提交响应后无法转发

提交响应后无法转发

这段报错代码是为什么?

以下为报错内容和login相关代码

问题描述：

严重: 在路径为[/library]的上下文中，servlet[com.imooc.servlet.LoginServlet]的Servlet.service()引发异常

java.lang.IllegalStateException: 提交响应后无法转发

at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:325)

at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:315)

at com.imooc.servlet.LoginServlet.doGet(LoginServlet.java:55)

at com.imooc.servlet.LoginServlet.doPost(LoginServlet.java:62)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:652)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)

at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)

at com.imooc.fiter.AuthFilter.doFilter(AuthFilter.java:36)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)

at com.imooc.fiter.EncodeFilter.doFilter(EncodeFilter.java:30)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:201)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)

at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:544)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)

at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:698)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:364)

at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:616)

at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)

at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:831)

at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1629)

at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)

at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)

at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)

at java.lang.Thread.run(Thread.java:745)

相关代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<html>
<head>
<meta charset="UTF-8">
<title>登录</title>
<link rel="stylesheet" href="css/login.css">
<script type="text/javascript">
	function changeImg() {
		var codeImg = document.getElementById("codeImg");
		codeImg.src = "${pageContext.request.contextPath }/KaptchaServlet?time="
				+ new Date().getTime();
	}
</script>
</head>
<body>
	<div class="login">
		<div class="header">
			<h1>
				<a href="/login.do">登录</a>
				<p>${ msg }</p>
			</h1>
			<button></button>
		</div>
		<form action="${pageContext.request.contextPath }/login.do"
			method="post">
			<div class="name">
				<input type="text" id="name" name="username">
				<p></p>
			</div>
			<div class="pwd">
				<input type="password" id="pwd" name="password">
				<p></p>
			</div>
			<div class="code">
				<input type="text" id="code" name="verifyCode" style="width: 150px">
				&nbsp;&nbsp;&nbsp;&nbsp; <img id="codeImg" onclick="changeImg()"
					src="${pageContext.request.contextPath }/KaptchaServlet"
					style="width: 150px; height: 42px; vertical-align: middle;">
				<p></p>
			</div>
			<div class="btn-red">
				<input type="submit" value="登录" id="login-btn">
			</div>
		</form>
	</div>
</body>
</html>

相关代码：

相关代码：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://xmlns.jcp.org/xml/ns/javaee"
	xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
	id="WebApp_ID" version="3.1">
	<display-name>library</display-name>
	<welcome-file-list>
		<welcome-file>index.html</welcome-file>
		<welcome-file>index.htm</welcome-file>
		<welcome-file>index.jsp</welcome-file>
		<welcome-file>default.html</welcome-file>
		<welcome-file>default.htm</welcome-file>
		<welcome-file>default.jsp</welcome-file>
	</welcome-file-list>
	<!-- 配置Kaptcha验证码 -->
	<servlet>
		<servlet-name>KaptchaServlet</servlet-name>
		<servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class>
		<!-- 修改验证码长度 -->
		<init-param>
			<param-name>kaptcha.textproducer.char.length</param-name>
			<param-value>4</param-value>
		</init-param>
	</servlet>
	<servlet-mapping>
		<servlet-name>KaptchaServlet</servlet-name>
		<url-pattern>/KaptchaServlet</url-pattern>
	</servlet-mapping>
	<!-- 配置登录过滤器，/*代表拦截所有请求 -->
	<filter>
		<filter-name>EncodeFilter</filter-name>
		<filter-class>com.imooc.fiter.EncodeFilter</filter-class>
		<init-param>
			<param-name>encoding</param-name>
			<param-value>UTF-8</param-value>
		</init-param>
	</filter>
	<filter>
		<filter-name>AuthFilter</filter-name>
		<filter-class>com.imooc.fiter.AuthFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>EncodeFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
	<filter-mapping>
		<filter-name>AuthFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>

</web-app>


package com.imooc.servlet;

import java.io.IOException;
import java.util.List;

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 com.imooc.domain.User;
import com.imooc.servers.UserService;
import com.imooc.servers.impl.UserServiceImpl;

/**
 * Servlet implementation class LoginServlet
 */
@WebServlet("/login.do")
public class LoginServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		// 获得session中保存的验证码的信息
		String code1 = (String) request.getSession()
				.getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
		// 接受数据
		String username = request.getParameter("username");
		String password = request.getParameter("password");
		// 封装数据
		User user = new User(username, password);
		// 处理数据：完成登录
		UserService userService = new UserServiceImpl();
		// 获得用户列表的集合
		List<User> userList = (List<User>) getServletContext().getAttribute("userList");
		User existUser = userService.login(userList, user);
		// jsp显示结果
		// 调用了login方法下面就是要判断了
		if (existUser == null) {
			// 登录失败
			request.setAttribute("msg", "用户名或密码错误！");
			request.getRequestDispatcher("/login.jsp").forward(request, response);
		} else {
			// 登录成功
			// 将用户信息保存
			request.getSession().setAttribute("existUser", existUser);
			response.sendRedirect(request.getContextPath() + "/categoryList.jsp");
		}
		// 完成验证码的校验：
		// 接收前台表单提交的验证码的信息
		String code2 = request.getParameter("verifyCode");
		if (code2 == null || !code2.equalsIgnoreCase(code1)) {
			request.setAttribute("msg", "验证码输入不正确!");
			request.getRequestDispatcher("/login.jsp").forward(request, response);
			return;
		}
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

