response-实现验证码

public static final int WIDTH =120;
public static final int HEIGHT= 25;
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
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
setBackGround(g);
//2.设置边框
setBorder(g);
//3.画干扰线
drawRandomLine(g);
//4.写随机数
drawRandomNum((Graphics2D)g);
//5.写给浏览器
response.setContentType("image/jpeg");
//发头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 drawRandomNum(Graphics2D g) {
g.setColor(Color.RED);
g.setFont(new Font("宋体",Font.BOLD,20));
String base = "\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a";
//{\u4e00-\u9fa5}
int x=5;
for (int i = 0; i < 4; i++) {

int degree = new Random().nextInt()%30;
String ch =base.charAt(new Random().nextInt(base.length()))+"";
g.rotate(degree*Math.PI/180,x,20);//设置旋转角度
g.drawString(ch, x, 20);
g.rotate(-degree*Math.PI/180,x,20);
x+=30;

}

}

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 setBorder(Graphics g) {

g.setColor(Color.BLUE);
g.drawRect(1, 1, WIDTH-2,HEIGHT-2);
}

private void setBackGround(Graphics g) {

g.setColor(Color.WHITE);
g.fillRect(0, 0, WIDTH, HEIGHT);
}