Javaweb编写代码完成登陆验证，在验证输入与给出验证码一致的第一个if条件报错，该怎么改
package chapter3.servlet;
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;
@WebServlet(name = "LongingRedirectServlet",urlPatterns = "/LongingRedirectServlet")
public class LongingRedirectServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setCharacterEncoding("utf-8");
request.setCharacterEncoding("utf-8");
String un=request.getParameter("username");
String pw=request.getParameter("password");
String verifycode=request.getParameter("verifycode");
String yzm=(String)request.getSession().getAttribute("yzm");
String a ="你好";
if (verifycode.equals(yzm)) { //**就是这里第一个条件怎么表述成输入输出一致？**
if ("admin".equals(un)&&"123".equals(pw)) {
getServletContext().setAttribute("username", un);
response.sendRedirect(request.getContextPath() + "/index.jsp");
} else {
response.sendRedirect(request.getContextPath()+"/chapter3/jsp/login_imagecode.jsp");
}
}else {
a= "验证码错误请返重新输入";
}
if("admin".equals(un)&&"123".equals(pw)) {
if (verifycode.equals(yzm)) {
getServletContext().setAttribute("username", un);
getServletContext().setAttribute("verifycode", verifycode);
response.sendRedirect(request.getContextPath() + "/index.jsp");
}
}
else {
response.sendRedirect(request.getContextPath()+"/chapter3/jsp/login_imagecode.jsp");
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
还有这个index.jps需要怎么改
<%--
Created by IntelliJ IDEA.
User: Lenovo
Date: 2022/2/22
Time: 16:49
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>javaweb课程教学例程</title>
</head>
<body>
<%
String username=(String)application.getAttribute("username");
String verifycode=(String)application.getAttribute("verifycode");
if (username==null)
username="";
%>
<%=username%> 欢迎进入javaweb的世界!!
</body>
</html>
这是编写的login-imagecode.JSP
<%--
Created by IntelliJ IDEA.
User: 39519
Date: 2022/3/1
Time: 8:18
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>登录</title>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
<script type="text/javascript">
// 切换验证码
function refreshCode() {
// 获取验证码图片对象
var vcode = document.getElementById("vcode");
// 设置src属性，加上时间戳
vcode.src="${pageContext.request.contextPath}/imageCode?time=" + new Date().getTime();
}
</script>
</head>
<body>
<div class="container" style="width: 400px;">
<h3 style="text-align: center;">验证码登录演示</h3>
<form action="${pageContext.request.contextPath}/LongingRedirectServlet" method="post">
<div class="form-group">
<label for="user">用户名：</label>
<input type="text" name="username" class="form-control" id="user" placeholder="请输入用户名"/>
</div>
<div class="form-group">
<label for="password">密码：</label>
<input type="password" name="password" class="form-control" id="password" placeholder="请输入密码"/>
</div>
<div class="form-inline">
<label for="vcode">验证码：</label>
<input type="text" name="verifycode" class="form-control" id="verifycode" placeholder="请输入验证码" style="width: 120px;"/>
<a href="javascript:refreshCode()">
<img src="${pageContext.request.contextPath}/imageCode" title="看不清点击刷新" id="vcode"/>
</a>
</div>
<hr/>
<div class="form-group" style="text-align: center;">
<input class="btn btn btn-primary" type="submit" value="登录">
</div>
</form>
</div>
</body>
</html>
这是编写的验证码生成代码
package chapter01;
import javax.imageio.ImageIO;
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.awt.*;
import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Random;
@WebServlet(name = "CheckImageServlet",urlPatterns = "/imageCode")
public class CheckImageServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private List<String> words = new ArrayList<String>();// 集合中保存所有成语
@Override
public void init() throws ServletException {
//读取文本文件中的成语存于集合类，并遍历输出，在控制台查看正确与否
InputStream in = getServletContext().getResourceAsStream("/WEB-INF/words.txt");
try {
BufferedReader bf = new BufferedReader(new InputStreamReader(in, "UTF-8"));
String line;
while ((line = bf.readLine()) != null) {
words.add(line);//读取每一行的成语，并存于集合类words中
}
bf.close();
Iterator<String> iter = words.iterator();
while (iter.hasNext()) {
String s = (String) iter.next();
}
} catch (IOException e) {
e.printStackTrace();
}
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// 如下三句是控制浏览器禁止缓存当前文档内容
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");
response.setDateHeader("Expires", -1);
int width = 180;
int height = 30;
// 步骤一 绘制一张内存中图片
BufferedImage bufferedImage = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 步骤二 图片绘制背景颜色 ---通过绘图对象
Graphics graphics = bufferedImage.getGraphics();// 得到画图对象 --- 画笔
// 绘制任何图形之前 随机指定一个颜色
graphics.setColor(getRandColor(200, 250));//在117行定义，随机取得颜色
graphics.fillRect(0, 0, width, height);
// 步骤三 绘制边框
graphics.setColor(Color.WHITE);
graphics.drawRect(0, 0, width - 1, height - 1);
// 步骤四 四个随机数字,用到旋转等方法所以转换为Graphics2D
Graphics2D graphics2d = (Graphics2D) graphics;
// 设置输出字体
graphics2d.setFont(new Font("宋体", Font.BOLD, 18));
Random random = new Random();// 生成随机数
int index = random.nextInt(words.size());//在0和数组最大长度的范围内随机取一个下标
String word = words.get(index-1);// 获得该下标对应的成语
System.out.println(word);
//对四字成语中的每个字设定颜色，旋转的角度
// 定义x坐标
int x = 10;
for (int i = 0; i < word.length(); i++) {
// 随机颜色
graphics2d.setColor(new Color(20 + random.nextInt(110), 20 + random
.nextInt(110), 20 + random.nextInt(110)));
// 旋转 -30 --- 30度
int jiaodu = random.nextInt(60) - 30;
// 换算弧度
double theta = jiaodu * Math.PI / 180;
// 获得字母数字
char c = word.charAt(i);
// 将c 输出到图片
graphics2d.rotate(theta, x, 20);
graphics2d.drawString(String.valueOf(c), x, 20);
graphics2d.rotate(-theta, x, 20);
x += 40;
}
// 步骤五 绘制干扰线
graphics.setColor(getRandColor(160, 200));
int x1,x2,y1,y2;
for (int i = 0; i < 30; i++) {
x1 = random.nextInt(width);
x2 = random.nextInt(12);
y1 = random.nextInt(height);
y2 = random.nextInt(12);
graphics.drawLine(x1, y1, x1 + x2, x2 + y2);
}
// 将上面图片输出到浏览器 ImageIO
graphics.dispose();// 释放资源
ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
/**
* 取其某一范围的color
* @param fc int 范围参数1
* @param bc int 范围参数2
* @return Color
*/
private Color getRandColor(int fc, int bc) {
// 取其随机颜色
Random random = new Random();
if (fc > 255) {
fc = 255;
}
if (bc > 255) {
bc = 255;
}
int r = fc + random.nextInt(bc - fc);
int g = fc + random.nextInt(bc - fc);
int b = fc + random.nextInt(bc - fc);
return new Color(r, g, b);
}
}
