SpringDataJPA
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ORM思想
ORM 即 Object-Relational Mapping,对象关系映射。简单来说就是通过操作对应的实体类来操作表的思想。
实现了ORM思想的框架:hibernate 等
JPA概述
JPA的全称是Java Persistence API, 即Java 持久化API。JPA是一种基于orm思想的规范,是由接口和抽象类组成的;
SpringDataJpa
1.SpringDataJpa与 Jpa 和 hibernate 的关系:
SpringDataJpa只是jpa规范的进一步封装,底层也需要hibernate等框架的实现
2.SpringDataJpa入门:
(1) 引入依赖
<properties> <spring.version>4.2.4.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>4.9</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>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-orm</artifactId> <version>${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> <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>4.2.4.RELEASE</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>
(2) SpringDataJpa与Spring整合的配置文件
<?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"> <!-- 1.dataSource 配置数据库连接池--> <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"> <property name="driverClass" value="com.mysql.jdbc.Driver" /> <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/jpa" /> <property name="user" value="root" /> <property name="password" value="root" /> </bean> <!-- 2.配置entityManagerFactory --> <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="packagesToScan" value="com.myjava.jpa.entity" /> <!--JPA的供应商适配器--> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"> <property name="generateDdl" value="false" /> <property name="database" value="MYSQL" /> <property name="showSql" value="true" /> </bean> </property> </bean> <!-- 3.事务管理器--> <!-- JPA事务管理器 --> <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory" ref="entityManagerFactory" /> </bean> <!--txAdvice--> <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--> <aop:config> <aop:pointcut id="pointcut" expression="execution(* com.myjava.jpa.service.*.*(..))" /> <aop:advisor advice-ref="txAdvice" pointcut-ref="pointcut" /> </aop:config> <!--4.dao包扫描器--> <jpa:repositories base-package="com.myjava.jpa.dao" transaction-manager-ref="transactionManager" entity-manager-factory-ref="entityManagerFactory"></jpa:repositories> </beans>
(3) 编写实体类和数据库表的映射配置
//声明实体类 @Entity //建立实体类和表的映射关系 @Table(name = "cust") public class Customer implements Serializable{ @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "cust_id") private Long id; @Column(name = "cust_name") private String name; @Column(name = "cust_industry") private String industry; @Column(name = "cust_level") private String level; @Column(name = "cust_addressdress") private String addressdress; //标注一对一关联关系 @OneToOne(cascade = CascadeType.ALL) //标注外键关联 //name:标注表中存储外键字段的字段名称 @JoinColumn(name = "ext_Id") //也可以主键关联,但是关联的类里面也要加上这个注解 //@PrimaryKeyJoinColumn private CustomerExt ext; @Override public String toString() { return "Customer{" + "id=" + id + ", name=‘" + name + ‘‘‘ + ", industry=‘" + industry + ‘‘‘ + ", level=‘" + level + ‘‘‘ + ", addressdress=‘" + addressdress + ‘‘‘ + ‘}‘; } public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getIndustry() { return industry; } public void setIndustry(String industry) { this.industry = industry; } public String getLevel() { return level; } public void setLevel(String level) { this.level = level; } public String getAddressdress() { return addressdress; } public void setAddressdress(String addressdress) { this.addressdress = addressdress; } public CustomerExt getExt() { return ext; } public void setExt(CustomerExt ext) { this.ext = ext; } }
(4) 按照框架规范提供dao接口
//泛型右边参数是主键类型 public interface CustomerDao extends JpaRepository<Customer,Long> { }
(5)基本的CURD操作
1.增:save
2.删:delete
3.改:先查出来,然后save
4.查:findOne,findAll,getOne(这个方法是懒加载)
(6)更加灵活的查询方法
基本的查询方法不够灵活时的其他方法(比如不能通过其他属性查询)
①命名规则查询
按照Spring Data JPA 定义的规则,查询方法以findBy开头
②JPQL语句查询
在dao中定义一个方法,加上@Query注解,在注解中输入JPQL语句即可
例如:@Query(value="from Customer")
③原生sql语句
在@Query注解中输入sql语句,加个 nativeQuery = true 即可
3.SpringDataJpa与表关系
(1) 一对一
外键关联
外键保存的表对应的类中应该加@OneToOne注解,@JoinColumn注解
package com.myjava.jpa.entity; import javax.persistence.*; import java.io.Serializable; //声明实体类 @Entity //建立实体类和表的映射关系 @Table(name = "cust") public class Customer implements Serializable{ @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "cust_id") private Long id; @Column(name = "cust_name") private String name; @Column(name = "cust_industry") private String industry; @Column(name = "cust_level") private String level; @Column(name = "cust_addressdress") private String addressdress; //标注一对一关联关系 @OneToOne(cascade = CascadeType.ALL) //标注外键关联 //name:标注表中存储外键字段的字段名称 @JoinColumn(name = "ext_Id") //也可以主键关联,但是关联的类里面也要加上这个注解 //@PrimaryKeyJoinColumn private CustomerExt ext; //get set方法 }
(2) 一对多
一的一方只用加入加入@OneToMany注解,多的一方要加入 @ManyToOne注解 和 @JoinColumn注解
@Entity @Table(name = "master") public class Master { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "master_id") private Long masterId; private String name; private Integer age; private String info; //fetch:默认是延迟加载LAZY @OneToMany(cascade = CascadeType.ALL,mappedBy = "master",fetch = FetchType.EAGER) private Set<Servant> servants = new HashSet<Servant>(); }
@Entity @Table(name = "servant") public class Servant { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "servant_id") private Long servantId; private String name; private String ability; private String profession; @ManyToOne @JoinColumn(name = "mas_id") private Master master;
(3) 多对多
两方都使用@ManyToMany注解,一方要加入@JoinTable标签创建中间表
@JoinTable标签有3个重要的参数
① name:中间表表名
② joinColumn:当前表映射在中间表的列
③ inverseJoinColumns:另一个类的列映射在中间表的名称
@Entity @Table(name = "sys_user") public class User { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "uid") private Long id; private String username; private String password; @ManyToMany(cascade = CascadeType.ALL) @JoinTable( name = "user_role", joinColumns = @JoinColumn(name = "user_id"), inverseJoinColumns = @JoinColumn(name = "role_id") )
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