spring BeanCreationException关于映射的混淆 [英] spring BeanCreationException confusion about mapping

问题描述

尝试集成hibernate和spring，我遇到了这个错误

trying to integrate hibernate and spring ,I ran into this error

SEVERE：上下文初始化失败 org。 springframework.beans.factory.BeanCreationException ：创建名称为
' org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping '：bean的初始化失败;嵌套异常是 java.lang.IllegalStateException ：无法映射处理程序' org.me.spring.hib.school.web.SchoolController＃0 '到URL路径[ / allschools ]：已经存在[class org.me.spring.hib.school类型的处理程序。 web.SchoolController ]已映射。

SEVERE: Context initialization failed org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping': Initialization of bean failed; nested exception is java.lang.IllegalStateException: Cannot map handler 'org.me.spring.hib.school.web.SchoolController#0' to URL path [/allschools]: There is already handler of type [class org.me.spring.hib.school.web.SchoolController] mapped.

我的控制器看起来像

package org.me.spring.hib.school.web;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.me.spring.hib.school.dao.SchoolDAO;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

@Controller
public class SchoolController {
    private SchoolDAO schoolDao;

    public SchoolDAO getSchoolDao() {
        return schoolDao;
    }

    public void setSchoolDao(SchoolDAO schoolDao) {
        this.schoolDao = schoolDao;
    }
        @RequestMapping("/allschools")
    public ModelAndView showAllSchools(HttpServletRequest request,HttpServletResponse response) throws Exception{
        if(this.schoolDao ==null){
            System.out.println("this.schoolDao is null");
        }
        ModelMap modelMap = new ModelMap();
        modelMap.addAttribute("schoolsList", this.schoolDao.getAllSchools());
        return new ModelAndView("allschools", modelMap);
    }

}

我已经注入了dao实现应用程序上下文文件

I have injected the dao implementation in app context file

    <context:component-scan base-package="org.me.spring.hib.school.web" />

    <bean id="hibernateTemplate" class="org.springframework.orm.hibernate3.HibernateTemplate"> 
       <property name="sessionFactory" >
           <ref bean="sessionFactory" />
       </property>    
    </bean>

    <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
       <property name="dataSource">
          <ref local="dataSource"/>
       </property>
       <property name="annotatedClasses">
            <list>
                <value>org.me.spring.hib.school.domain.School</value>
                <value>org.me.spring.hib.school.domain.Teacher</value>
                <value>org.me.spring.hib.school.domain.Student</value>
            </list>
       </property>


       <property name="hibernateProperties">
        <props>
                <prop key="hibernate.dialect"> org.hibernate.dialect.HSQLDialect</prop>
                <prop key="hibernate.show_sql">true</prop>
                <prop key="hibernate.hbm2ddl.auto">create</prop>
        </props>
       </property>

   </bean>

    <bean id="schoolDao" class="org.me.spring.hib.school.dao.SchoolDAOImpl">
        <property name="hibernateTemplate" ref="hibernateTemplate" />
    </bean>


    <bean  class="org.me.spring.hib.school.web.SchoolController" >
            <property name="schoolDao" ref="schoolDao" />
    </bean>

我无法弄清楚为什么 SchoolController＃0 被映射到网址。

I cannot make out why SchoolController#0 is being mapped to the url.

推荐答案

这种情况正在发生，因为你有两个

This is happening because you have both

<context:component-scan base-package="org.me.spring.hib.school.web" />

和

<bean  class="org.me.spring.hib.school.web.SchoolController" >

第一行将自动发现并注册 SchoolController 为你服务。通过明确声明另一个，你得到一个副本，url-mapping将发生冲突。

The first line will auto-discover and register a SchoolController for you. By explicitly declaring another one, you get a duplicate, and the url-mapping will clash.

你需要删除< context： component-scan> ，或删除控制器和DAO的显式bean定义。如果您执行后者，则需要使用自动装配来注入其依赖项。

You need to either remove the <context:component-scan>, or remove the explicit bean definitions for the controller and the DAO. If you do the latter, then you'll need to use autowiring to inject their dependencies.

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