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SpringDataJPA-动态查询和多表查询(三)
|框架
阅读量:

Specification动态查询

前提

Dao接口必须继承JpaSpecificationExecutor接口

能够使用动态查询的方法

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 public interface JpaSpecificationExecutor<T> {
   	//根据条件查询一个对象
 	T findOne(Specification<T> spec);	
   	//根据条件查询集合
 	List<T> findAll(Specification<T> spec);
   	//根据条件分页查询
 	Page<T> findAll(Specification<T> spec, Pageable pageable);
   	//排序查询查询
 	List<T> findAll(Specification<T> spec, Sort sort);
   	//统计查询
 	long count(Specification<T> spec);
}

环境搭建

创建项目

引入依赖[配置pom.xml]

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<?xml version="1.0" encoding="UTF-8"?>
<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>cn.itcast</groupId>
    <artifactId>jpa-day2</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <spring.version>5.0.2.RELEASE</spring.version>
        <hibernate.version>5.0.7.Final</hibernate.version>
        <slf4j.version>1.6.6</slf4j.version>
        <log4j.version>1.2.12</log4j.version>
        <c3p0.version>0.9.1.2</c3p0.version>
        <mysql.version>5.1.6</mysql.version>
    </properties>

    <dependencies>
        <!-- junit单元测试 -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

        <!-- spring beg -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.6.8</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</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-context-support</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- spring对orm框架的支持包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- spring end -->

        <!-- hibernate beg -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>${hibernate.version}</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>${hibernate.version}</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>5.2.1.Final</version>
        </dependency>
        <!-- hibernate end -->

        <!-- c3p0 beg -->
        <dependency>
            <groupId>c3p0</groupId>
            <artifactId>c3p0</artifactId>
            <version>${c3p0.version}</version>
        </dependency>
        <!-- c3p0 end -->

        <!-- log end -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>${log4j.version}</version>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${slf4j.version}</version>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <!-- log end -->


        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
        </dependency>

        <!-- spring data jpa 的坐标-->
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-jpa</artifactId>
            <version>1.9.0.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- el beg 使用spring data jpa 必须引入 -->
        <dependency>
            <groupId>javax.el</groupId>
            <artifactId>javax.el-api</artifactId>
            <version>2.2.4</version>
        </dependency>

        <dependency>
            <groupId>org.glassfish.web</groupId>
            <artifactId>javax.el</artifactId>
            <version>2.2.4</version>
        </dependency>
        <!-- el end -->
    </dependencies>

</project>

创建包

cn.itcast.service

cn.itcast.dao

cn.itcast.domain

创建applicationContext.xml

Spring整合Jpa就两步

​ 1.由spring创建entityManagerFactory

​ 2.使用标签jpa:repositories和spring进行整合

提示：该文件应该在java/main/resource目录下

注意修改数据库密码

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<?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:context="http://www.springframework.org/schema/context"
       xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:jpa="http://www.springframework.org/schema/data/jpa" xmlns:task="http://www.springframework.org/schema/task"
       xsi:schemaLocation="
		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
		http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc.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">

<!--S Spring配置[之前课程里的旧东西]-->
    <!--配置扫描包-->
    <context:component-scan base-package="cn.itcast" ></context:component-scan>
    <!--创建数据库连接池 -->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="user" value="root"></property>
        <property name="password" value="root"></property>
        <property name="jdbcUrl" value="jdbc:mysql:///jpa" ></property>
        <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
    </bean>
    <!--配置事务管理器-->
    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <!--这里不需要配置
			<property name="dataSource" ref="dataSource" /> 
			因为数据源已经配置在entityManagerFactory中了
		-->
        <property name="entityManagerFactory" ref="entityManagerFactoty"></property>
    </bean>

    <tx:advice id="txAdvice" transaction-manager="transactionManager">
        <tx:attributes>
            <tx:method name="save*" propagation="REQUIRED"/>
            <tx:method name="insert*" propagation="REQUIRED"/>
            <tx:method name="update*" propagation="REQUIRED"/>
            <tx:method name="delete*" propagation="REQUIRED"/>
            <tx:method name="get*" read-only="true"/>
            <tx:method name="find*" read-only="true"/>
            <tx:method name="*" propagation="REQUIRED"/>
        </tx:attributes>
    </tx:advice>

    <aop:config>
        <aop:pointcut id="pointcut" expression="execution(* cn.itcast.service.*.*(..))" />
        <aop:advisor advice-ref="txAdvice" pointcut-ref="pointcut" />
    </aop:config>
<!--E Spring配置[之前课程里的旧东西]-->







<!--S Spring整合JPA[今天讲的新配置]-->
    <!-- 1.创建entityManagerFactory对象交给spring容器管理-->
    <bean id="entityManagerFactoty" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <!--配置的扫描的包（实体类所在的包） -->
        <property name="packagesToScan" value="cn.itcast.domain" />
        <!-- jpa的实现厂家 -->
        <property name="persistenceProvider">
            <bean class="org.hibernate.jpa.HibernatePersistenceProvider"/>
        </property>

