十三关联映射操作-一对多的关联关系

xiaoxiao2022-06-24 177

需求：从角色到用户的一对多的关联关系

角色：一方

用户：多方

创建项目09-spring-data-jpa-onetomany

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.bjsxt</groupId> <artifactId>09-spring-data-jpa-onetomany</artifactId> <version>0.0.1-SNAPSHOT</version> <properties> <java.version>1.8</java.version> <spring.version>4.3.23.RELEASE</spring.version> <hibernate.version>5.1.17.Final</hibernate.version> <mysql.version>5.1.47</mysql.version> <c3p0.version>0.9.2.1</c3p0.version> <junit.version>4.12</junit.version> <lombok.version>1.18.6</lombok.version> <hibernate-entitymanager.version>5.0.7.Final</hibernate-entitymanager.version> <spring-data-jpa.version>1.7.0.RELEASE</spring-data-jpa.version> </properties> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-aspects</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-aop</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jdbc</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-orm</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-core</artifactId> <version>${hibernate.version}</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>${mysql.version}</version> </dependency> <dependency> <groupId>com.mchange</groupId> <artifactId>c3p0</artifactId> <version>${c3p0.version}</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>${junit.version}</version> <scope>test</scope> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <version>${lombok.version}</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-entitymanager</artifactId> <version>${hibernate-entitymanager.version}</version> </dependency> <dependency> <groupId>org.springframework.data</groupId> <artifactId>spring-data-jpa</artifactId> <version>${spring-data-jpa.version}</version> </dependency>  <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.17</version> </dependency> </dependencies> </project>

jdbc.properties

jdbc.url=jdbc:mysql://localhost:3306/spring-data-test?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT #jdbc.url=jdbc:mysql://localhost:3306/spring-data-test 这个保存到数据库中会导致乱码 jdbc.driver.class=com.mysql.jdbc.Driver jdbc.username=root jdbc.password=123456

applicationContext.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:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context" 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 https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.11.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd">  <context:property-placeholder location="classpath:jdbc.properties" />  <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"> <property name="jdbcUrl" value="${jdbc.url}" /> <property name="driverClass" value="${jdbc.driver.class}" /> <property name="user" value="${jdbc.username}" /> <property name="password" value="${jdbc.password}" /> </bean>  <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="database" value="MYSQL" />  <property name="generateDdl" value="true" />  <property name="showSql" value="true" /> </bean> </property>  <property name="packagesToScan"> <list> <value>com.bjsxt.pojo</value> </list> </property> </bean>  <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory" ref="entityManagerFactory" /> </bean>  <tx:annotation-driven transaction-manager="transactionManager"/>  <context:component-scan base-package="com.bjsxt"></context:component-scan>  <jpa:repositories base-package="com.bjsxt.dao"></jpa:repositories> </beans>

1 编写实体类

package com.bjsxt.pojo; import java.io.Serializable; import javax.persistence.CascadeType; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.ManyToOne; import javax.persistence.Table; @Entity @Table(name="ts_users") public class Users implements Serializable{ /** * */ private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy=GenerationType.IDENTITY) @Column(name="id") private Long id; @Column(name="user_name") private String userName; @Column(name="age") private Integer age; @ManyToOne(cascade=CascadeType.ALL) @JoinColumn(name = "role_id") private Roles roles; public Long getId() { return id; } public void setId(Long 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; } public Roles getRoles() { return roles; } public void setRoles(Roles roles) { this.roles = roles; } @Override public String toString() { return "Users [id=" + id + ", userName=" + userName + ", age=" + age + "]"; } } package com.bjsxt.pojo; import java.util.HashSet; import java.util.Set; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.OneToMany; import javax.persistence.Table; /** * * @author guozi * */ @Entity @Table(name = "ts_roles") public class Roles { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "role_id") private Long roleId; @Column(name = "role_name") private String roleName; // mappedBy:users中指定的roles属性 @OneToMany(mappedBy = "roles") private Set<Users> users = new HashSet<>(); public Long getRoleId() { return roleId; } public void setRoleId(Long roleId) { this.roleId = roleId; } public String getRoleName() { return roleName; } public void setRoleName(String roleName) { this.roleName = roleName; } public Set<Users> getUsers() { return users; } public void setUsers(Set<Users> users) { this.users = users; } @Override public String toString() { return "Roles [roleId=" + roleId + ", roleName=" + roleName + "]"; } }

2 创建dao接口

package com.bjsxt.dao; import org.springframework.data.jpa.repository.JpaRepository; import com.bjsxt.pojo.Users; /** * JpaRepository接口使用 * JpaRepository是开发中使用最多的接口 * @author guozi * */ public interface UsersDao extends JpaRepository<Users, Long> { }

3 创建测试类

package com.bjsxt.dao; 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 com.bjsxt.pojo.Roles; import com.bjsxt.pojo.Users; @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration("classpath:applicationContext.xml") public class OneToManyTest { @Autowired private UsersDao usersDao; /** * 保存 * Hibernate: insert into ts_roles (role_name) values (?) Hibernate: insert into ts_users (age, role_id, user_name) values (?, ?, ?) 注意：此处如果实体类用的时lombok时，会报java.lang.StackOverflowError异常，所以将原有的使用lombok去掉，改成setter和getter及toString处理，请参考https://www.jianshu.com/p/d6bb1c343146 */ @Test public void test() { // 创建角色 Roles role = new Roles(); role.setRoleName("船员"); // 创建用户 Users user = new Users(); user.setAge(10); user.setUserName("乔巴"); // 建立关系 user.setRoles(role); role.getUsers().add(user); // 保存数据 this.usersDao.save(user); } /** * 查询 * Hibernate: select users0_.id as id1_1_0_, users0_.age as age2_1_0_, users0_.role_id as role_id4_1_0_, users0_.user_name as user_nam3_1_0_, roles1_.role_id as role_id1_0_1_, roles1_.role_name as role_nam2_0_1_ from ts_users users0_ left outer join ts_roles roles1_ on users0_.role_id=roles1_.role_id where users0_.id=? Users [id=15, userName=乔巴, age=10] Roles [roleId=2, roleName=船员] */ @Test public void test2 () { Users users = this.usersDao.findOne(15l); System.out.println(users); System.out.println(users.getRoles()); } }

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十三 关联映射操作-一对多的关联关系

专利

十三关联映射操作-一对多的关联关系