web中生成图片认证码的servlet，存到session域中、、、 - 黑马程序员技术交流社区

package yting.day06.web.randompic;
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 ServletRandomPicture extends HttpServlet {
private static final long serialVersionUID = 3096336305189372825L;
private static final int WIDTH = 120;
private static final int HEIGHT = 25;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
BufferedImage image = new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
//1.设置背景色
setBackGround(g);
//2.设置边框
setBorder(g);
//3.画干扰线
drawRandomLine(g);
//4.写随机数
String cilentCheckCode = drawRandowNum((Graphics2D) g);
//将cilentCheckCode存到session中去，用来校验用
request.getSession().setAttribute("checkcode", cilentCheckCode);
//5.图形写给浏览器,通知浏览器以图片的方式打开,并且告诉浏览器不要缓存
response.setHeader("content-type", "image/jpeg");
response.setDateHeader("expries", -1);
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");
ImageIO.write(image, "jpeg", response.getOutputStream());
}
private void setBackGround(Graphics g) {
g.setColor(Color.WHITE);
g.fillRect(0, 0, WIDTH, HEIGHT);
}
private void setBorder(Graphics g) {
g.setColor(Color.BLACK);
g.drawRect(0, 0, WIDTH-1, HEIGHT-1);
}
private void drawRandomLine(Graphics g) {
g.setColor(Color.GREEN);
for(int i=0; i<5; i++){
int x1 = 0;
int y1 = new Random().nextInt(HEIGHT);
int x2 = WIDTH-1;
int y2 = new Random().nextInt(HEIGHT);
g.drawLine(x1, y1, x2, y2);
}
}
private String drawRandowNum(Graphics2D g) {
String str = "最后饿留着眼泪看他抱着你的背我的想念你看不见另一个世界多美最后哭着说再见其实心里不情愿伤心绝对痛彻心扉离开以后饿不会再醉";
StringBuffer sb = new StringBuffer();
g.setColor(Color.RED);
g.setFont(new Font("楷体", Font.BOLD, 25));
int x=5;
for(int i=0;i<4;i++){
int degree = new Random().nextInt()%30; //设置旋转弧度,在-30~30之间
String ch = str.charAt(new Random().nextInt(str.length()))+"";
sb.append(ch);
g.rotate(degree*Math.PI/180, x+14, 11); //开始旋转
g.drawString(ch, x, 22);
g.rotate(-degree*Math.PI/180, x+14, 11); //将旋转的弧度转回去，写下一个字
x+=28;
}
return sb.toString();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}

复制代码