Question

每当我尝试使用entitymanager使用@PersistenceContext注释时，它都为空。我正在使用glassfish服务器4.1：我在日志中获得了这个信息：

Infos:   Building JPA container EntityManagerFactory for persistence unit       'webservice'
Infos:   HHH000204: Processing PersistenceUnitInfo [
name: webservice
...]

我的applicationContext如下：

<tx:annotation-driven />
<context:annotation-config />

<!--EntityManager factory--> 

<bean id="emf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    <property name="dataSource" ref="dataSource" />
    <property name="persistenceUnitName" value="webservice" />
    <property name="packagesToScan" value="org.project.domain" />
    <property name="jpaVendorAdapter">
        <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
    </property>
    <property name="jpaProperties">
        <props>                
            <prop key="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</prop>
        </props>
    </property>
</bean>

<!--Datasource--> 

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="org.postgresql.Driver" />
    <property name="url" value="jdbc:postgresql://localhost:5432/testdb" />
    <property name="username" value="postgres" />
    <property name="password" value="admin" />
</bean>

<!--Transaction manager-->                                    
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="emf" />
</bean>  

 <!--Beans definition-->  
<bean id="persistenceExceptionTranslationPostProcessor"
      class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />

<bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor"/>

我的存储库类如下：

 @Repository
 @Qualifier("studentRepository")
 public class StudentRepository implements IStudentRepository {

@PersistenceContext(unitName ="webservice")
private EntityManager em;

public StudentRepository() {
}

@Transactional
@Override
public Student findByUsername(String username) {
    System.out.println(em == null);
    Query q = em.createNamedQuery("Student.findByUsername");
    q.setParameter("username", username);
    try {
        Student s = (Student) q.getSingleResult();
        System.out.println(s.toString());
        return (Student) q.getSingleResult();
    } catch (Exception e) {
        return null;
    }
}

每当我尝试：

  System.out.println(em == null);

返回true，然后返回Null指针异常。

我错过了什么吗？

编辑1

这是我的POM.xml：

 <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>4.2.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>4.2.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-beans</artifactId>
        <version>4.2.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-web</artifactId>
        <version>4.2.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>4.2.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
        <version>4.2.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aop</artifactId>
        <version>4.2.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-tx</artifactId>
        <version>4.2.0.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context-support</artifactId>
        <version>4.2.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-orm</artifactId>
        <version>4.2.1.RELEASE</version>
    </dependency>
    <!--   <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-jpa</artifactId>
        <version>1.9.1.RELEASE</version>
    </dependency>-->

    <!--========================================================================================================
                                                SPRING SECURITY DEPENDENCIES
    ========================================================================================================-->  

    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-config</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-web</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-core</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security.oauth</groupId>
        <artifactId>spring-security-oauth2</artifactId>
        <version>2.0.7.RELEASE</version>
    </dependency>

    <!--========================================================================================================
                                                JERSEY DEPENDENCIES
    ========================================================================================================-->  

    <dependency>
        <groupId>javax.ws.rs</groupId>
        <artifactId>javax.ws.rs-api</artifactId>
        <version>2.0.1</version>
    </dependency>

    <dependency>
        <groupId>com.sun.jersey.contribs</groupId>
        <artifactId>jersey-multipart</artifactId>
        <version>1.19</version>
    </dependency>
    <dependency>
        <groupId>com.sun.jersey</groupId>
        <artifactId>jersey-core</artifactId>
        <version>1.19</version>
    </dependency>
    <dependency>
        <groupId>com.sun.jersey</groupId>
        <artifactId>jersey-bundle</artifactId>
        <version>1.19</version>
    </dependency>

    <dependency>
        <groupId>com.sun.jersey.contribs</groupId>
        <artifactId>jersey-spring</artifactId>
        <version>1.9.1</version>
        <exclusions>
            <exclusion>
                <groupId>org.springframework</groupId>
                <artifactId>spring</artifactId>
            </exclusion>
            <exclusion>
                <groupId>org.springframework</groupId>
                <artifactId>spring-core</artifactId>
            </exclusion>
            <exclusion>
                <groupId>org.springframework</groupId>
                <artifactId>spring-web</artifactId>
            </exclusion>
            <exclusion>
                <groupId>org.springframework</groupId>
                <artifactId>spring-beans</artifactId>
            </exclusion>
            <exclusion>
                <groupId>org.springframework</groupId>
                <artifactId>spring-context</artifactId>
            </exclusion>
            <exclusion>
                <groupId>org.springframework</groupId>
                <artifactId>spring-aop</artifactId>
            </exclusion>
            <exclusion>
                <groupId>org.springframework</groupId>
                <artifactId>spring-asm</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

    <!--========================================================================================================
                                      HIBERNATE DEPENDECIES
    ========================================================================================================-->  

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>4.3.1.Final</version> 
    </dependency>


    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-jpamodelgen</artifactId>
        <version>4.3.1.Final</version>
    </dependency>

    <!--========================================================================================================
                                      OTHER DEPENDECIES
    ========================================================================================================-->
    <dependency>
        <groupId>org.glassfish.web</groupId>
        <artifactId>javax.servlet.jsp.jstl</artifactId>
        <version>1.2.2</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.10</version>
        <scope>test</scope>
    </dependency>

    <dependency>
        <groupId>unknown.binary</groupId>
        <artifactId>org-apache-commons-logging</artifactId>
        <version>SNAPSHOT</version>
    </dependency>
    <dependency>
        <groupId>unknown.binary</groupId>
        <artifactId>cglib-2.2</artifactId>
        <version>SNAPSHOT</version>
    </dependency>
    <dependency>
        <groupId>javax</groupId>
        <artifactId>javaee-web-api</artifactId>
        <version>7.0</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>${mysql-connector-java.version}</version>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.postgresql</groupId>
        <artifactId>postgresql</artifactId>
        <version>9.4-1205-jdbc4</version>
    </dependency>

    <dependency>
        <groupId>org.modelmapper</groupId>
        <artifactId>modelmapper</artifactId>
        <version>0.7.4</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-annotations</artifactId>
        <version>2.5.2</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>2.5.2</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.7.13</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <version>1.7.13</version>
    </dependency>


</dependencies>

Answer 1

您还必须在applicationContext中包含组件扫描

<context:component-scan base-package="yourBasePackage"/>

Spring 4和hibernate 4 EntityManager实例为null

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