        <!--jpa的供应商适配器 -->
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <!--配置是否自动创建数据库表 -->
                <property name="generateDdl" value="false" />
                <!--指定数据库类型 -->
                <property name="database" value="MYSQL" />
                <!--数据库方言：支持的特有语法 -->
                <property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect" />
                <!--是否显示sql -->
                <property name="showSql" value="true" />
            </bean>
        </property>

        <!--jpa的方言 ：高级的特性 -->
        <property name="jpaDialect" >
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect" />
        </property>
        <property name="jpaProperties" >
            <props>
                <prop key="hibernate.hbm2ddl.auto">update</prop>
            </props>
        </property>
    </bean>

    <!--2.整合spring dataJpa-->
    <jpa:repositories base-package="cn.itcast.dao" transaction-manager-ref="transactionManager"
                      entity-manager-factory-ref="entityManagerFactoty" ></jpa:repositories>
<!--E Spring整合JPA[今天讲的新配置]-->
</beans>

快速入门

创建表cst_customer

提示：day01已经创建过了

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USE `jpa`;
DROP TABLE IF EXISTS `cst_customer`;

CREATE TABLE `cst_customer` (
  `cust_id` bigint(32) NOT NULL AUTO_INCREMENT COMMENT '客户编号(主键)',
  `cust_name` varchar(32) NOT NULL COMMENT '客户名称(公司名称)',
  `cust_source` varchar(32) DEFAULT NULL COMMENT '客户信息来源',
  `cust_industry` varchar(32) DEFAULT NULL COMMENT '客户所属行业',
  `cust_level` varchar(32) DEFAULT NULL COMMENT '客户级别',
  `cust_address` varchar(128) DEFAULT NULL COMMENT '客户联系地址',
  `cust_phone` varchar(64) DEFAULT NULL COMMENT '客户联系电话',
  PRIMARY KEY (`cust_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

insert  into `cst_customer`(`cust_id`,`cust_name`,`cust_source`,`cust_industry`,`cust_level`,`cust_address`,`cust_phone`) values (1,'黑马程序员',NULL,'教育',NULL,NULL,NULL),(2,'传智播客',NULL,'教育',NULL,NULL,NULL),(3,'酷丁鱼',NULL,'教育',NULL,NULL,NULL),(4,'传智汇',NULL,'教育',NULL,NULL,NULL),(5,'传智专修学院',NULL,'教育',NULL,NULL,NULL),(6,'谷歌',NULL,'教育',NULL,NULL,NULL);

创建实体类Customer

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package cn.itcast.domain;
import javax.persistence.*;

public class Customer {
    private Long custId; //客户的主键
    private String custName;//客户名称
    private String custSource;//客户来源
    private String custLevel;//客户级别
    private String custIndustry;//客户所属行业
    private String custPhone;//客户的联系方式
    private String custAddress;//客户地址
    public Long getCustId() {
        return custId;
    }
    public void setCustId(Long custId) {
        this.custId = custId;
    }
    public String getCustName() {
        return custName;
    }
    public void setCustName(String custName) {
        this.custName = custName;
    }
    public String getCustSource() {
        return custSource;
    }
    public void setCustSource(String custSource) {
        this.custSource = custSource;
    }
    public String getCustLevel() {
        return custLevel;
    }
    public void setCustLevel(String custLevel) {
        this.custLevel = custLevel;
    }
    public String getCustIndustry() {
        return custIndustry;
    }
    public void setCustIndustry(String custIndustry) {
        this.custIndustry = custIndustry;
    }

    public String getCustPhone() {
        return custPhone;
    }

    public void setCustPhone(String custPhone) {
        this.custPhone = custPhone;
    }

    public String getCustAddress() {
        return custAddress;
    }

    public void setCustAddress(String custAddress) {
        this.custAddress = custAddress;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "custId=" + custId +
                ", custName='" + custName + '\'' +
                ", custSource='" + custSource + '\'' +
                ", custLevel='" + custLevel + '\'' +
                ", custIndustry='" + custIndustry + '\'' +
                ", custPhone='" + custPhone + '\'' +
                ", custAddress='" + custAddress + '\'' +
                '}';
    }
}

通过注解配置映射关系

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package cn.itcast.domain;

import javax.persistence.*;

@Entity
@Table(name = "cst_customer")
public class Customer {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "cust_id")
    private Long custId; //客户的主键

