Respons_案例_输出字节数据和验证码分析实现

Respons_案例_输出字节数据

服务器输出字节数据到浏览器

　　步骤：

　　　　获取字节输出流

　　　　输出数据

resp.setCharacterEncoding("text/html;charset=utf-8");

        ServletOutputStream outputStream = resp.getOutputStream();
        outputStream.write("你好".getBytes("utf-8"));

验证码分析

创建一对象，在内存中图（验证码对象）

美化图片

将图片输出到页面

@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        int width = 100;
        int height = 50;
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        Graphics graphics = image.getGraphics();
        graphics.setColor(Color.PINK);
        graphics.fillRect(0,0,width,height);

        graphics.setColor(Color.BLUE);
        graphics.drawRect(0,0,width-1,height-1);


        String str = "ABCDEFGHIGKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

        Random random = new Random();
        for (int i = 1; i <=4; i++) {
            int i1 = random.nextInt(str.length());
            char c = str.charAt(i1);
            graphics.drawString(c+"",width/5*i,height/2);
        }

//        graphics.drawString("A",20,25);
//        graphics.drawString("B",40,25);
//        graphics.drawString("C",60,25);
//        graphics.drawString("D",80,25);


        graphics.setColor(Color.green);

        for (int i = 0; i <10; i++) {
            int x1 = random.nextInt(width);
            int x2 = random.nextInt(width);

            int y1 = random.nextInt(height);
            int y2 = random.nextInt(height);
            graphics.drawLine(x1,y1,x2,y2);
        }

        ImageIO.write(image,"jpg",resp.getOutputStream());
    }

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        window.onload = function () {
           var img =  document.getElementById("checkCode");
           img.onclick = function () {

               var date = new Date().getTime();

                img.src = "/checkCodeServlet?"+date;
           }
        }
    </script>
</head>
<body>
    <img id="checkCode" src="/checkCodeServlet"/>
    <a id="change" href="">看不清换一张</a>
</body>
</html>

posted on 2022-08-10 10:23 淤泥不染阅读(27) 评论(0) 编辑收藏举报

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