1.首先导入jar包
2.servlet代码
代码语言：javascript复制package com.itqf.controller;
import cn.dsna.util.images.ValidateCode;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* zt
* 2020/9/14
* 22:15
*/
@WebServlet(value = "/img")
public class ImageServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ValidateCode validateCode = new ValidateCode(100, 30, 4, 30);
String code = validateCode.getCode();
validateCode.write(response.getOutputStream());
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
}3.jsp代码
代码语言：javascript复制<%--
Created by IntelliJ IDEA.
User: 49841
Date: 2020/9/14
Time: 22:14
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>index</title>
</head>
<body>
<h2>欢迎登录</h2>
<h2>呱？！，当前登录用户</h2>
<img src="${pageContext.request.contextPath}/img">
</body>
</html>4.或者将那个输出验证码的代码换成另一个
就是
代码语言：javascript复制validateCode.write(response.getOutputStream());换成
代码语言：javascript复制ImageIO.write(validateCode.getBuffImg(), "jpg", response.getOutputStream());//其实底层代码都是一样的：validateCode.write(response.getOutputStream());的底层代码就是
public void write(OutputStream sos) throws IOException {
ImageIO.write(this.buffImg, "png", sos);
sos.close();
}结果：