    @Column(name = "cust_name")
    private String custName;//客户名称

    @Column(name="cust_source")
    private String custSource;//客户来源

    @Column(name="cust_level")
    private String custLevel;//客户级别

    @Column(name="cust_industry")
    private String custIndustry;//客户所属行业

    @Column(name="cust_phone")
    private String custPhone;//客户的联系方式

    @Column(name="cust_address")
    private String custAddress;//客户地址

    public Long getCustId() {
        return custId;
    }

    public void setCustId(Long custId) {
        this.custId = custId;
    }

    public String getCustName() {
        return custName;
    }

    public void setCustName(String custName) {
        this.custName = custName;
    }

    public String getCustSource() {
        return custSource;
    }

    public void setCustSource(String custSource) {
        this.custSource = custSource;
    }

    public String getCustLevel() {
        return custLevel;
    }

    public void setCustLevel(String custLevel) {
        this.custLevel = custLevel;
    }

    public String getCustIndustry() {
        return custIndustry;
    }

    public void setCustIndustry(String custIndustry) {
        this.custIndustry = custIndustry;
    }

    public String getCustPhone() {
        return custPhone;
    }

    public void setCustPhone(String custPhone) {
        this.custPhone = custPhone;
    }

    public String getCustAddress() {
        return custAddress;
    }

    public void setCustAddress(String custAddress) {
        this.custAddress = custAddress;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "custId=" + custId +
                ", custName='" + custName + '\'' +
                ", custSource='" + custSource + '\'' +
                ", custLevel='" + custLevel + '\'' +
                ", custIndustry='" + custIndustry + '\'' +
                ", custPhone='" + custPhone + '\'' +
                ", custAddress='" + custAddress + '\'' +
                '}';
    }
}

创建CustomerDao接口

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package cn.itcast.dao;

import cn.itcast.domain.Customer;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;

/**
 *  JpaRepository<操作的实体类, 实体类中主键的类型> 接口中提供了简单操作数据库的方法
 *  JpaSpecificationExecutorr<操作的是实体类>接口中提供了复杂方法，比如多条件和分页查询
 */
public interface CustomerDao extends JpaRepository<Customer,Long>,
													JpaSpecificationExecutor<Customer>{
}

编写测试类

需求：查询姓名=李四的用户

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package cn.itcast.dao;

import cn.itcast.domain.Customer;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import javax.persistence.criteria.*;
import java.util.List;

/**
 * 针对 CustomerDao 接口的多条件查询演示
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class CustomerDaoSpecificationTest {
    @Autowired
    private CustomerDao customerDao;

    /**
     * 根据客户名进行查询
     */
    @Test
    public void findByCustNameQueryTest(){
        //生成的SQL select * forom cst_customer where cust_name = "李四"
        Customer customer = customerDao.findOne(new Specification<Customer>() {
            @Override
            /**
             * root : 可以获取要操作的属性
             * criteriaBuilder : 构建查询条件
             生成的SQL语句 select * from cst_customer where cust_name =  "李四"
             */
            public Predicate toPredicate(Root<Customer> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
                //custName是Customer实体类的属性的名字，不是表中的字段名
                Path<Object> custName = root.get("custName");
                //添加查询条件 where custName="李四"
                Predicate predicate = criteriaBuilder.equal(custName, "李四");
                return predicate;
            }
        });

        System.out.println(customer);
    }
}

运行结果

单条件查询

请查看1.4内容

多条件查询

需求：查询姓名=李四，电话=1390000000的客户

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/**
 * 多条件查询
 */
@Test
public void manyConditionsQueryTest(){
    Customer customer = customerDao.findOne(new Specification<Customer>() {
        @Override
        /**
        * select * from cst_customer where cust_name ="李四" and  cust_phone = '139xxx'
        */
        public Predicate toPredicate(Root<Customer> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
            //条件1：客户名=李四
            Predicate p1 = criteriaBuilder.equal(root.get("custName"), "李四");
            //条件2：电话=1390000000
            Predicate p2 = criteriaBuilder.equal(root.get("custPhone"), "1390000000");

            //把两个查询条件连接到一起
            ////custName="李四" or custPhone="1390000000"
            //Predicate p3 = criteriaBuilder.or(p1, p2);
            
            ////custName="李四" and custPhone="1390000000"
            Predicate p3 = criteriaBuilder.and(p1, p2);
            
            
            return p3;
        }
    });
    System.out.println(customer);
}

运行结果

模糊匹配

种类

模糊匹配有like，>, < ,>=,<=

对应的方法就是like , gt,lt,ge,le

使用步骤

1.从root中获取要操作的属性

2.调用模糊匹配方法，传入两个参数，第一个是path.as(属性的类型.class),第二个是属性值

测试代码

查询客户名包含传智播客，并且ID>=2的用户

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@Test
public void dimQuery(){
    Customer cus = customerDao.findOne(new Specification<Customer>() {
        @Override
        public Predicate toPredicate(Root<Customer> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {

            //判断客户名包含传智播客 使用like方法
            Predicate p1 = criteriaBuilder.like(root.get("custName").as(String.class), "%传智播客%");
            //判断ID>=2 使用ge方法
            Predicate p2 = criteriaBuilder.ge(root.get("custId").as(Long.class), 2L);

