[SPRING] 봄 + JPA + 최대 절전 모드

봄 + JPA + 최대 절전 모드

나는 봄에 초보자입니다. 스프링 3.1.3 및 JPA 2.0으로 간단한 웹 응용 프로그램을 설치하려고합니다. 필요한 모든 libs를 WEB-INF / lib에 추가했습니다. 시작할 때 오류는 없지만 DaoImpl 파일의 entityManager는 null입니다. 그래서, 이것은 나의 구성입니다 :

이 persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">

<persistence-unit name="fcmsServer" transaction-type="RESOURCE_LOCAL">
</persistence-unit>
</persistence>

fcms-servlet.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" xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx.xsd">

<!-- the application context definition for the fcmsServer DispatcherServlet -->

<bean id="entityManagerFactory"
    class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    <property name="persistenceUnitName" value="fcmsServer" />
    <property name="dataSource" ref="dataSource" />
    <property name="jpaDialect">
        <bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect" />
    </property>
    <property name="jpaVendorAdapter">
        <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
            <property name="showSql" value="true" />
            <property name="generateDdl" value="true" />
            <property name="databasePlatform" value="org.hibernate.dialect.H2Dialect" />
        </bean>
    </property>
    <property name="persistenceUnitManager">
        <bean
            class="org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager">
            <property name="defaultDataSource" ref="dataSource" />
        </bean>
    </property>
</bean>

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
    destroy-method="close">
    <property name="driverClassName" value="org.h2.Driver" />
    <property name="url" value="jdbc:h2:tcp://localhost/~/fcms" />
    <property name="username" value="sa" />
    <property name="password" value="sa" />
</bean>

<tx:annotation-driven transaction-manager="transactionManager" />
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="entityManagerFactory" />
    <property name="dataSource" ref="dataSource" />
</bean>

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


<bean id="userDao" class="fcms.data.user.UserDAOImpl">
</bean>

<bean name="/user.htm" class="fcms.controller.UserController">
</bean>

<bean id="viewResolver"
    class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="viewClass"
        value="org.springframework.web.servlet.view.JstlView"></property>
    <property name="prefix" value="/WEB-INF/jsp/"></property>
    <property name="suffix" value=".jsp"></property>
</bean>

DaoImpl 클래스 :

@Repository
public class UserDAOImpl implements UserDAO {
@PersistenceContext(unitName = "fcmsServer")
private EntityManager entityManager;

public void setEntityManager(EntityManager entityManager) {
    this.entityManager = entityManager;
}

@Override
public User getUserById(long id) {
    return entityManager.find(User.class,id);
}

@Override
public void addUser(User u) {
    entityManager.persist(u);
}
}

사용자 클래스

@Entity
@Table(name = "User")
public class User implements Serializable {


@Id  @GeneratedValue
private long id;
@Column(name = "lastName", nullable = false)
private String lastName;
@Column(name = "firstName", nullable = false)
private String firstName;
@Column(name = "birthDate", nullable = true)
private Date birthDate;
private static final long serialVersionUID = 1L;

}

그래서 UserController에서 addUser ()를 호출하려고하면 persist 동안 NullPointerException이 발생합니다.

해결법

1. ==============================

   1.스프링이 주석을 검색하도록 설정을 잃어 버렸다고 생각합니다 ( 요소 사이에 다음을 추가하십시오.

   스프링이 주석을 검색하도록 설정을 잃어 버렸다고 생각합니다 ( 요소 사이에 다음을 추가하십시오.

   <context:annotation-config />
   

   그리고 DAO가있는 패키지를 다음과 같이 추가해야 할 수도 있습니다. 그러나 나는 이것이 필요하다고 생각하지 않는다.

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

2. ==============================

   2.이것은 코드의 작동 조각입니다 :

   이것은 코드의 작동 조각입니다 :

   Spring.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"
           xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
           xsi:schemaLocation="http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans.xsd
   http://www.springframework.org/schema/context
   http://www.springframework.org/schema/context/spring-context.xsd
   http://www.springframework.org/schema/tx 
   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">
           <context:annotation-config />
           <context:component-scan base-package="com.package.dao" />
           <tx:annotation-driven transaction-manager="transactionManager" />
           <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean">
                   <property name="persistenceUnitName" value="fcmsServer" />
           </bean>
           <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
                   <property name="entityManagerFactory" ref="entityManagerFactory" />
           </bean>        
   </beans> 
   

   DAO 빈 :

   @Repository
   public class UserDaoBean implements UserDao {
           @PersistenceContext
           protected EntityManager em;         
   }
   

   Persistence.xml :

   <?xml version="1.0" encoding="UTF-8" ?>
   <persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
                version="1.0">
       <persistence-unit name="fcmsServer" transaction-type="RESOURCE_LOCAL">
   
           <class>com.package.entity.</class>
           <properties>
               <property name="javax.persistence.jdbc.url"
                    value="jdbc:mysql://localhost:3306/db_name"/>
               <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
               <property name="javax.persistence.jdbc.user" value="admin"/>
               <property name="javax.persistence.jdbc.password" value="admin"/>
           </properties>
       </persistence-unit>
   </persistence>
   

from https://stackoverflow.com/questions/14855181/spring-jpa-hibernate by cc-by-sa and MIT license