Spring 整合 JPA 完整範例：實體類、DAO、配置與 CRUD 測試

專案結構概覽

• Entity：org.shirdrn.entity.MyUser（JPA 註解映射）
• DAO Interface：org.shirdrn.dao.MyUserDAO（@Transactional）
• DAO Impl：org.shirdrn.dao.impl.MyUserDAOImpl（繼承 JpaDaoSupport）
• Spring Config：applicationContext.xml + META-INF/persistence.xml
• 測試類：org.shirdrn.test.*

1. 實體類 MyUser

@Entity
public class MyUser {
    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name="userName") private String userName;
    @Column(name="password") private String password;
    @Column(name="gender")   private String gender;
    @Column(name="age")      private Integer age;
    @Column(name="addr")     private String addr;
    @Column(name="email")    private String email;

    @Transient // 不映射資料庫欄位
    private Integer birthYear;

    // Getter/Setter 略
    public Integer getBirthYear() { return 2008 - age; }
}

2. DAO 介面與實作

@Transactional
public interface MyUserDAO {
    void createMyUser(MyUser u);
    void deleteMyUser(MyUser u);
    void updateMyUser(MyUser u);
    List queryMyUser(String jpql);
    List queryAll();
}

public class MyUserDAOImpl extends JpaDaoSupport implements MyUserDAO {
    public void createMyUser(MyUser u) { getJpaTemplate().persist(u); }
    public void deleteMyUser(MyUser u) {
        MyUser db = getJpaTemplate().find(MyUser.class, u.getId());
        getJpaTemplate().remove(db);
    }
    public void updateMyUser(MyUser u) {
        MyUser db = getJpaTemplate().find(MyUser.class, u.getId());
        if (u.getUserName() != null) db.setUserName(u.getUserName());
        if (u.getAddr() != null) db.setAddr(u.getAddr());
        getJpaTemplate().merge(db);
    }
    public List queryMyUser(String jpql) { return getJpaTemplate().find(jpql); }
    public List queryAll() { return getJpaTemplate().find("from MyUser"); }
}

3. Spring 配置 applicationContext.xml

<beans xmlns="https://www.springframework.org/schema/beans"
       xmlns:tx="https://www.springframework.org/schema/tx"
       xsi:schemaLocation=".../spring-beans-2.0.xsd .../spring-tx-2.0.xsd">

  <bean id="entityManagerFactory"
        class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    <property name="dataSource" ref="dataSource"/>
    <property name="jpaVendorAdapter">
        <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
            <property name="showSql" value="true"/>
        </bean>
    </property>
  </bean>

  <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="entityManagerFactory"/>
  </bean>

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

  <bean id="myUserDAOImpl" class="org.shirdrn.dao.impl.MyUserDAOImpl">
    <property name="entityManagerFactory" ref="entityManagerFactory"/>
  </bean>
</beans>

4. JPA 配置 META-INF/persistence.xml

<persistence xmlns="https://java.sun.com/xml/ns/persistence" version="1.0">
  <persistence-unit name="default">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <class>org.shirdrn.entity.MyUser</class>
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
    </properties>
  </persistence-unit>
</persistence>

5. CRUD 測試範例

// 新增
MyUserDAO dao = ctx.getBean("myUserDAOImpl", MyUserDAO.class);
MyUser u = new MyUser();
u.setUserName("JohnXa"); u.setPassword("123456"); u.setGender("男");
u.setAge(25); u.setAddr("NewYork"); u.setEmail("john@hotmail.com");
dao.createMyUser(u);

// 刪除
MyUser del = new MyUser(); del.setId(29L); dao.deleteMyUser(del);

// 修改
MyUser upd = new MyUser(); upd.setId(28L); upd.setAddr("北京市"); dao.updateMyUser(upd);

// 查詢
List list = dao.queryAll();
for (MyUser user : list) { System.out.println(user.getUserName() + " ..."); }

心得總結

• JPA 註解免去大量 XML 映射檔，關聯關係一目瞭然。
• JpaTemplate API 不如 HibernateTemplate 直觀，修改/刪除需先 find 再操作。
• 查詢簡單強大，但插入/修改/刪除必須在交易中，否則無效。
• 整合門檻較高，錯誤排查不易，適合表格多、關聯複雜的專案。