            //custName like "%传智播客%" and custId>=2
            return criteriaBuilder.and(p1, p2);
        }
    });
    System.out.println(cus);
}

运行结果

排序

一个排序条件

需求：按照ID降序查询

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/**
 * 根据一个条件排序
 */
@Test
public void orderByTest1(){
    //根据ID降序排序
    Sort sort = new Sort(Sort.Direction.DESC,"custId");
    //查询条件传入null 表示 查询全部
    List<Customer> all = customerDao.findAll(null, sort);

    for (Customer customer : all) {
        System.out.println(customer);
    }
}

运行结果

多个排序条件

按照电话降序排序，如果电话相同按照ID升序排序

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/**
 * 根据多个条件排序
 */
@Test
public void orderByTest2(){
    //设置排序条件
    Sort.Order o1 = new Sort.Order(Sort.Direction.DESC, "custPhone");
    Sort.Order o2 = new Sort.Order(Sort.Direction.ASC, "custId");

    ArrayList orders = new ArrayList();
    //Order对象添加进去的顺序就是排序顺序
    orders.add(o1);
    orders.add(o2);

    Sort sort = new Sort(orders);//把排序条件设置到Sort对象中
    //查询条件传入null 表示 查询全部
    //select * from cst_customer order by cust_Phone desc, cust_Id asc
    List<Customer> all = customerDao.findAll(null, sort);

    for (Customer customer : all) {
        System.out.println(customer);
    }
}

使用CriteriaQuery完成排序

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@Test
public void orderTest3(){
    List<Customer> all = customerDao.findAll(new Specification<Customer>() {
        @Override
        public Predicate toPredicate(Root<Customer> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
            //设置查询条件,可以不写的
            query.where(cb.like(root.get("custName").as(String.class),"%传%"));
            query.orderBy(cb.desc(root.get("custPhone")), cb.asc(root.get("custId")));
            
            return query.getRestriction();
        }
    });

    for (Customer customer : all) {
        System.out.println(customer);
    }
}

运行结果

分页

需求 查询ID=4,5,6的数据

代码

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/**
 * 分页查询
 */
@Test
public void pageTest(){
    //第一个参数表示查询哪页的数据，页码从0开始
    //第二个参数表示要查询几条记录
    PageRequest pageRequest = new PageRequest(1, 3);
    Page<Customer> all = customerDao.findAll(null, pageRequest);

    for (Customer customer : all) {
        System.out.println(customer);
    }
}

运行结果

案例

需求，网页需要一个搜索功能，如果用输入客户名，则可以根据客户名搜索，如果输入电话，则可以根据电话搜索，如果都输入了就根据用户名和电话搜索，问，service层中的方法应该如何实现

代码

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public List<Customer> search(String custName, String custPhone){
    List<Customer> customers = customerDao.findAll(new Specification<Customer>() {
        @Override
        public Predicate toPredicate(Root<Customer> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
            List<Predicate> list = new ArrayList<>();
            
            //拼接客户名
            if(custName!=null && !custName.trim().equals("")){
                Predicate p = criteriaBuilder.like(root.get("custName").as(String.class), "%" + custName + "%");
                list.add(p);
            }

            //拼接电话
            if(custPhone!=null && !custPhone.trim().equals("")){
                Predicate p = criteriaBuilder.like(root.get("custPhone").as(String.class), "%" + custPhone + "%");
                list.add(p);
            }


            //把查询条件用and进行拼接
            Predicate p = criteriaBuilder.and(list.toArray(new Predicate[0]));

            return p;
        }
    });

    return customers;
}

@Test
public void searchTest(){
    List<Customer> customers = search("传", "1");
    for (Customer customer : customers) {
        System.out.println(customer);
    }
}

运行结果

多表查询

一对多和多对一

需求

一个Customer[这里用户表示公司]对应多个联系人

创建表

为了避免和之前的数据产生冲突，在讲多表查询的时候表名和实体类名后面都会加数字进行区分

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DROP TABLE IF EXISTS `cst_customer2`;

CREATE TABLE `cst_customer2` (
  `cust_id` bigint(32) NOT NULL AUTO_INCREMENT COMMENT '客户编号(主键)',
  `cust_name` varchar(32) NOT NULL COMMENT '客户名称(公司名称)',
  `cust_source` varchar(32) DEFAULT NULL COMMENT '客户信息来源',
  `cust_industry` varchar(32) DEFAULT NULL COMMENT '客户所属行业',
  `cust_level` varchar(32) DEFAULT NULL COMMENT '客户级别',
  `cust_address` varchar(128) DEFAULT NULL COMMENT '客户联系地址',
  `cust_phone` varchar(64) DEFAULT NULL COMMENT '客户联系电话',
  PRIMARY KEY (`cust_id`)
) ENGINE=InnoDB AUTO_INCREMENT=117 DEFAULT CHARSET=utf8;


DROP TABLE IF EXISTS `cst_linkman2`;

