Spring环境下配置SpringData JPA

旧城等待， 2021-11-01 10:32 265阅读 0赞

### Spring 环境下配置SpringData JPA ###

*  前言
 *  基本环境搭建
 *  创建实体类
 *  创建配置文件
 *  测试

# 前言 #

在 Spring Boot 中，Spring Data JPA 官方封装了太多东西了，导致很多人用的时候不知道底层到底是怎么配置的，本文就和大伙来看看在手工的Spring环境下，Spring Data Jpa要怎么配置，配置完成后，用法和 Spring Boot 中的用法是一致的。

# 基本环境搭建 #

首先创建一个maven工程，导入如下依赖：

<dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-oxm</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aspects</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.27</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-expression</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.2.12.Final</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-jpamodelgen</artifactId>
            <version>5.2.12.Final</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.0.29</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-jpa</artifactId>
            <version>1.11.3.RELEASE</version>
        </dependency>
    </dependencies>

这里除了jpa的依赖外，就是Spring Data JPA的依赖了

# 创建实体类 #

@Entity(name = "t_user")
    public class User { 
        private Integer id;
        private String username;
        private Integer age;
    
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        public Integer getId() { 
            return id;
        }
        // 省略其他getter/setter
    
        public void setId(Integer id) { 
            this.id = id;
        }
    
        public String getUsername() { 
            return username;
        }
    
        public void setUsername(String username) { 
            this.username = username;
        }
    
        public Integer getAge() { 
            return age;
        }
    
        public void setAge(Integer age) { 
            this.age = age;
        }
    
        @Override
        public String toString() { 
            return "User{" +
                    "id=" + id +
                    ", username='" + username + '\'' +
                    ", age=" + age +
                    '}';
        }
    }

# 创建配置文件 #

创建数据库配置文件db.properties

db.driver=com.mysql.jdbc.Driver
    db.url=jdbc:mysql:///test01?useUnicode=true&characterEncoding=UTF-8
    db.username=root
    db.password=1234

接下来在resources目录下创建一个applicationContext.xml文件，并配置Spring和Jpa，如下：

<?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" xmlns:jpa="http://www.springframework.org/schema/data/jpa" 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 http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd">
        <context:property-placeholder location="classpath:db.properties"/>
        <context:component-scan base-package="com.yjn"/>
        <bean class="com.alibaba.druid.pool.DruidDataSource" id="dataSource">
            <property name="driverClassName" value="${db.driver}"/>
            <property name="url" value="${db.url}"/>
            <property name="username" value="${db.username}"/>
            <property name="password" value="${db.password}"/>
        </bean>
        <bean class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean" id="entityManagerFactory">
            <property name="dataSource" ref="dataSource"/>
            <property name="jpaVendorAdapter">
                <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"/>
            </property>
            <property name="packagesToScan" value="com.yjn.bean"/>
            <property name="jpaProperties">
                <props>
                    <prop key="hibernate.show_sql">true</prop>
                    <prop key="hibernate.format_sql">true</prop>
                    <prop key="hibernate.hbm2ddl.auto">update</prop>
                    <prop key="hibernate.dialect">org.hibernate.dialect.MySQL57Dialect</prop>
                </props>
            </property>
        </bean>
        <bean class="org.springframework.orm.jpa.JpaTransactionManager" id="transactionManager">
            <property name="entityManagerFactory" ref="entityManagerFactory"/>
        </bean>
        <tx:annotation-driven transaction-manager="transactionManager"/>
        
        <jpa:repositories base-package="com.yjn.dao" entity-manager-factory-ref="entityManagerFactory"/>
    </beans>

这里和 Jpa 相关的配置主要是三个，一个是entityManagerFactory，一个是Jpa的事务，还有一个是配置dao的位置，配置完成后，就可以在 com.yjn.dao 包下创建相应的 Repository 了，如下：

public interface UserDao extends Repository<User, Integer> { 
        User getUserById(Integer id);
    }

getUserById表示根据id去查询User对象，只要我们的方法名称符合类似的规范，就不需要写SQL，具体的规范一会来说。好了，接下来，创建 Service 和 Controller 来调用这个方法，如下：

@Service
    @Transactional
    public class UserService { 
        @Resource
        UserDao userDao;
    
        public User getUserById(Integer id) { 
            return userDao.getUserById(id);
        }
    }

public void test1() { 
            ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
            UserService userService = ctx.getBean(UserService.class);
            User user = userService.getUserById(1);
            System.out.println(user);
        }

# 测试 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lqbjE5OTU_size_16_color_FFFFFF_t_70]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lqbjE5OTU_size_16_color_FFFFFF_t_70]: /images/20211101/75e9adb829624853ae8168f5e6f71458.png