Java Hibernate查询时出现空指针异常

我正在尝试执行一个hibernate查询，我使用的是JSF2PrimeFaces、SpringSecurity3和Hibernate4。我已经检查了hibernate是否与数据库通信，因为它能够在启动程序时自动创建表

我尝试获取当前会话，并在执行查询时创建会话，但我不知道这是否是原因。我已经搜索并尝试了所有可能的解决方案，但没有找到一个。 我总是遇到以下错误：

错误：

Query query = sessionFactory.getCurrentSession().createQuery(
            "from Holas");

    @Named
@Scope("session")
public class HolasBean{


HolasBo holasBo;
HolasDao holasDao;

public void setUserBo(HolasBo holasBo) {
    this.holasBo = holasBo;
}

public String printMsgFromSpring() {          //This works

    return "HOla";

}
public String getMessage(){                  //Null pointer exception

    return holasDao.getMessageHiber();
}

com.sun.faces.mgbean.ManagedBeanCreationException:无法在com.sun.faces.mgbean.BeanBuilder.newBeanInstance（BeanBuilder.java:193）上实例化类：core.bean.HolasBean 在com.sun.faces.mgbean.BeanBuilder.build（BeanBuilder.java:102）上 在com.sun.faces.mgbean.BeanManager.createAndPush（BeanManager.java:409）上 在com.sun.faces.mgbean.BeanManager.create（BeanManager.java:269）上 位于com.sun.faces.el.ManagedBeanELResolver.resolveBean（ManagedBeanELResolver.java:244） 在com.sun.faces.el.ManagedBeanELResolver.getValue（ManagedBeanELResolver.java:116）上

原因：java.lang.NullPointerException 位于core.bean.HolasBean（HolasBean.java:22）

第22行是查询：

Query query = sessionFactory.getCurrentSession().createQuery(
            "from Holas");

    @Named
@Scope("session")
public class HolasBean{


HolasBo holasBo;
HolasDao holasDao;

public void setUserBo(HolasBo holasBo) {
    this.holasBo = holasBo;
}

public String printMsgFromSpring() {          //This works

    return "HOla";

}
public String getMessage(){                  //Null pointer exception

    return holasDao.getMessageHiber();
}

使用可能的最简单示例进行测试：

荷兰豆：

Query query = sessionFactory.getCurrentSession().createQuery(
            "from Holas");

    @Named
@Scope("session")
public class HolasBean{


HolasBo holasBo;
HolasDao holasDao;

public void setUserBo(HolasBo holasBo) {
    this.holasBo = holasBo;
}

public String printMsgFromSpring() {          //This works

    return "HOla";

}
public String getMessage(){                  //Null pointer exception

    return holasDao.getMessageHiber();
}

HolasDao

@Repository
public class HolasDaoImpl implements HolasDao {

    @Autowired
     private SessionFactory sessionFactory;

    public String getMessageHiber() {
        List<Holas> holas = new ArrayList<Holas>();
        holas = sessionFactory.getCurrentSession().createQuery("from Holas").list();

        return holas.get(0).toString();
 }
}

XHTML

<h:body>

        <h1>JSF 2.0 + Spring Example</h1>

    #{holasBean.printMsgFromSpring()}  //This is working
    #{holasBean.getMessage()}          //Null Pointer Exception

    </h:body>

JSF2.0+Spring示例
#{holasBean.printMsgFromSpring（）}//这正在工作
#{holasBean.getMessage（）}//空指针异常

*编辑*：

Sergey当我发表评论时，我在网站上看到这个错误：

在core.bean.HolasBean类型中找不到属性“holas”

配置文件，以备需要：

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">

<display-name>Project Name</display-name>

<!-- Spring Context Configuration' s Path definition -->

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

<!-- SPRING SECURITY -->

<filter>
    <filter-name>springSecurityFilterChain</filter-name>
    <filter-class>org.springframework.web.filter.DelegatingFilterProxy
    </filter-class>
</filter>

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

<!-- Spring listener. It is registered to Servlet Container -->

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

<!-- Project Stage Level -->

<context-param>
    <param-name>javax.faces.PROJECT_STAGE</param-name>
    <param-value>Development</param-value>
</context-param>

<!-- Welcome Page -->

<welcome-file-list>
    <welcome-file>index.xhtml</welcome-file>
</welcome-file-list>

<!-- JSF Servlet  -->

<servlet>
    <servlet-name>Faces Servlet</servlet-name>
    <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>

<!-- Mapping for the http requests. -->
<servlet-mapping>
    <servlet-name>Faces Servlet</servlet-name>
    <url-pattern>*.jsf</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>Faces Servlet</servlet-name>
    <url-pattern>*.faces</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>Faces Servlet</servlet-name>
    <url-pattern>*.xhtml</url-pattern>
</servlet-mapping>

