Java+JSP实现算数验证码
2019-12-30 本文已影响0人
念念碎平安夜
类似《纯Java+JSP验证码》
一、创建Servlet类验证结果
@WebServlet("/valiCode2")
public class ValiCode2 extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 1. 得到数据
String inCode = request.getParameter("inCode").toString().toLowerCase();
String valiCode = request.getSession().getAttribute("valiCode").toString().toLowerCase();
// 2. 验证是否正确
if (inCode.equals(valiCode)) {
response.sendRedirect("index.jsp");
} else {
request.getSession().setAttribute("err", "验证码输入错误，请重新输入！");
// 返回上一页
String url = request.getHeader("Referer");
response.sendRedirect(url);
}
}
}
二、生成算数画板
@WebServlet("/newCode2")
public class NewCode2 extends HttpServlet {
private Random random = new Random(); // 随机数对象
private int width = 140; // 宽度
private int height = 30; // 高度
private int fontsize = 18; // 字体大小
private String str = "+-*/";
private int value = -1; // 保存计算结果
private String randCode() {
int one = random.nextInt(100);
int two = random.nextInt(100) + 1;
char op = str.charAt(random.nextInt(str.length()));
switch (op) {
case '+':
value = one + two;
break;
case '-':
value = one - two;
break;
case '*':
value = one * two;
break;
case '/':
value = one / two;
break;
}
return "" + one + op + two + "=?";
}
// 返回随机颜色
private Color randColor() {
int r = random.nextInt(256);
int g = random.nextInt(256);
int b = random.nextInt(256);
return new Color(r, g, b);
}
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 1.创建画板
BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 2.创建画笔
Graphics2D pen = img.createGraphics();
// 3.生成随机内容
String code = randCode();
request.getSession().setAttribute("valiCode", value);
// 4.绘制内容
// 4.1设置绘制区域
pen.fillRect(0, 0, width, height);
// 4.2设置字体
pen.setFont(new Font("微软雅黑", Font.BOLD, fontsize + random.nextInt(5)));
// 4.3按顺序逐个绘制字符
for (int i = 0; i < code.length(); i++) {
pen.setColor(randColor());
// 绘制字符
pen.drawString(code.charAt(i) + "", 5 + i * fontsize, (fontsize + height) / 2 + random.nextInt(5));
}
// 4.4绘制噪音线
for (int i = 0; i < 2; i++) {
pen.setColor(randColor());
pen.setStroke(new BasicStroke(3));
pen.drawLine(random.nextInt(width / 2), random.nextInt(height), random.nextInt(width),
random.nextInt(height));
}
// 5.存为图片并发送
ServletOutputStream out = response.getOutputStream();
ImageIO.write(img, "png", out);
out.flush();
out.close();
}
}
三、用户登录页面
<style type="text/css">
.code_a {
color: #0000ff;
font-size: 12px;
text-decoration: none;
cursor: pointer;
}
#imgCode {
cursor: pointer;
}
</style>
<script type="text/javascript">
function changeCode() {
var imgCode = document.getElementById("imgCode");
imgCode.src = "newCode2?" + Math.random();
}
</script>
</head>
<body>
<form action="valiCode2" method="post">
<label>验证码:</label> <input type="text" id="inCode" name="inCode" /> <img
alt="" src="newCode2" align="center" id="imgCode"
onclick="changeCode()"> <a class="code_a"
onclick="changeCode()">换一张</a><br /> <input type="submit" value="登录" />
</form>
<div style="color: red;">${err}</div>
</body>
