import javax.servlet 出错

本文介绍了解决Eclipse项目中出现的javax.servlet.http.HttpServletRequest无法解析的问题。通常原因是项目缺少servlet-api.jar文件,文中提供了详细的步骤指导如何通过配置Server Runtime来解决此问题。

Error:

The import javax.servlet cannot be resolved

The import javax.servlet.http.HttpServletRequest cannot be resolved

Description:

我们经常会把别人的项目copy到自己这里进行二次开发或者参考,有的时候会发生上面的错误,

即eclipse项目里我们导入的项目里提示HttpServletRequest 不能引用,会伴随头疼的小红叉出现。如下图:

The imp<wbr>ort javax.servlet.http.HttpServletRequest cannot be resolved - 萧飒 - 萧飒的博客

Accuse:

具体原因是我们工程里面web-inf/lib目录下少了相应的包:Package javax.servlet.http引起的;

通俗且确切的讲就是缺少TOMCAT_HOME\lib下的servlet-api.jar

我导入别人的项目,在别人的机器上他配置了Server,一般都是tomcat,而在拷贝的过程中Server的那些library是不会随项目一起拷贝过来的,除非别人把tomcat的library已经拷贝到WEB-INF\lib下了。

Action:

Project -> Properties -> Java Build Path -> Add Library -> Server Runtime -> next -> 选择你的Server -> Finish

The imp<wbr>ort javax.servlet.http.HttpServletRequest cannot be resolved - 萧飒 - 萧飒的博客

package com.cissst.servlet; import java.io.IOException; import javax.servlet.RequestDispatcher; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import com.cissst.entity.Admin; import com.cissst.entity.CustomAccount; import com.cissst.service.IAdminService; import com.cissst.service.ICustomAccountService; import com.cissst.service.impl.AdminServiceImpl; import com.cissst.service.impl.CustomAccountServiceImpl; import com.cissst.util.MD5Util; import com.mysql.cj.AbstractQuery; public class UserServlet extends HttpServlet { @Override protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); response.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset=UTF-8"); String action = request.getParameter("action"); IAdminService as = new AdminServiceImpl(); ICustomAccountService cs = new CustomAccountServiceImpl(); HttpSession session = request.getSession(); switch (action) { case "login": handleLogin(request, response, session, as, cs); break; case "logout": case "relogin": handleLogout(session, response); break; } } private void handleLogin(HttpServletRequest request, HttpServletResponse response, HttpSession session, IAdminService adminService, ICustomAccountService accountService) throws IOException { String username = request.getParameter("username"); String password = MD5Util.encode(request.getParameter("password")); String userType = request.getParameter("usertype"); // 根据用户类型验证登录 if ("admin".equals(userType)) { Admin admin = adminService.findBynp(username, password); if (admin != null) { session.setAttribute("admin", admin); response.sendRedirect("index.jsp"); return; } } else if ("user".equals(userType)) { CustomAccount account = accountService.findBynp(username, password); if (account != null) { session.setAttribute("custom_Account", account); response.sendRedirect("index2.jsp"); return; } } // 统一处理登录失败 handleLoginFailure(request, response); } private void handleLogout(HttpSession session, HttpServletResponse response) throws IOException { if (session != null) { session.invalidate(); } response.sendRedirect("login.jsp"); } private void handleLoginFailure(HttpServletRequest request, HttpServletResponse response) throws IOException { // 使用传入的 request 对象 HttpSession session = request.getSession(); session.setAttribute("loginError", "用户名或密码错误"); response.sendRedirect("login.jsp"); } } at com.cissst.servlet.UserServlet.service(UserServlet.java:36)
最新发布
08-04
这是demo.java文件内容:import jakarta.servlet.ServletException; import jakarta.servlet.http.HttpServlet; import jakarta.servlet.http.HttpServletRequest; import jakarta.servlet.http.HttpServletResponse; import javax.servlet.annotation.WebServlet; import java.io.IOException; @WebServlet("/demo") public class demo extends HttpServlet { @Override protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.print("你好"); response.getWriter().write("你好"); } }web.xml的内容:<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0"> </web-app>这是pom.xml的文件内容:<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>org.example</groupId> <artifactId>javaweb</artifactId> <version>1.0-SNAPSHOT</version> <packaging>war</packaging> <properties> <maven.compiler.source>22</maven.compiler.source> <maven.compiler.target>22</maven.compiler.target> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <!--Servlet依赖坐标--> <dependencies> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>3.1.0</version> <scope>provided</scope> </dependency> </dependencies> </project>你看看是不是 配置出错导致的404?
05-10
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