java.lang.IllegalStateException:Bean 名称“类别"的 BindingResult 和普通目标对象都不能用作请求属性

2022-01-13 00:00:00 annotations spring java Hibernate spring-form

我在网上查看了几乎所有与此问题相关的答案，但无法在我的代码中找出问题所在.

I looked almost all answers related this problem on the web but could not figure out the problem in my code.

这是我的 JSP 页面.

Here is my JSP page.

<form:form method="POST" commandName="category" modelAttribute="category" action="search_category">
    <form:input path="category_name" /> 
    <input type="submit" value="Submit">  
</form:form>

当我删除时

<form:input path="category_name" />

它工作正常.我可以与我的控制器通信.所以问题与这条线有关.

It works fine. I can communicate with my controller. So the problem is related to this line.

@Controller
public class SearchCategory {

    @Autowired      
    private CategoryService categoryService;

    @RequestMapping(value = "/search_category",  method = RequestMethod.POST)
    public @ResponseBody String searchCategoryFromDatabase(@ModelAttribute("category") Category category, BindingResult result){        

        return "something";
    }
}

这是我的 web.xml

Here is my 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">

    <!-- 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/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>

     <!-- The definition of the Root Spring Container shared by all Servlets and Filters -->  
    <context-param>  
        <param-name>contextConfigLocation</param-name>  
        <param-value>/WEB-INF/applicationContext.xml</param-value>  
    </context-param>  

    <filter>  
        <filter-name>hibernateFilter</filter-name>  
        <filter-class>org.springframework.orm.hibernate4.support.OpenSessionInViewFilter</filter-class>  
    </filter>  
    <filter-mapping>  
        <filter-name>hibernateFilter</filter-name>  
        <url-pattern>/*</url-pattern>  
    </filter-mapping>      

    <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

</web-app>

这是我的 servlet-context.xml

This is my servlet-context.xml 

<!--  Set the default page as index.jsp -->
<mvc:view-controller path="/" view-name="index"/>

<!-- Map resources --> 
<mvc:resources mapping="/resources/**" location="/, classpath:/META-INF/web-resources/" /> 

<!-- Map simple view name such as "test" into /WEB-INF/views/test.jsp -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/WEB-INF/" />
    <property name="suffix" value=".jsp" />
</bean>

还有我的 applicationContext.xml

And my applicationContext.xml

<!-- Enable @Controller annotation support -->
    <mvc:annotation-driven />

    <context:annotation-config/>    

    <!--  Set the default page as index.jsp -->
    <mvc:view-controller path="/" view-name="index"/>

     <!-- Map resources --> 
    <mvc:resources mapping="/resources/**" location="/, classpath:/META-INF/web-resources/" /> 

    <!-- Map simple view name such as "test" into /WEB-INF/views/test.jsp -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/" />
        <property name="suffix" value=".jsp" />
    </bean>

    <!-- Scan classpath for annotations (eg: @Service, @Repository etc) -->
    <context:component-scan base-package="com.XXXX"/>

    <!-- JDBC Data Source. It is assumed you have MySQL running on localhost port 3306 with 
         username root and blank password. Change below if it's not the case -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/XXXX"/>
        <property name="username" value="XXXX"/>
        <property name="password" value="XXXX"/>
        <property name="validationQuery" value="SELECT 1"/>
    </bean>

    <!-- Hibernate Session Factory -->
    <bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="configLocation">
            <value>classpath:hibernate.cfg.xml</value>
        </property>
        <property name="packagesToScan">
            <array>
                <value>com.XXXX</value>
            </array>
        </property>
        <property name="hibernateProperties">
            <value>
                hibernate.dialect=org.hibernate.dialect.MySQLDialect
            </value>
        </property>     
    </bean>

    <!-- Hibernate Transaction Manager -->
    <bean id="transactionManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactory"/>
    </bean>

    <!-- Activates annotation based transaction management -->
    <tx:annotation-driven transaction-manager="transactionManager"/>

我可能在我的 XML 文件中做错了什么.我是这个春天的新手——Hibernate 的工作人员，所以等待你的帮助.谢谢..

