尝试提交表单时出现以下错误：
"javax.servlet.ServletException: javax.servlet.jsp.JspException: No bean found under attribute key user"
这些是我的文件：
的pom.xml
<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>com.struts1</groupId>
<artifactId>struts1</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<build>
<sourceDirectory>src</sourceDirectory>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<plugin>
<artifactId>maven-war-plugin</artifactId>
<version>2.4</version>
<configuration>
<warSourceDirectory>WebContent</warSourceDirectory>
<failOnMissingWebXml>false</failOnMissingWebXml>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
</dependency>
<dependency>
<groupId>org.apache.struts</groupId>
<artifactId>struts-core</artifactId>
<version>1.3.10</version>
</dependency>
<dependency>
<groupId>org.apache.struts</groupId>
<artifactId>struts-taglib</artifactId>
<version>1.3.10</version>
</dependency>
</dependencies>
</project>
的web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>struts1</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>
<servlet>
<servlet-name>action</servlet-name>
<servlet-class>
org.apache.struts.action.ActionServlet
</servlet-class>
<init-param>
<param-name>config</param-name>
<param-value>
/WEB-INF/struts-config.xml
</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>action</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>
</web-app>
的struts-config.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.3//EN"
"http://struts.apache.org/dtds/struts-config_1_3.dtd">
<struts-config>
<form-beans>
<form-bean name="user" type="com.struts1.domain.User" />
</form-beans>
<action-mappings>
<action name="user" path="/userInteraction" scope="request" type="com.struts1.controller.UserInteraction" input="/index.jsp">
<forward name="success" path="/user.jsp" redirect="true" />
</action>
</action-mappings>
</struts-config>
的index.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@taglib uri="http://struts.apache.org/tags-bean" prefix="bean"%>
<%@taglib uri="http://struts.apache.org/tags-logic" prefix="logic"%>
<%@ taglib uri="http://struts.apache.org/tags-html" prefix="html"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Main Page</title>
</head>
<body>
<html:form action="/userInteraction.do">
<html:submit value="Send" />
</html:form>
</body>
user.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<%@taglib uri="http://struts.apache.org/tags-logic" prefix="logic"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<h1>Hello user!</h1>
<logic:equal name="user" property="firstName" value="evgheni" scope="request">
User Logged In
</logic:equal>
</body>
</html>
UserInteraction.java （操作类）
package com.struts1.controller;
import java.io.PrintWriter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import com.struts1.domain.User;
import com.struts1.persistance.UserDAOImpl;
import com.struts1.persistanceI.UserDAO;
public class UserInteraction extends Action{
@Override
public ActionForward execute(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response) throws Exception{
UserDAO userDAO = new UserDAOImpl();
request.setAttribute("user", userDAO.getUser(1));
return mapping.findForward("success");
}
}
User.java
package com.struts1.domain;
import org.apache.struts.action.ActionForm;
public class User extends ActionForm{
private String firstName;
private String lastName;
private int id;
public User(String firstName, String lastName, int id) {
this.firstName = firstName;
this.lastName = lastName;
this.id = id;
}
public User() {
super();
}
// getters and setter go here
}
userDAO.getUser(1)通过其ID从DB返回用户。 表单提交后会出现javax.servlet.ServletException错误。
我正在使用tomcat7容器和Java 8。
答案 0 :(得分：2)
如异常所示，在属性键“user”下找不到bean，因此我们感兴趣的区域是struts-config文件中的映射。我可以看到你在<action>和<form-bean>之间有一个正确的映射，但是当第一个请求被发送到Action类时，有一个转发将我们带到user.jsp但是有重定向到user.jsp，这意味着客户端将为user.jsp生成一个新请求，因此请求参数将在此过程中丢失。
有关转发与重定向的详细信息，请参阅此link。
只需删除转发映射中的重定向属性，您的代码就可以正常工作。