRandomNum(Graphics2D g) {g.setColor(Color.PINK);g.setFont(new Font("宋体",Font.BOLD,20));int x=10;for(int i=0;i<4;i++){int degree=new Random().nextInt()%30;int num=new Random().nextInt(9);String str=num+"";g.rotate(degree*Math.PI/180, x, 20);g.drawString(str, x, 20);g.rotate(-degree*Math.PI/180, x, 20);x+=30;}}private void drawRandomLine(Graphics g) {g.setColor(Color.blue);for(int i=0;i<5;i++){int x1=new Random().nextInt(WIDTH-4)+2;int y1=new Random().nextInt(HEIGHT-4)+2;int x2=new Random().nextInt(WIDTH-2);int y2=new Random().nextInt(HEIGHT-2);g.drawLine(x1, y1, x2, y2);}}private void setBorder(Graphics g) {g.setColor(Color.GREEN);g.drawRect(1, 1, WIDTH-2, HEIGHT-2);}private void setBackGround(Graphics g) {g.setColor(Color.gray);g.fillRect(0, 0, WIDTH, HEIGHT);}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}}