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();
//1、设置背景色
setBackGroud(g);
//2.设置边框
setBorder(g);
//3.画干扰线
drawRandomLine(g);
//4.写随机数
drawRandomNum((Graphics2D)g);
//5.图形写给浏览器
response.setContentType("image/jpeg");
//发图控制浏览器不要缓存
response.setDateHeader("expries", -1);
response.setHeader("cache-control", "no-cache");
response.setHeader("Pragma", "no-cache");
ImageIO.write(image, "jpg", response.getOutputStream());
}
private void setBackGroud(Graphics g) {
g.setColor(Color.WHITE);
//填充矩形
g.fillRect(0, 0, WIDTH, HEIGHT);
}
private void setBorder(Graphics g) {
g.setColor(Color.BLUE);
g.drawRect(1, 1, WIDTH-2, HEIGHT-2);
}
private void drawRandomLine(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 drawRandomNum(Graphics2D g) {
g.setColor(Color.RED);
g.setFont(new Font("宋体",Font.BOLD,20));
//中文字所在区间 [\u4e00-\u9fa5]
String base = "ABCDEFGHIJK";
int x = 10;
for(int i=0; i<4; i++){
//设置旋转角度
int degree = new Random().nextInt()%30;//生成正负30内数
String ch = base.charAt(new Random().nextInt(base.length()))+"";
g.rotate(degree*Math.PI/180, x, 20);
g.drawString(ch, x, 20);
g.rotate(-degree*Math.PI/180, x, 20);//旋转回去
x+=30;
}
}