</web-app>

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

<!-- SPRING SECURITY -->    

<security:http use-expressions="true">
    <security:intercept-url pattern="/secured/*" access="isAuthenticated()"/>
    <security:form-login login-page="/index.xhtml" authentication-failure-url="/malvamos" default-target-url="/aleadormir"/>
    <security:logout logout-success-url="/index"/>
</security:http>

<security:authentication-manager>
    <security:authentication-provider user-service-ref="userServiceImpl" />
</security:authentication-manager>


<bean class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping" />

<mvc:annotation-driven />
<task:annotation-driven />
<context:annotation-config/>
<context:component-scan base-package="core" />



<!-- TRANSACTION MANAGERS -->

<tx:annotation-driven transaction-manager="txManager"/>

<bean id="txManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager">
    <property name="sessionFactory" ref="sessionFactory" />
</bean>



<!-- DATA SOURCES -->

<bean   id="propertyConfigurer"
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"
        p:location="/WEB-INF/connection.properties" />

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="${cnn.driver}" />
    <property name="url" value="${cnn.url}" />
    <property name="username" value="${cnn.username}" />
    <property name="password" value="${cnn.password}" />
</bean>




<!-- SESSION FACTORIES -->

<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
    <property name="dataSource"><ref bean="dataSource"/></property>
    <property name="configLocation">
        <value>/WEB-INF/hibernate-config.xml</value>
    </property>
    <property name="annotatedClasses">
        <list>
            <value>core.model.Permission</value>
            <value>core.model.Role</value>
            <value>core.model.UserEntity</value>
            <value>core.model.Holas</value>
        </list>
    </property>
    <property name="hibernateProperties">
        <props>
            <prop key="hibernate.dialect">
                ${cnn.dialect}
            </prop>
        </props>
    </property>
</bean>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com</groupId>
<artifactId>web</artifactId>
<packaging>war</packaging>
<version>1.0-SNAPSHOT</version>
<name> Maven Webapp</name>
<url>http://maven.apache.org</url>
<properties>
    <hibernate.version>4.1.7.Final</hibernate.version>
    <spring.version>3.1.1.RELEASE</spring.version>
</properties>

<dependencies>

    <!-- Spring 3 dependencies -->

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-web</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-tx</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-orm</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-test</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <!-- SPRING SECURITY -->

    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-core</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-web</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-config</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-taglibs</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <!-- JSF dependencies -->

    <dependency>
        <groupId>com.sun.faces</groupId>
        <artifactId>jsf-api</artifactId>
        <version>2.1.6</version>
    </dependency>

    <dependency>
        <groupId>com.sun.faces</groupId>
        <artifactId>jsf-impl</artifactId>
        <version>2.1.6</version>
    </dependency>

    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
    </dependency>

    <!-- Primefaces dependency -->

    <dependency>
        <groupId>org.primefaces</groupId>
        <artifactId>primefaces</artifactId>
        <version>4.0</version>
    </dependency>

    <!-- Hibernate dependencies -->

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>4.1.7.Final</version>
    </dependency>

    <!-- MySQL Java Connector dependency -->

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.17</version>
    </dependency>

    <!-- c3p0 dependency -->

    <dependency>
        <groupId>c3p0</groupId>
        <artifactId>c3p0</artifactId>
        <version>0.9.1.2</version>
    </dependency>

</dependencies>

<repositories>
    <repository>
        <id>prime-repo</id>
        <name>PrimeFaces Maven Repository</name>
        <url>http://repository.primefaces.org</url>
        <layout>default</layout>
    </repository>
</repositories>
<build>
    <finalName>gesmo</finalName>
</build>
</project>

项目名称
上下文配置位置
/WEB-INF/applicationContext.xml
springSecurityFilterChain
org.springframework.web.filter.DelegatingFilterProxy
springSecurityFilterChain
/*
org.springframework.web.context.ContextLoaderListener
org.springframework.web.context.request.RequestContextListener
javax.faces.PROJECT_阶段
发展
index.xhtml
Facesservlet
javax.faces.webapp.FacesServlet
1.
Facesservlet
*.jsf
Facesservlet
*.面孔
Facesservlet
*.xhtml

aplicationConfig.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">

<display-name>Project Name</display-name>

<!-- Spring Context Configuration' s Path definition -->

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

<!-- SPRING SECURITY -->

<filter>
    <filter-name>springSecurityFilterChain</filter-name>
    <filter-class>org.springframework.web.filter.DelegatingFilterProxy
    </filter-class>
</filter>

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

<!-- Spring listener. It is registered to Servlet Container -->

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

<!-- Project Stage Level -->

<context-param>
    <param-name>javax.faces.PROJECT_STAGE</param-name>
    <param-value>Development</param-value>
</context-param>