CREATE TABLE `cst_linkman2` (
  `lkm_id` bigint(32) NOT NULL AUTO_INCREMENT COMMENT '联系人编号(主键)',
  `lkm_name` varchar(16) DEFAULT NULL COMMENT '联系人姓名',
  `lkm_gender` char(1) DEFAULT NULL COMMENT '联系人性别',
  `lkm_phone` varchar(16) DEFAULT NULL COMMENT '联系人办公电话',
  `lkm_mobile` varchar(16) DEFAULT NULL COMMENT '联系人手机',
  `lkm_email` varchar(64) DEFAULT NULL COMMENT '联系人邮箱',
  `lkm_position` varchar(16) DEFAULT NULL COMMENT '联系人职位',
  `lkm_memo` varchar(512) DEFAULT NULL COMMENT '联系人备注',
  `lkm_cust_id` bigint(32) DEFAULT NULL COMMENT '客户id(外键)',
  PRIMARY KEY (`lkm_id`),
  KEY `FK_cst_linkman_lkm_cust_id` (`lkm_cust_id`)
) ENGINE=InnoDB AUTO_INCREMENT=23 DEFAULT CHARSET=utf8;

创建实体类及映射关系

客户

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package cn.itcast.domain;

import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;


@Entity
@Table(name="cst_customer2")
public class Customer2 {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="cust_id")
    private Long custId;
    @Column(name="cust_address")
    private String custAddress;
    @Column(name="cust_industry")
    private String custIndustry;
    @Column(name="cust_level")
    private String custLevel;
    @Column(name="cust_name")
    private String custName;
    @Column(name="cust_phone")
    private String custPhone;
    @Column(name="cust_source")
    private String custSource;



    public Long getCustId() {
        return custId;
    }

    public void setCustId(Long custId) {
        this.custId = custId;
    }

    public String getCustAddress() {
        return custAddress;
    }

    public void setCustAddress(String custAddress) {
        this.custAddress = custAddress;
    }

    public String getCustIndustry() {
        return custIndustry;
    }

    public void setCustIndustry(String custIndustry) {
        this.custIndustry = custIndustry;
    }

    public String getCustLevel() {
        return custLevel;
    }

    public void setCustLevel(String custLevel) {
        this.custLevel = custLevel;
    }

    public String getCustName() {
        return custName;
    }

    public void setCustName(String custName) {
        this.custName = custName;
    }

    public String getCustPhone() {
        return custPhone;
    }

    public void setCustPhone(String custPhone) {
        this.custPhone = custPhone;
    }

    public String getCustSource() {
        return custSource;
    }

    public void setCustSource(String custSource) {
        this.custSource = custSource;
    }

    

    @Override
    public String toString() {
        return "Customer{" +
                "custId=" + custId +
                ", custAddress='" + custAddress + '\'' +
                ", custIndustry='" + custIndustry + '\'' +
                ", custLevel='" + custLevel + '\'' +
                ", custName='" + custName + '\'' +
                ", custPhone='" + custPhone + '\'' +
                ", custSource='" + custSource + '\'' +
                '}';
    }
}

联系人

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package cn.itcast.domain;

import javax.persistence.*;

@Entity
@Table(name = "cst_linkman2")
public class LinkMan2 {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "lkm_id")
    private Long lkmId; //联系人编号(主键)
    @Column(name = "lkm_name")
    private String lkmName;//联系人姓名
    @Column(name = "lkm_gender")
    private String lkmGender;//联系人性别
    @Column(name = "lkm_phone")
    private String lkmPhone;//联系人办公电话
    @Column(name = "lkm_mobile")
    private String lkmMobile;//联系人手机
    @Column(name = "lkm_email")
    private String lkmEmail;//联系人邮箱
    @Column(name = "lkm_position")
    private String lkmPosition;//联系人职位
    @Column(name = "lkm_memo")
    private String lkmMemo;//联系人备注



    public Long getLkmId() {
        return lkmId;
    }

    public void setLkmId(Long lkmId) {
        this.lkmId = lkmId;
    }

    public String getLkmName() {
        return lkmName;
    }

    public void setLkmName(String lkmName) {
        this.lkmName = lkmName;
    }

    public String getLkmGender() {
        return lkmGender;
    }

    public void setLkmGender(String lkmGender) {
        this.lkmGender = lkmGender;
    }

    public String getLkmPhone() {
        return lkmPhone;
    }

    public void setLkmPhone(String lkmPhone) {
        this.lkmPhone = lkmPhone;
    }

    public String getLkmMobile() {
        return lkmMobile;
    }

    public void setLkmMobile(String lkmMobile) {
        this.lkmMobile = lkmMobile;
    }

    public String getLkmEmail() {
        return lkmEmail;
    }

    public void setLkmEmail(String lkmEmail) {
        this.lkmEmail = lkmEmail;
    }

    public String getLkmPosition() {
        return lkmPosition;
    }

    public void setLkmPosition(String lkmPosition) {
        this.lkmPosition = lkmPosition;
    }

