[Java知识库]springdataJPA 一对一

导入依赖

    <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-jpa</artifactId>
    </dependency>
    <!-- https://mvnrepository.com/artifact/junit/junit -->
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <scope>test</scope>
    </dependency>


    <!--hibernate-entitymanager -->
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>5.4.10.Final</version>
    </dependency>
    <!--        mysql-->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.11</version>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.8</version>
    </dependency>
    <!--        连接池-->
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.2.8</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-test</artifactId>
        <version>5.3.18</version>
        <scope>test</scope>
    </dependency>

customer实体类

package com.li.pojo;


import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import javax.persistence.*;

@Entity//作为hibernate实体类
@Table(name="customer")
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Customer {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "custId")
    private Long custId;//客户主键
    @Column(name = "custName")
    private String custName;//客户名称
    @Column(name = "custAddress")
    private String custAddress;//客户地址
    //单向关联 一对一
    /**cascade 设置关联操作
     * ALL 所有持久化操作
     * PERSIST 只有插入才会执行关联操作
     * MERGE  只有修改才会执行关联操作
     * REMOVE   只有删除才会执行关联操作
     * fetch是否懒加载
     *  LAZY 懒加载(直到用到对象才会进行查询)
     *  EAGER立即加载（默认）
     * (cascade = CascadeType.ALL,fetch = FetchType.LAZY)
     * orphanRemoval = true 关联移除（通常在修改的时候会用到）
     * 一旦把关联的数据设置为null，或者修改为其他关联数据
     * 如果想要删除关联数据，就可以设置为true
     * optional = false 关联对象不能为null 默认为true 即可以为空
     * mappedBy 将外键约束给另一方维护 值 = 另一方关联属性名(通常在双向关联关系中，会放弃一方的外键约束)
     */
    @OneToOne(cascade = CascadeType.ALL)
    //设置外键的字段名
    @JoinColumn(name = "aid")
    private Account account;
}

?account实体类

package com.li.pojo;

import lombok.*;

import javax.persistence.*;

@Entity
@Data// 相当于写了 @Getter //@Getter @Setter @RequiredArgsConstructor @EqualsAndHashCode
// 生成所有属性的get方法
//@Setter//生成所有属性的set方法
//@RequiredArgsConstructor//生成所有属性的get方法
//@EqualsAndHashCode
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "account")
public class Account {
    @Id
    @Column(name = "aid")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long aid;
    @Column(name = "username")
    private String username;
    @Column(name = "password")
    private String password;

   /*双向关联
   @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "id")
    private Customer customer;*/
}

接口

package com.li.repositories;

import com.li.pojo.Customer;
import org.springframework.data.repository.CrudRepository;
import org.springframework.data.repository.PagingAndSortingRepository;

public interface CustomerRepository extends PagingAndSortingRepository<Customer,Long> {
}

配置类

package com.li.config;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.persistence.EntityManagerFactory;
import javax.sql.DataSource;

@Configuration //标记当前类为配置类 相当于xml配置
@EnableJpaRepositories(basePackages = "com.li.repositories")
//启动 jpa 相当于<jpa:repositories base-package="com.li.repositories"
@EnableTransactionManagement //开启事务
public class SpringDataJPAConfig {
    /*
        <bean class="com.alibaba.druid.pool.DruidDataSource" name="dataSource">
        <property name="username" value="root"></property>
        <property name="password" value="root"></property>
        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver" ></property>
        <property name="url" value="jdbc:mysql://localhost:3306/sprindataJpa?useUnicode=true&amp;characterEncoding=utf8&amp;useSSL=false&amp;serverTimezone=Asia/Shanghai&amp;allowPublicKeyRetrieval=true" ></property>
    </bean>
     */
    @Bean
    public DataSource dataSource() {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setUrl("jdbc:mysql://localhost:3306/sprindataJpa?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai&allowPublicKeyRetrieval=true");
        dataSource.setUsername("root");
        dataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
        dataSource.setPassword("root");
        return dataSource;
    }

    /*
    <bean name="entityManagerFactory"
          class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="jpaVendorAdapter">
<!--            Hibernate实例-->
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
<!--                生成数据库表-->
                <property name="generateDdl" value="true"></property>
                <property name="showSql" value="true"></property>
            </bean>
        </property>
<!--        设置实体类的包名-->
        <property name="packagesToScan" value="com.li.pojo"></property>
        <property name="dataSource" ref="dataSource">
<!--         可以用这种写法   <bean></bean>-->
        </property>
    </bean>
     */
    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {

        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        vendorAdapter.setGenerateDdl(true);
        vendorAdapter.setShowSql(true);
        LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
        factory.setJpaVendorAdapter(vendorAdapter);
        factory.setPackagesToScan("com.li.pojo");
        factory.setDataSource(dataSource());
        return factory;
    }

    /*
     <bean class="org.springframework.orm.jpa.JpaTransactionManager" name="transactionManager">
            <property name="entityManagerFactory" ref="entityManagerFactory"></property>
        </bean>
     */
    @Bean
    public PlatformTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {

        JpaTransactionManager txManager = new JpaTransactionManager();
        txManager.setEntityManagerFactory(entityManagerFactory);
        return txManager;
    }
}

测试类

package com.li;

import com.li.config.SpringDataJPAConfig;
import com.li.pojo.Account;
import com.li.pojo.Customer;
import com.li.repositories.CustomerRepository;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.transaction.annotation.Transactional;

import java.util.Optional;

@ContextConfiguration(classes = SpringDataJPAConfig.class)
@RunWith(SpringJUnit4ClassRunner.class)
public class OneToOneTest {
    @Autowired
    CustomerRepository repository;

    @Test//插入
    public void testC() {
        Account account = new Account();
        account.setPassword("123");
        account.setUsername("admin");
        Customer customer = new Customer();
        customer.setCustName("张三");
        customer.setCustAddress("郑州");
        customer.setAccount(account);
        repository.save(customer);
    }

    @Test//查询
    //为什么要配置事务：
    //当通过repository 调用完查询方法，session就会立即关闭，一旦session关闭你就不能查询
    //加了事务后，就能让session直到事务方法执行完毕之后才关闭
    @Transactional(readOnly = true)
    public void testR() {
        Optional<Customer> byId = repository.findById(1L);//    只查询客户，session关闭
        System.out.println("==============");
        System.out.println(byId.get());
    }

    @Test
    public void testD() {
        repository.deleteById(3L);
    }
    @Test
    public void testU() {
        Customer customer = new Customer();
        customer.setCustId(1L);
        customer.setCustName("xxx");
        customer.setAccount(null);
        repository.save(customer);
    }
}

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