<!-- Welcome Page -->

<welcome-file-list>
    <welcome-file>index.xhtml</welcome-file>
</welcome-file-list>

<!-- JSF Servlet  -->

<servlet>
    <servlet-name>Faces Servlet</servlet-name>
    <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>

<!-- Mapping for the http requests. -->
<servlet-mapping>
    <servlet-name>Faces Servlet</servlet-name>
    <url-pattern>*.jsf</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>Faces Servlet</servlet-name>
    <url-pattern>*.faces</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>Faces Servlet</servlet-name>
    <url-pattern>*.xhtml</url-pattern>
</servlet-mapping>

</web-app>

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

<!-- SPRING SECURITY -->    

<security:http use-expressions="true">
    <security:intercept-url pattern="/secured/*" access="isAuthenticated()"/>
    <security:form-login login-page="/index.xhtml" authentication-failure-url="/malvamos" default-target-url="/aleadormir"/>
    <security:logout logout-success-url="/index"/>
</security:http>

<security:authentication-manager>
    <security:authentication-provider user-service-ref="userServiceImpl" />
</security:authentication-manager>


<bean class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping" />

<mvc:annotation-driven />
<task:annotation-driven />
<context:annotation-config/>
<context:component-scan base-package="core" />



<!-- TRANSACTION MANAGERS -->

<tx:annotation-driven transaction-manager="txManager"/>

<bean id="txManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager">
    <property name="sessionFactory" ref="sessionFactory" />
</bean>



<!-- DATA SOURCES -->

<bean   id="propertyConfigurer"
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"
        p:location="/WEB-INF/connection.properties" />

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="${cnn.driver}" />
    <property name="url" value="${cnn.url}" />
    <property name="username" value="${cnn.username}" />
    <property name="password" value="${cnn.password}" />
</bean>




<!-- SESSION FACTORIES -->

<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
    <property name="dataSource"><ref bean="dataSource"/></property>
    <property name="configLocation">
        <value>/WEB-INF/hibernate-config.xml</value>
    </property>
    <property name="annotatedClasses">
        <list>
            <value>core.model.Permission</value>
            <value>core.model.Role</value>
            <value>core.model.UserEntity</value>
            <value>core.model.Holas</value>
        </list>
    </property>
    <property name="hibernateProperties">
        <props>
            <prop key="hibernate.dialect">
                ${cnn.dialect}
            </prop>
        </props>
    </property>
</bean>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com</groupId>
<artifactId>web</artifactId>
<packaging>war</packaging>
<version>1.0-SNAPSHOT</version>
<name> Maven Webapp</name>
<url>http://maven.apache.org</url>
<properties>
    <hibernate.version>4.1.7.Final</hibernate.version>
    <spring.version>3.1.1.RELEASE</spring.version>
</properties>

<dependencies>

    <!-- Spring 3 dependencies -->

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-web</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-tx</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-orm</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-test</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <!-- SPRING SECURITY -->

    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-core</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-web</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-config</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-taglibs</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <!-- JSF dependencies -->

    <dependency>
        <groupId>com.sun.faces</groupId>
        <artifactId>jsf-api</artifactId>
        <version>2.1.6</version>
    </dependency>

    <dependency>
        <groupId>com.sun.faces</groupId>
        <artifactId>jsf-impl</artifactId>
        <version>2.1.6</version>
    </dependency>

    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
    </dependency>

    <!-- Primefaces dependency -->

    <dependency>
        <groupId>org.primefaces</groupId>
        <artifactId>primefaces</artifactId>
        <version>4.0</version>
    </dependency>

    <!-- Hibernate dependencies -->

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>4.1.7.Final</version>
    </dependency>

    <!-- MySQL Java Connector dependency -->

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.17</version>
    </dependency>

    <!-- c3p0 dependency -->

    <dependency>
        <groupId>c3p0</groupId>
        <artifactId>c3p0</artifactId>
        <version>0.9.1.2</version>
    </dependency>

</dependencies>

<repositories>
    <repository>
        <id>prime-repo</id>
        <name>PrimeFaces Maven Repository</name>
        <url>http://repository.primefaces.org</url>
        <layout>default</layout>
    </repository>
</repositories>
<build>
    <finalName>gesmo</finalName>
</build>
</project>

当您注释这一行（22）时，您没有错误？请尝试调试并在第22行设置断点。这将允许您查看导致异常的实际原因，并让您缩小问题范围。我编辑了评论这句话的帖子，现在我将尝试使debuggingI cant debbug我已经尝试过，但它是一个webapp maven项目，我无法eclipse或尝试调试远程webapp I cant。