spring-mvc - Spring 与 <form :form commandName ="xy" 的注释关系

标签 spring-mvc

这个问题在这里已经有了答案:





What causes "java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'command' available as request attribute"?

(6 个回答)


5年前关闭。




我是 Spring 注释和 MVC 的新手。我的第一页是 home.jsp，现在它没有出现在 Tomcat 服务器中，我在控制台中看到了最后显示的错误。
我试图创建一个非常简单的注释应用程序。这里是 Controller 。

import javax.validation.Valid;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.ui.ModelMap;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller

    //@RequestMapping()
    public class UserLoginController {

    public UserLoginController(){

    }
        //@RequestMapping(value="/get" , method = RequestMethod.GET)
    //@ModelAttribute("user")
        public String get(final ModelMap model) {

            User userForm = new User();
      model.addAttribute("userLogin", userForm);
       return "form";
        }

        @RequestMapping(value="/home.jsp", method = RequestMethod.POST)
        public String post(Model model) {

           String test=" inside here";

            return "success";
        }
    }

这是 JSP
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@ page session="false" %>
<%@ include file="/WEB-INF/views/header.jsp" %>

 <html>
<head>
<meta http-equiv="Content-Type" content="text/html">
<title>iBank - Home-version 2.0</title>
</head>
<body>
<h1 align="center">Welcome to iBank-Dhiren</h1>
<h2 align="center">Your Online Bank Portal</h2>
<p align="center">   
Today is ${today}.<br/>
<a href="<%=request.getContextPath()%>/admin.htm">Modified Administration Site-version-1.0 </a>
</p>
</body>
</html>

<p>
    <form:form  method="post" commandName="user">
        <div>
            <form:label path="name">Name:</form:label>
            <form:input path="name"/>
            <form:errors path="name" />
        </div>
        <div>
            <form:label path="email">Email:</form:label>
            <form:input path="email" />
            <form:errors path="email" />
        </div>
        <div>
            <input type="submit" value="  OK  "/>
        </div>
    </form:form>
</p>

</html>

现在 JSP 应该如何提交到 UserLoginController。我看不到注释值之间的任何连接，而且我的 Tomcat 服务器也出现此错误。
SEVERE: Servlet.service() for servlet jsp threw exception
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'user' 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:174)

谢谢
迪伦

好的，我无法再进一步了。我尝试了所有，但仍然完全卡住了。

我的 JSP
主页.jsp
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@ page session="false" %>
<%@ include file="/WEB-INF/views/header.jsp" %>

 <html>
<head>
<meta http-equiv="Content-Type" content="text/html">
<title>iBank - Home-version 2.0</title>
</head>
<body>
<h1 align="center">Welcome to iBank-Dhiren</h1>
<h2 align="center">Your Online Bank Portal</h2>
<p align="center">   
Today is ${today}.<br/>
<a href="<%=request.getContextPath()%>/admin.htm">Modified Administration Site-version-1.0 </a>
</p>
</body>
</html>

<p>
    <form:form  method="post" action="/user.jsp" modelAttribute="user">

        <div>
            <form:label path="firstName">Name:</form:label>
            <form:input path="firstName"/>
            <form:errors path="firstName" />
        </div>
        <div>
            <form:label path="password">Password:</form:label>
            <form:input path="password" />
            <form:errors path="password" />
        </div>
        <div>
            <form:label path="middleName">Middle name:</form:label>
            <form:input path="middleName" />
            <form:errors path="middleName" />
        </div>
        <div>
            <form:label path="lastName">LastName:</form:label>
            <form:input path="lastName" />
            <form:errors path="lastName" />
        </div>


        <div>
            <input type="submit" value="  OK  "/>
        </div>
    </form:form>
</p>

</html>

我的用户登录 Controller 
import javax.validation.Valid;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.ui.ModelMap;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller

    //@RequestMapping()
    public class UserLoginController {

    public UserLoginController(){

    }
        //@RequestMapping(value="/get" , method = RequestMethod.GET)
    //@ModelAttribute("user")
        public String get(final ModelMap model) {

            User userForm = new User();
      model.addAttribute("userLogin", userForm);
       return "form";
        }

        @RequestMapping(value="/user.jsp", method = RequestMethod.POST)
        public String post(final User user, final BindingResult result, Model mv) {

           String test=" inside here";

            return "success";
        }
    }

用户类
import javax.validation.constraints.Size;

import org.hibernate.validator.constraints.NotEmpty;

public class User {
/*  @NotEmpty
    @Size(max = 20)
    */
private String userId;
    /*@NotEmpty
    @Size(max = 20)
*/
private String password;
private String firstName;
private String middleName;
private String lastName;
//private int userAccessLevel;
/**
 * @return the userId
 */
public String getUserId() {
    return userId;
}
/**
 * @param userId the userId to set
 */
public void setUserId(String userId) {
    this.userId = userId;
}
/**
 * @return the password
 */
public String getPassword() {
    return password;
}
/**
 * @param password the password to set
 */
public void setPassword(String password) {
    this.password = password;
}
/**
 * @return the firstName
 */
public String getFirstName() {
    return firstName;
}
/**
 * @param firstName the firstName to set
 */
public void setFirstName(String firstName) {
    this.firstName = firstName;
}
/**
 * @return the middleName
 */
public String getMiddleName() {
    return middleName;
}
/**
 * @param middleName the middleName to set
 */
public void setMiddleName(String middleName) {
    this.middleName = middleName;
}
/**
 * @return the lastName
 */
public String getLastName() {
    return lastName;
}
/**
 * @param lastName the lastName to set
 */
public void setLastName(String lastName) {
    this.lastName = lastName;
}
/**
 * @return the userAccessLevel
 *
public int getUserAccessLevel() {
    return userAccessLevel;
}
*/
/**
 * @param userAccessLevel the userAccessLevel to set
 *
public void setUserAccessLevel(int userAccessLevel) {
    this.userAccessLevel = userAccessLevel;
}*/