I am probably doing something wrong in my XML files. I am new for this Spring - Hibernate staff so waiting for your help. Thanks..

这是抛出的异常

Stacktrace:] with root cause
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'category' 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:168)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getPropertyPath(AbstractDataBoundFormElementTag.java:188)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getName(AbstractDataBoundFormElementTag.java:154)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.autogenerateId(AbstractDataBoundFormElementTag.java:141)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.resolveId(AbstractDataBoundFormElementTag.java:132)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.writeDefaultAttributes(AbstractDataBoundFormElementTag.java:116)
    at org.springframework.web.servlet.tags.form.AbstractHtmlElementTag.writeDefaultAttributes(AbstractHtmlElementTag.java:422)
    at org.springframework.web.servlet.tags.form.InputTag.writeTagContent(InputTag.java:142)
    at org.springframework.web.servlet.tags.form.AbstractFormTag.doStartTagInternal(AbstractFormTag.java:84)
    at org.springframework.web.servlet.tags.RequestContextAwareTag.doStartTag(RequestContextAwareTag.java:80)
    at org.apache.jsp.index_jsp._jspx_meth_form_005finput_005f0(index_jsp.java:208)
    at org.apache.jsp.index_jsp._jspx_meth_form_005fform_005f0(index_jsp.java:168)
    at org.apache.jsp.index_jsp._jspService(index_jsp.java:100)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.springframework.orm.hibernate4.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:149)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:722)

推荐答案

如果你通过 http://localhost:8080/yourapp 之类的方式访问 index.jspcode>，我假设你有一个 <welcome-file>.

If you're getting to index.jsp through something like http://localhost:8080/yourapp, I'll assume you have a <welcome-file> for it.

这意味着 index.jsp 无需 Spring 进行任何预处理即可生成 HTML.你正在尝试渲染这个

This means that the index.jsp generates the HTML without any pre-processing by Spring. You're trying to render this

<form:form method="POST" commandName="category" modelAttribute="category" action="search_category">
    <form:input path="category_name" /> 
    <input type="submit" value="Submit">  
</form:form>

其中 <form:form> 来自 Spring 的标签库.首先，请注意您同时使用了 commandName 和 modelAttribute.这是多余的.使用其中之一，而不是两者.其次，当您指定其中任何一个时，标记实现会查找具有指定名称的 HttpServletRequest 属性.在您的情况下，没有将此类属性添加到 HttpServletRequest 属性中.这是因为 Servlet 容器直接转发给你的 index.jsp.

where <form:form> is from Spring's tag library. First, note that you are using both commandName and modelAttribute. This is redundant. Use one or the other, not both. Second, when you specify either of these, the tag implementation looks for a HttpServletRequest attribute with the name specified. In your case, no such attribute was added to the HttpServletRequest attributes. This is because the Servlet container forwarded to your index.jsp directly.

不要这样做，而是创建一个新的 @Controller 处理程序方法，它将向模型添加一个属性并转发到 index.jsp 视图.

Instead of doing that, create a new @Controller handler method which will added an attribute to the model and forward to the index.jsp view.

@RequestMapping(value = "/", method = RequestMethod.GET)
public String welcomePage(Model model) {
    model.addAttribute("category", new Category()); // the Category object is used as a template to generate the form
    return "index";
}

你可以摆脱这个

<!--  Set the default page as index.jsp -->
<mvc:view-controller path="/" view-name="index"/>

另外，将任何 mvc 配置从您的 applicationContext.xml 文件移动到您的 servlet-context.xml 文件.那就是它的归属.原因如下.

Also, move any mvc configuration from your applicationContext.xml file to your servlet-context.xml file. That's where it belongs. Here's why.

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