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我正在尝试集成 Struts 2、Spring 3（用于 DI）、Hibernate 4。 Spring 似乎进行了注入，但是在执行方法中引用注入的对象时，它会引发空指针异常。

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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">

<filter>
     <filter-name>struts2</filter-name>
     <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
</filter>

<filter-mapping>
    <filter-name>struts2</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>


<context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/classes/SpringBeans.xml</param-value>
 </context-param>

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

</web-app>

applicationcontext.xml 命名为 SpringBeans.xml

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

<!-- Database Configuration -->
<import resource="DataSource.xml"/>
<import resource="HibernateSessionFactory.xml"/>

<!-- Beans Declaration -->
<import resource="EmployeeBean.xml"/>

 </beans>

HibernateSessionFactory.xml

<?xml version="1.0" encoding="UTF-8"?> 
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

<bean id="sessionFactory"   class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">

<property name="dataSource">
  <ref bean="dataSource"/>
</property>

<property name="hibernateProperties">
   <props>
     <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
     <prop key="hibernate.show_sql">true</prop>
   </props>
</property>

<property name="mappingResources">
    <list>
      <value>com/example/bean/Employee.hbm.xml</value>
    </list>
</property> 

</bean>
</beans>

EmployeeBean.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans  http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

<bean id="registerAction" class="com.example.register.action.RegisterAction">
    <property name="registerBO" ref="registerBO" /> 
</bean>

<bean id="registerBO" class="com.example.boimplementation.RegisterBOImpl" >
    <property name="employeeDAO" ref="employeeDAO" />
</bean>

<bean id="employeeDAO" class="com.example.daoimplementation.EmployeeDAOImpl" >
    <property name="sessionFactory" ref="sessionFactory" />
</bean>
</beans>

Struts.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"  "http://struts.apache.org/dtds/struts-2.0.dtd">

<struts>
<constant name="struts.action.extension" value=","/>
<constant name="struts.enable.DynamicMethodInvocation"
    value="false" />
<constant name="struts.devMode" value="false" />
<constant name="struts.custom.i18n.resources" value="global" />

<package name="register" namespace="/" extends="struts-default">

    <action name="register" class="com.example.register.action.RegisterAction"
        method="executeAction">

      <result name="success">pages/register.jsp</result>
      <result name="error">pages/register.jsp</result>

    </action>


     <action name="" class="com.example.register.action.RegisterAction"
        method="returnMethod">
             <result name="success">pages/register.jsp</result>
     </action>
</package>

</struts>

动作类

        package com.example.register.action;

    import com.opensymphony.xwork2.ModelDriven;
    import com.example.bean.Employee;
    import com.example.bointerface.RegisterBO;

    public class RegisterAction implements ModelDriven<Employee>{
        RegisterBO registerBO;
        String test;

        private Employee emp = new Employee();

        public void setRegisterBO(RegisterBO registerBO){
            //registerBO.registerEmployee(emp);

            this.registerBO = registerBO;
            test = "Hello!!";
        }

        public RegisterBO getRegisterBO(){
            return registerBO;
        }

        public String executeAction(){
            System.out.println(test);

            if(registerBO.registerEmployee(emp))
                return "success";
            else
                return "error";
        }

        public String returnMethod(){
            return "success";
        }

        @Override
        public Employee getModel() {
            // TODO Auto-generated method stub
            return emp;

        }


    }

在上述操作中，setRegisterBO() 被调用，但是在 executeAction() 中引用 registerBO 对象时，它抛出空指针异常，并且测试字符串变量也打印空。有人可以告诉我在这里做错了什么。

4

0 回答 0