    public String getLkmMemo() {
        return lkmMemo;
    }

    public void setLkmMemo(String lkmMemo) {
        this.lkmMemo = lkmMemo;
    }

    @Override
    public String toString() {
        return "LinkMan{" +
                "lkmId=" + lkmId +
                ", lkmName='" + lkmName + '\'' +
                ", lkmGender='" + lkmGender + '\'' +
                ", lkmPhone='" + lkmPhone + '\'' +
                ", lkmMobile='" + lkmMobile + '\'' +
                ", lkmEmail='" + lkmEmail + '\'' +
                ", lkmPosition='" + lkmPosition + '\'' +
                ", lkmMemo='" + lkmMemo + '\'' +
                '}';
    }
}

一对多关系配置及测试

使用一对多的好处：

​ 通过一的一方可以直接获取多的一方

​ 保存一的一方的时候多的一方也会被顺便保存

具体使用方式请查看测试类

1、说明

客户是一的一方

联系人是多的一方

2.在客户实体类（Customer2）中添加集合属性，存储所有的联系人

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private Set<LinkMan2> linkMan2s = new HashSet<>();

public Set<LinkMan2> getLinkMan2s() {
    return linkMan2s;
}

public void setLinkMan2s(Set<LinkMan2> linkMan2s) {
    this.linkMan2s = linkMan2s;
}

3.配置映射关系·

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/**
 * @OneToMany 说明是一对多关系
 *      targetEntity:关联指定的实体类
 * @JoinColumn 配置外键
 *      name 副表的外键
 *      referencedColumnName 主表的主键
 */
@OneToMany(targetEntity = LinkMan2.class)
@JoinColumn(name="lkm_cust_id",referencedColumnName = "cust_id")
private Set<LinkMan2> linkMan2s = new HashSet<>();

public Set<LinkMan2> getLinkMan2s() {
    return linkMan2s;
}

public void setLinkMan2s(Set<LinkMan2> linkMan2s) {
    this.linkMan2s = linkMan2s;
}

4.创建Dao接口

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package cn.itcast.dao;

import cn.itcast.domain.Customer;
import cn.itcast.domain.Customer2;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;

public interface CustomerDao2 extends JpaRepository<Customer2,Long>,JpaSpecificationExecutor<Customer2> {
}
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public interface LinkManDao2 extends JpaRepository<LinkMan2,Long>,JpaSpecificationExecutor<LinkMan2> {
}

5.测试

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package cn.itcast.dao;

import cn.itcast.domain.Customer2;
import cn.itcast.domain.LinkMan2;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.annotation.Rollback;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.transaction.annotation.Transactional;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class One2ManyTest {
    @Autowired
    private CustomerDao2 customerDao2 ;
    @Autowired
    private LinkManDao2 linkManDao2;
    @Test
    @Transactional
    @Rollback(false)
    /**
     * 测试保存
     */
    public void add(){
        LinkMan2 lm1 = new LinkMan2();
        lm1.setLkmEmail("kefuA@foxmail.com");
        lm1.setLkmGender("男");
        lm1.setLkmMobile("110");
        lm1.setLkmName("客服A");

        LinkMan2 lm2 = new LinkMan2();
        lm2.setLkmEmail("kefuB@foxmail.com");
        lm2.setLkmGender("女");
        lm2.setLkmMobile("119");
        lm2.setLkmName("客服B");

        Customer2 customer2 = new Customer2();
        customer2.setCustName("JACK");

        customer2.getLinkMan2s().add(lm1);//通过客户实体类维护和联系人之间的关系
        customer2.getLinkMan2s().add(lm2);//通过客户实体类维护和联系人之间的关系
        customerDao2.save(customer2);//保存客户
        
        
        linkManDao2.save(lm1);//保存联系人
        linkManDao2.save(lm2);//保存联系人
    }
}

运行结果

多对一关系配置及测试

1.说明

客户(Customer2)[主表]是一的一方

联系人(LinkMan2)[副表]是多的一方

我们需要在多的一方中配置关系

2.在LinkMan2中添加属性CUstomer2

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private Customer2 customer2;

public Customer2 getCustomer2() {
	return customer2;
}

public void setCustomer2(Customer2 customer2) {
	this.customer2 = customer2;
}

3.添加映射关系

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/**
	targetEntity 指定要关联的实体类
	@JoinColumn 配置外键 
		name 副表中外键的名字
		referencedColumnName 主表中主键的名字
*/
@ManyToOne(targetEntity = Customer2.class)
@JoinColumn(name="lkm_cust_id",referencedColumnName = "cust_id")
private Customer2 customer2;

public Customer2 getCustomer2() {
	return customer2;
}

public void setCustomer2(Customer2 customer2) {
	this.customer2 = customer2;
}

4.测试

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package cn.itcast.dao;

import cn.itcast.domain.Customer2;
import cn.itcast.domain.LinkMan2;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.annotation.Rollback;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class Many2OneTest {
    @Autowired
    private CustomerDao2 customerDao2;
    @Autowired
    private LinkManDao2 linkManDao2;

