如何解决“ java.lang.IllegalStateException：BeanResult'customer'的BindingResult或普通目标对象都不能用作请求属性”？
问题内容：
我正在尝试将Spring Validation与批注一起使用，并且不断遇到相同的异常：
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'customer' available as request attribute
at org.springframework.web.servlet.support.BindStatus.<init>(BindStatus.java:141)
at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getBindStatus(AbstractDataBoundFormElementTag.java:178)
at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getPropertyPath(AbstractDataBoundFormElementTag.java:198)
at org.springframework.web.servlet.tags.form.LabelTag.autogenerateFor(LabelTag.java:129)
at org.springframework.web.servlet.tags.form.LabelTag.resolveFor(LabelTag.java:119)
Truncated. see log file for complete stacktrace
我看了几本教程，并仔细检查了我能想到的所有内容。我不确定我的问题在哪里。网页加载时都会发生该异常。任何帮助，将不胜感激。
弹簧-mvc-servlet.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context"
xmlns:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
<context:component-scan base-package="controllers"/>
<mvc:annotation-driven/>
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property value="/" name="prefix"></property>
</bean>
</beans>
addCustomer.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ taglib uri="http://www.springframework.org/tags/form" prefix="form"%>
<!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>Add Customer</title>
</head>
<body>
<form:form action="addCustForm" method="POST" commandName="customer" modelAttribute="customer">
<table border="2">
<tr><td><form:label path="fname">Customer First Name: </form:label></td><td><form:input path="fname" id="fname"/><form:errors path="fname" cssClass="error"/> </td></tr>
<tr><td><form:label path="lname">Customer Last Name: </form:label></td><td><form:input path="lname" id="lname"/><form:errors path="lname" cssClass="error"/> </td></tr>
<tr><td><form:label path="phone">Customer Phone Number: </form:label></td><td><form:input path="phone" id="phone"/><form:errors path="phone" cssClass="error"/> </td></tr>
<tr><td><form:label path="address">Customer Address: </form:label></td><td><form:input path="address" id="address"/><form:errors path="address" cssClass="error"/> </td></tr>
<tr><td><form:label path="email">Customer E-Mail: </form:label></td><td><form:input path="email" id="email"/><form:errors path="email" cssClass="error"/> </td></tr>
</table>
<input type="submit" value="Submit Customer Info"/>
</form:form>
</body>
</html>
AddCustomerController.java
package controllers;
import javax.servlet.http.HttpServletRequest;
import javax.validation.Valid;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import dao.Customer;
@Controller
@RequestMapping("/addCustForm")
public class AddCustomerController {
@RequestMapping(method=RequestMethod.POST)
public String addCustomer(@Valid Customer customer, BindingResult result, ModelMap map, HttpServletRequest request) throws Exception{
if(result.hasErrors()){
return "addCustomer.jsp";
}
map.addAttribute("message",customer.getFname());
return "Menu.jsp";
}
}
客户.java
package dao;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Pattern;
import javax.validation.constraints.Size;
import javax.xml.ws.BindingType;
import org.hibernate.validator.constraints.Email;
import org.hibernate.validator.constraints.NotEmpty;
import org.springframework.stereotype.Component;
@Component
@Entity
public class Customer {
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
int custid;
@Column
@NotEmpty/*(message="First Name Is Required")*/
/*@Pattern(regexp="{a-zA-Z}", message="First Name must be all letters")*/
String fname;
@NotEmpty/*(message="Last Name Is Required")*/
/*@Pattern(regexp="{a-zA-Z}", message="Last Name must be all letters")*/
String lname;
@NotEmpty/*(message="Address Is Required")*/
/*@Pattern(regexp="{a-zA-Z0-9}", message="Address must be contain only letters and numbers")*/
String address;
@NotEmpty/*(message="Email is Required")*/
/*@Email(message="Invalid Email Address")*/
String email;
@NotEmpty/*(message="Phone Number is Required")*/
/*@Size(min=10,max=10)
@Pattern(regexp="{0-9}", message="Phone Number must be all Numbers(no '- or ()'")*/
String phone;
//Getters and Setters
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:web="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<display-name>Inventory-Management-System</display-name>
<welcome-file-list>
<welcome-file>Menu.jsp</welcome-file>
</welcome-file-list>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring-mvc-servlet.xml</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<servlet>
<servlet-name >spring-mvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>spring-mvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
问题答案：
从您的评论看来，您似乎正在将初始请求发送到
localhost:7001/InventoryManagementProject/addCustomer.jsp
我将假设这意味着所讨论的JSP是生成的WAR的根源。因此，您无需通过Spring即可直接访问它@Controller。 但是，这就是问题所在。
您的JSP包含
<form:form action="addCustForm" method="POST" commandName="customer" modelAttribute="customer">
<form:form>是Spring
form标记库中的标记。处理完该请求后，它将查找名为commandName或在中指定的名称的请求属性modelAttribute（请注意，指定两者都是多余的，请仅使用其中之一）。在这种情况下，它将查找名为的请求属性customer，但是由于您尚未设置此类请求属性，因此处理此标记将失败。
一种解决方案是让您的请求@Controller在呈现JSP之前经过处理程序方法。首先，将你的JSP内WEB- INF并解决您InternalResourceViewResolver有一个适当的prefix和suffix。然后添加一个像
@RequestMapping(value = "/add-customer", method = RequestMethod.GET)
public String getAddCustomerForm(Model model) {
model.addAttribute("customer", new Customer());
return "addCustomer";
}
这样做是Customer在模型属性中添加一个新对象（最终被添加为请求属性），以便在创建表单时将其用作模板。