}

相关代码：

相关代码：

package com.imooc.fiter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.imooc.domain.User;

public class AuthFilter implements Filter {
	public AuthFilter() {
	}

	public void destroy() {
	}

	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		// 记得这里要强转一下request为它的子类HttpServletrequest，response同理
		HttpServletRequest req = (HttpServletRequest) request;
		HttpServletResponse res = (HttpServletResponse) response;

		// 获取唯一资源地址
		String uri = req.getRequestURI().toString();
		// 对后缀进行放行
		// 当查找到符合条件的字段时放行，然后返回
		if (uri.indexOf(".css") != -1 || uri.indexOf(".jpg") != -1 || uri.indexOf(".png") != -1
				|| uri.indexOf("login") != -1 || uri.indexOf(".js") != -1 || uri.indexOf("eckImg") != -1
				|| uri.indexOf("Servlet") != -1) {
			chain.doFilter(request, response);
			return;
		}

		// 对Session中是否有用户进行过滤
		// 先从Session域中获取一下
		User user = (User) req.getSession().getAttribute("existUser");
		// 判断一下是否为空，空字符串是否等于existUser，如果为空则说明还未登录，并转发回登录页面
		if (user == null || "".equals(user)) {
			// 未登录
			req.getSession().setAttribute("msg", "用户未登录");
			res.sendRedirect(req.getContextPath() + "/login.jsp");
			return;
		} else {
			// 登录了就放行
			chain.doFilter(request, response);
			return;
		}

	}

	public void init(FilterConfig fConfig) throws ServletException {
	}

}


​package com.imooc.fiter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class EncodeFilter implements Filter {
	private String encoding;
	@Override
	public void destroy() {
		// TODO Auto-generated method stub

	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		HttpServletRequest req=(HttpServletRequest)request;
		HttpServletResponse rep=(HttpServletResponse)response;
		req.setCharacterEncoding(encoding);
		rep.setCharacterEncoding(encoding);
		rep.setContentType("text/html;charset="+encoding);
		chain.doFilter(request,response);
	}

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		encoding=filterConfig.getInitParameter("encoding");
	}

}
LesslieZhang 2021-05-11
源自：项目：登录注册功能   6-2 项目作业
13
收起

正在回答

登陆购买课程后可参与讨论，去登陆吧

1回答
好帮手慕小班 回答被采纳获得+3积分 2021-05-12 11:26:27

同学你好，根据报错信息，提交响应后无法转发，一般出现重复的重定向或者转发，就会出现这个异常。检查贴出代码，同学在第一次判断完成，并执行跳转后，并没有书写return等跳出语句，此时会继续向下执行，就会出现提交响应后无法转发的情况，建议添加return语句再来试试，比如

​http://img1.sycdn.imooc.com//climg/609b4adc09d3445708190332.jpg

祝学习愉快！

0
收起回答
问题已解决，确定采纳
还有疑问，暂不采纳

恭喜解决一个难题，获得1积分~

来为老师/同学的回答评分吧

0 星

相似问题

请求转发与响应重定向的应用场景？
27 0 3
提交响应后无法转发
16 0 1
事务控制执行结束后，不手动开启自动提交，后续就再也没法自动提交了吗
1 0 3
在提交响应后无法调用sendRedirect（）
70 0 1
在对服务器响应进行后处理
15 0 3

登录后可查看更多问答，登录/注册

2. 从网页搭建入门JavaWeb
  • 参与学习           人
  • 提交作业       676    份
  • 解答问题       9666    个

本阶段将从前端网页搭建入手，到Java Web基础，前后端结合助你完成Java Web小白的蜕变！

了解课程

本课精华内容

问答 作业

4-3个人程序源码，提供给各位参考！

63 1

2-4 编程练习

22 1

text-align和direction有什么区别

13 1

交作业交作业交作业

225 2

是不是只有在JS语言中局部变量的定义才可以放在else语句中

24 1

查看更多本课问答
请稍等 ...
微信客服

购课补贴
联系客服咨询优惠详情

 帮助反馈 APP下载

慕课网APP
您的移动学习伙伴

 公众号

扫描二维码
关注慕课网微信公众号

在线咨询

领取优惠

免费试听

领取大纲

扫描二维码，添加
你的专属老师