    @Test
    public void findAllTest(){
        List<LinkMan2> all = linkManDao2.findAll();
        for (LinkMan2 linkMan2 : all) {
            Customer2 customer2 = linkMan2.getCustomer2();
            System.out.println(customer2);
        }
    }
    @Test
    @Transactional
    @Rollback(false)
    public void addTest(){
        LinkMan2 lm = new LinkMan2();
        lm.setLkmEmail("kefuB@foxmail.com");
        lm.setLkmGender("女");
        lm.setLkmMobile("119");
        lm.setLkmName("客服BBBB");

        Customer2 customer2 = new Customer2();
        customer2.setCustName("JACKBBB");
        lm.setCustomer2(customer2);//设置关系
        customerDao2.save(customer2);
        linkManDao2.save(lm);

    }
}

运行结果

放弃关系维护

为什么要放弃关系维护

在多对一的情况下保存用户和客户只需要2条SQL，都是INSERT

在一对多的情况下保存用户和客户需要3条SQL语句，2条INSERT,1条UPDATE

如果双向一对多的情况下，可能会出现一下情况

问题代码

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package cn.itcast.dao;

import cn.itcast.domain.Customer2;
import cn.itcast.domain.LinkMan2;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.annotation.Rollback;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.transaction.annotation.Transactional;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class ManyToOne2 {
    @Autowired
    private CustomerDao2 customerDao2 ;
    @Autowired
    private LinkManDao2 linkManDao2;

    @Test
    @Transactional
    @Rollback(false)
    public void addTest(){
        LinkMan2 linkMan = new LinkMan2();
        linkMan.setLkmEmail("郝美丽@foxmail.com");
        linkMan.setLkmGender("女");
        linkMan.setLkmMobile("10086");
        linkMan.setLkmName("郝美丽");

        Customer2 customer = new Customer2();
        customer.setCustName("客户");

        //通过联系人维护关系
        linkMan.setCustomer2(customer);
        //通过客户维护关系
        customer.getLinkMan2s().add(linkMan);

        customerDao2.save(customer);
        linkManDao2.save(linkMan);

    }
}

执行结果

问题

上面代码两个实体类都在维护关系，如果由联系人维护只需要执行2条SQL，如果有客户联系只需要执行3条SQL。运行后发现执行了3条SQL，说明是有客户实体类维护关系的，如果可以由联系人实体类维护关系岂不是更好。

解决办法

其中一个实体类放弃关系的维护，最好客户实体类放弃，因为联系人维护关系可以少执行一条SQL语句

修改客户实体类的OneToMany注解,并删除@JoinColumn注解，代码如下

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//mappedBy 关系由另一个实体类维护，值是另一个实体类中属性的名字
@OneToMany(mappedBy = "customer2")
private Set<LinkMan2> linkMan2s = new HashSet<>();

级联操作

概念

操作一个实体类对象的同时会操作另一个实体类。

注意事项

1.级联操作一定明确操作主体

2.明确了操作主体后，需要在操作主体上指明允许级联操作

​ 操作方式：在@OnetToMany、@ManyToOne、@ManyToMany注解中添加属性cascade = CascadeType.ALL

​ cascade 属性说明

​ 定义源实体和关联的目标实体间的级联关系。当对源实体进行操作时，是否对关联的目标实体也做相同的操作。默认没有级联操作。该参数的可选值有：CascadeType.PERSIST（级联新建）CascadeType.REMOVE（级联删除）CascadeType.REFRESH（级联刷新）CascadeType.MERGE（级联更新）CascadeType.ALL（包含以上四项）

级联保存

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@Test
   @Transactional
   @Rollback(false)
   /**
    * 保存一的一方的同时多的一方会自动被添加到数据库
    */
   public void add(){
      LinkMan2 lm1 = new LinkMan2();
       lm1.setLkmEmail("kefuA@foxmail.com");
       lm1.setLkmGender("男");
       lm1.setLkmMobile("110");
       lm1.setLkmName("客服A");

       LinkMan2 lm2 = new LinkMan2();
       lm2.setLkmEmail("kefuB@foxmail.com");
       lm2.setLkmGender("女");
       lm2.setLkmMobile("119");
       lm2.setLkmName("客服B");

       Customer2 customer2 = new Customer2();
       customer2.setCustName("JACK");

       /*
           用于关联联系人的，关联后在保存客户的同时就会顺便保存联系人
        */
       customer2.getLinkMan2s().add(lm1);
       customer2.getLinkMan2s().add(lm2);

       /*
           关联外键的
        */
       lm1.setCustomer2(customer2);
       lm2.setCustomer2(customer2);
       
