Spring Data Jpa示例（IntelliJ maven项目）

1. 在IntelliJ中新建maven项目

给出一个建好的示例，（本示例中省略了业务逻辑组件UserService）

2. 在pom.xml中配置依赖

包括：
spring-context
spring-orm
spring-data-jpa
hibernate-core
hibernate-entitymanager
mysql-connector-java
commons-dbcp
junit
spring-test

代码如下：

<dependencies>
    <!-- Spring & Spring Data JPA -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>4.2.3.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-orm</artifactId>
        <version>4.2.3.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-jpa</artifactId>
        <version>1.9.1.RELEASE</version>
    </dependency>

    <!-- Hibernate -->
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>4.3.11.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>4.3.11.Final</version>
    </dependency>

    <!-- MySQL -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.37</version>
    </dependency>
    <dependency>
        <groupId>commons-dbcp</groupId>
        <artifactId>commons-dbcp</artifactId>
        <version>1.4</version>
    </dependency>

    <!-- Junit -->
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-test</artifactId>
        <version>4.2.3.RELEASE</version>
    </dependency>
</dependencies>

3. resources右键new一个Xml Configuration File--Spring Config配置文件：spring-config.xml（或者applicationContext.xml）

    配置dataSource、entityManagerFactory、transactionManager等。

<?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:jpa="http://www.springframework.org/schema/data/jpa"
       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/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">

    <jpa:repositories base-package="com.xin"/>

    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/javaee"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
    </bean>

    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="packagesToScan" value="com.xin"/>
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <property name="database" value="MYSQL"/>
                <property name="generateDdl" value="true"/>
                <property name="showSql" value="true"/>
                <property name="databasePlatform" value="org.hibernate.dialect.MySQL5InnoDBDialect"/>
            </bean>
        </property>
        <property name="jpaProperties">
            <value>
                hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect
                hibernate.hbm2ddl.auto=update
                hibernate.show_sql=true    <!--此处的设置可以覆盖jpaVendorAdapter中的相关设置-->
                <!--hibernate.format_sql=true-->
            </value>
        </property>
    </bean>

    <!--配置针对JPA的局部事务管理器-->
    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory"/>
    </bean>
    <!--根据事务注解来生成事务代理-->
    <tx:annotation-driven transaction-manager="transactionManager"/>
</beans>

4. 新建User实体类，并进行Annotation注解

@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private String firstname, lastname;
    private int age;
    private String address;
//省略构造方法和setter、getter方法
}

5. 新建DAO组件：UserRepository接口

让此接口继承Repository、CrudRepository、PagingAndSortingRepositories 或者 JpaRepository。JpaRepository接口有一实现类SimpleJpaRepository，上述接口声明的方法均由该类实现。

public interface UserRepository extends JpaRepository<User, Long> {
    //可以根据方法名进行衍生查询，也可以自定义查询。
    @Query("select u from User u where u.lastname=?1")
    List<User> findByLastname(String lastname);
    
    Long countByLastname(String lastname);
}

6. 接下来便可使用junit单元测试类进行测试了

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:spring-config.xml")
public class UserRepositoryTest {
    @Autowired
    private UserRepository userRepository;

    @Test
    public void testFindByLastname() throws Exception {
        User user = new User("lunhui","wei",28, "nanle");
        userRepository.save(user);
    }
}