}

这些是 context.xml 文件
servlet-context.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:beans="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-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">

    <!-- DispatcherServlet Context: defines this servlet's request-processing infrastructure -->

    <!-- Enables the Spring MVC @Controller programming model -->
    <annotation-driven />

    <!-- Handles HTTP GET requests for /resources/** by efficiently serving up static resources in the ${webappRoot}/resources directory -->
    <resources mapping="/resources/**" location="/resources/" />

    <!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory -->
    <beans:bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <beans:property name="prefix" value="/WEB-INF/views/" />
        <beans:property name="suffix" value=".jsp" />
    </beans:bean>

        <!-- Imports user-defined @Controller beans that process client requests -->

    <context:component-scan base-package="mytest.apps" />

</beans:beans>

有人能告诉我为什么 home.jsp 没有出现吗

web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <display-name>appServlet</display-name>
    <!-- The definition of the Root Spring Container shared by all Servlets and Filters -->
    <context-param>  
  <param-name>log4jConfigLocation</param-name>  
  <param-value>/WEB-INF/log4j.xml</param-value>  
</context-param>  
<listener>  
  <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>  
</listener> 

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/spring/appServlet/root-context.xml</param-value>
    </context-param>

    <!-- Creates the Spring Container shared by all Servlets and Filters -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <!-- Processes application requests -->
    <servlet>
        <servlet-name>appServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring/appServlet/servlet-context.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>appServlet</servlet-name>
        <url-pattern>/</url-pattern>

    </servlet-mapping>
</web-app>

由于所有这些错误，当我尝试访问 Web 应用程序的第一页时，我在 Tomcat 中遇到了这个错误。
INFO: At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned where no TLDs were found. Skipping JAR scanning can improve startup time and JSP compilation time.
log4j:ERROR Attempted to append to closed appender named [console].
Sep 14, 2011 10:02:39 PM org.apache.catalina.core.ApplicationDispatcher invoke
SEVERE: Servlet.service() for servlet jsp threw exception
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'user' 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:174)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getPropertyPath(AbstractDataBoundFormElementTag.java:194)
    at org.springframework.web.servlet.tags.form.LabelTag.autogenerateFor(LabelTag.java:129)
    at org.springframework.web.servlet.tags.form.LabelTag.resolveFor(LabelTag.java:119)
    at org.springframework.web.servlet.tags.form.LabelTag.writeTagContent(LabelTag.java:89)
    at org.springframework.web.servlet.tags.form.AbstractFormTag.doStartTagInternal(AbstractFormTag.java:102)
.
.
Sep 14, 2011 10:02:39 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [appServlet] in context with path [/AdministrativeApplication] threw exception [An exception occurred processing JSP page /WEB-INF/views/home.jsp at line 25

22:     <form:form  method="post" action="/user.jsp" modelAttribute="user">
23:      
24:         <div>
25:             <form:label path="firstName">Name:</form:label>
26:             <form:input path="firstName"/>
27:             <form:errors path="firstName" />
28:         </div>


Stacktrace:] with root cause
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'user' available as request attribute
    at org.springframework.web.servlet.support.BindStatus.<init>(BindStatus.java:141)

请帮忙

谢谢
迪伦

最佳答案 

class User() {
    String name;
    String email;

    //bean getters and setters
}

public String post(Model model, User user) {
   ....
}

几天前我才开始使用 Spring 绑定(bind)。

您设置它的方式我相信您的表单将尝试创建一个具有“电子邮件”和“名称”属性的“用户”对象。

编辑

我想我明白这个问题...
<form:form  method="post" commandName="user">

这告诉 spring 您想使用来自用户对象的数据预填充表单。如果这是您想要做的，那么您需要为 jsp 提供一个名为“user”的请求属性。

如果您尝试使用表单提交数据，我相信是这种情况，我认为您想改用它
<form:form  method="post" modelAttribute="user">

关于spring-mvc - Spring 与 <form :form commandName ="xy" 的注释关系，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/7356684/

上一篇：svn - 如何在没有服务器的情况下使用 SVN？

下一篇：ruby-on-rails - 如何在 Rails 中使数据库字段只读？

相关文章：

java - @ModelAttribute在Spring框架中如何工作？

java - Spring使用匿名身份验证提供程序来使用 guest 用户

spring - 在 Spring 中结合 GET 和 POST 请求方法

mysql - Spring多事务回滚

spring-mvc - POST 请求的 Spring 安全配置

java - 动态包含在 JSP 模板中

spring-boot - Spring Boot gzip 压缩 - 响应大小没有减少

java - 如何获取 url 中传递的值到模型和 View Controller ？

java - 在 404 和 500 Http 错误 Spring MVC 上发送电子邮件或记录错误

javascript - 预期的十六进制数字

©2024 IT工具网  联系我们