       //这里直接保存客户实体类就可以，联系人实体类会被自动保存
       customer2Dao.save(customer2);
   }

级联删除

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@Test
@Transactional
@Rollback(false)
public void delete(){
    Customer2 c = customerDao2.findOne(13L);
    //与c用户相关联的联系人也会被删除
    customerDao2.delete(c);

}

多对多

需求

一个用户(User)对应多个角色(Role)

一个角色(Role)可以对应多个用户(User)

创建表

这里不手动创建了，直接由框架自己生成表

编写实体类及映射关系

用户

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package cn.itcast.domain;

import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

@Entity
@Table(name = "sys_role")
public class Role {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "role_id")
    private Long roleId;
    @Column(name = "role_name")
    private String roleName;



    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;
    }

    
}

角色

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package cn.itcast.domain;

import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

@Entity
@Table(name = "sys_user")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="user_id")
    private Long userId;
    @Column(name="user_name")
    private String userName;
    @Column(name="age")
    private Integer age;



    public Long getUserId() {
        return userId;
    }

    public void setUserId(Long userId) {
        this.userId = userId;
    }

    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;
    }

}

多对多关系配置

1.给用户实体类(User)添加属性及映射关系

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@ManyToMany(targetEntity = Role.class,cascade = CascadeType.ALL)
//JoinTable会生成中间表，表名叫做sys_user_role
@JoinTable(
    	name = "sys_user_role",
        /*
        	joinColumns,配置外键(这里是配置中间表与当前用户表的关系)
        	name:副表(中间表)中的外键的名字
        	referencedColumnName主表(用户表)的主键
        */
        joinColumns = {
            @JoinColumn(name = "sys_user_id",referencedColumnName = "user_id")
        },
        /*
        	inverseJoinColumns,配置另一个表的外键(这里是配置中间与角色表的关系)
        	name:副表(中间表)中的外键的名字
        	referencedColumnName主表(用户表)的主键
        */
        inverseJoinColumns = {
            @JoinColumn(name = "sys_role_id",referencedColumnName = "role_id")
        }
)
private Set<Role> roles = new HashSet<>();
public Set<Role> getRoles() {
    return roles;
}
public void setRoles(Set<Role> roles) {
    this.roles = roles;
}

2.角色(Role)实体类添加属性及映射关系

关系由用户维护就好了，所以在角色实体类中用mapppedBy

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//配置多对多
@ManyToMany(mappedBy = "roles")  //配置多表关系
private Set<User> users = new HashSet<>();
public Set<User> getUsers() {
    return users;
}

public void setUsers(Set<User> users) {
    this.users = users;
}

编写接口

UserDao

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package cn.itcast.dao;

import cn.itcast.domain.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;

public interface UserDao extends JpaRepository<User,Long>,JpaSpecificationExecutor<User> {
}

RoleDao

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package cn.itcast.dao;

import cn.itcast.domain.Role;
import cn.itcast.domain.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;

public interface RoleDao extends JpaRepository<Role,Long> ,JpaSpecificationExecutor<Role> {
}

级联保存

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package cn.itcast.dao;

import cn.itcast.domain.Role;
import cn.itcast.domain.User;
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;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class Many2ManyTest {
    @Autowired
    private UserDao userDao;
    @Autowired
    private RoleDao roleDao;

    @Test
    public void addTest(){
        Role role = new Role();
        role.setRoleName("管理员");

        User user = new User();
        user.setAge(13);
        user.setUserName("老王");

        //配置关系
        user.getRoles().add(role);

        userDao.save(user);

    }
}

运行结果

级联删除

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@Test
public void deleteTest(){
    User user = userDao.findOne(1L);
    userDao.delete(user);

}

运行结果

级联查询(对象导航查询)

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@Test
   public void findTest(){
       User user = userDao.findOne(2L);
       Set<Role> roles = user.getRoles();
       for (Role role : roles) {
           System.out.println(role.getRoleName());
       }
   }

报错

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role:

解决方案1：在User实体类的@ManyToMany注解中添加值fetch

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@ManyToMany(targetEntity = Role.class,cascade = CascadeType.ALL,fetch = FetchType.EAGER)

解决方案2：在junit测试方法findTest()上加@Transactional

一对多关系对象查询总结

通过一的一方查询多的一方默认是延迟查询，因为多的一方可能数据非常多，浪费时间，浪费内存

通过多的一方查询一的一方默认是立即查询，因为一的一方就一条数据，性能可以忽略不计

推荐：使用默认设置，如果使用默认设置，在进行对象查询的时候可能会报org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role:，原因是事务关闭了，我们需要加@Transactional

文章作者: 微信号:hao_yongliang
文章链接: https://haoyongliang.github.io/2019/07/13/SpringBoot/SpringBoot2.X%E9%9B%86%E6%88%90SpringDataJPA(%E4%B8%89)/
版权声明: 本博客所有文章除特别声明外，均采用 CC BY-NC-SA 4.0 许可协议。转载请注明来自 公告：haoyongliang.gitee.io暂停访问！
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