页面调整

在jsp页面添加 （添加，删除，查询）

<div style="float: right;margin: 5px;">
    <a class="btn btn-primary" href="${pageContext.request.contextPath}/add.jsp">添加联系人</a>
    <a class="btn btn-primary" href="add.html">删除选择</a>
</div>

<form class="form-inline">
    <div class="form-group">
        <label for="exampleInputName2">姓名</label>
        <input type="text" class="form-control" id="exampleInputName2">
    </div>
    <div class="form-group">
        <label for="exampleInputName3">籍贯</label>
        <input type="text" class="form-control" id="exampleInputName3">
    </div>
    <div class="form-group">
        <label for="exampleInputEmail2">邮箱</label>
        <input type="email" class="form-control" id="exampleInputEmail2">
    </div>
    <button type="submit" class="btn btn-default">查询</button>
</form>

运行结果：

 登录功能_验证码显示

　　登录：调整页面，添加验证码

　写入验证码

  @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        int width = 100;
        int height = 50;

        //1.创建一对象 在内存中图片（验证码图片对象）
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        //2.美化图片
        //2.1填充背景色
        Graphics g = image.getGraphics();//画笔对象
        g.setColor(Color.PINK);
        g.fillRect(0,0,width,height);

        //2.2画边框
        g.setColor(Color.BLUE);
        g.drawRect(0,0,width-1 ,height-1);

        String str="ABCDEFGHIJLMNOPQRTUVWXYZabcdefghigklmnopqstuvwxyz0123456789";

        //生成随机角标
        Random ran = new Random();
        StringBuilder sb = new StringBuilder();
        for (int i=1;i<=4;i++){
            int index=ran.nextInt(str.length());
            //获取字符
            char ch = str.charAt(index);//随机字符
            sb.append(ch);
            //2.3写验证码
            g.drawString(ch+"",width/5*i,height/2);
        }
        String checkCode_session = sb.toString();
        //将验证码存入session
        req.getSession().setAttribute("checkCode_session",checkCode_session);

        //2.4画干扰线
        g.setColor(Color.GREEN);
        //随机生成坐标点
        for (int i = 0; i < 10; i++) {
            int x1=ran.nextInt(width);
            int x2=ran.nextInt(width);

            int y1=ran.nextInt(height);
            int y2=ran.nextInt(height);
            g.drawLine(x1,x2,y1,y2);
        }

        //3.将图片输出到页面展示
        ImageIO.write(image,"jpg",resp.getOutputStream());



    }

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

在jsp页面修饰，

<a href="javascript:refreshCode()">
    <img src="${pageContext.request.contextPath}/CheckCodeServlet" title="看不清点击刷新" id="vcode"/>
</a>

添加点击换验证码，加入时间

<script>
    function refreshCode() {
    //    获取验证码图片对象
        var vco = document.getElementById("vcode");
    //    设置其src属性，加时间搓
        vco.src="${pageContext.request.contextPath}/CheckCodeServlet?time"+new Date().getTime();
    }
</script>

点击换验证码