spring data jpa入门

spring data jpa对jpa进行了一次完整的封装

JPA是一套规范，内部是有接口和抽象类组成的。hibernate是一套成熟的ORM框架，而且Hibernate实现了JPA规范，所以也可以称hibernate为JPA的一种实现方式，我们使用JPA的API编程，意味着站在更高的角度上看待问题（面向接口编程）Spring Data JPA是Spring提供的一套对JPA操作更加高级的封装，是在JPA规范下的专门用来进行数据持久化的解决方案。

Spring Data JPA 是 Spring 基于 ORM 框架、JPA 规范的基础上封装的一套JPA应用框架，可使开发者用极简的代码即可实现对数据库的访问和操作。它提供了包括增删改查等在内的常用功能，且易于扩展！学习并使用 Spring Data JPA 可以极大提高开发效率！

 

 

 

 

 

<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>

整合Spring Data JPA与Spring

<?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">

    <!--spring和spring-data-jpa的整合-->

    <!--1.创建entityManagerFactory对象交给spring管理-->
    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <!--数据库注入-->
        <property name="dataSource" ref="dataSource"/>
        <!--配置包的扫描-->
        <property name="packagesToScan" value="com.ytkj.entity"/>
        <!--jpa实现厂家-->
        <property name="persistenceProvider">
            <bean class="org.hibernate.jpa.HibernatePersistenceProvider"></bean>
        </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语句-->
                <property name="showSql" value="true" />
            </bean>
        </property>

        <!--jpa方言：高级特性-->
        <property name="jpaDialect">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect" />
        </property>
    </bean>

    <!--2.创建数据连接池-->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <!--数据库信息-->
        <property name="driverClass" value="com.mysql.jdbc.Driver"/>
        <property name="jdbcUrl" value="jdbc:mysql://192.168.2.100:3306/ytkj?serverTimeZone=UTC"/>
        <property name="user" value="root"/>
        <property name="password" value="123456"/>
    </bean>

    <!--3.整合spring-data-jpa-->
    <jpa:repositories base-package="com.ytkj.dao" transaction-manager-ref="transacManager" entity-manager-factory-ref="entityManagerFactory"></jpa:repositories>

    <!--4.配置事务管理器-->
    <bean id="transacManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory" />
    </bean>

    <!--5.声明式事务-->
    <tx:advice id="txAdvice" transaction-manager="transacManager">
        <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>

    <!-- 5.aop-->
    <aop:config>
        <aop:pointcut id="pointcut" expression="execution(* com.ytkj.service.*.*(..))" />
        <aop:advisor advice-ref="txAdvice" pointcut-ref="pointcut" />
    </aop:config>

    <context:component-scan base-package="com.ytkj"></context:component-scan>
</beans>

　　

Spring Data JPA是spring提供的一款对于数据访问层（Dao层）的框架，使用Spring Data JPA，只需要按照框架的规范提供dao接口，不需要实现类就可以完成数据库的增删改查、分页查询等方法的定义，极大的简化了我们的开发过程。

在Spring Data JPA中，对于定义符合规范的Dao层接口，我们只需要遵循以下几点就可以了：

　　1.创建一个Dao层接口，并实现JpaRepository和JpaSpecificationExecutor

 　　2.提供相应的泛型

 

package com.ytkj.entity;

import javax.persistence.*;
import java.io.Serializable;

/**
 *          @Entity
 *         	作用：指定当前类是实体类。
 *         @Table
 *         	作用：指定实体类和表之间的对应关系。
 *         	属性：
 *         		name：指定数据库表的名称
 *         @Id
 *         	作用：指定当前字段是主键。
 *         @GeneratedValue
 *         	作用：指定主键的生成方式。。
 *         	属性：
 *         		strategy ：指定主键生成策略。
 *         @Column
 *         	作用：指定实体类属性和数据库表之间的对应关系
 *         	属性：
 *         		name：指定数据库表的列名称。
 *         		unique：是否唯一
 *         		nullable：是否可以为空
 *         		inserttable：是否可以插入
 *         		updateable：是否可以更新
 *         		columnDefinition: 定义建表时创建此列的DDL
 *         		secondaryTable: 从表名。如果此列不建在主表上（默认建在主表），该属性定义该列所在从表的名字搭建开发环境[重点]
 *
 * 客户实体类
 *      配置映射关系
 *          实体类和表映射
 *          实体类属性和表字段映射
 */
@Entity
@Table(name = "cst_customer")
public class Customer implements Serializable {
    /**
     * 声明主键配置
     */
    @Id
    /**
     * 配置主键的生成策略
     */
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    /**
     * 指定实体类属性和数据库表之间的对应关系
     */
    @Column(name ="cust_id")
    private Long custId;//客户主键
    @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_industry")
    private String custIndustry;//客户行业
    @Column(name ="cust_level")
    private String custLevel;//客户级别
    @Column(name ="cust_address")
    private String custAddress;//客户地址
    @Column(name = "cust_phone")
    private String custPhone;//客户电话

    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 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 getCustAddress() {
        return custAddress;
    }

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

    public String getCustPhone() {
        return custPhone;
    }

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

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

　　

package com.ytkj.dao;

import com.ytkj.entity.Customer;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Repository;

/**
 * JpaRepository<实体类类型，主键类型>：用来完成基本CRUD操作
 * JpaSpecificationExecutor<实体类类型>：用于复杂查询（分页等查询操作）
 */
@Repository
public interface CustomerDao extends JpaRepository<Customer,Long>, JpaSpecificationExecutor<Customer> {
}

import com.ytkj.dao.CustomerDao;
import com.ytkj.entity.Customer;
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 java.util.List;


@RunWith(SpringJUnit4ClassRunner.class)//声明spring提供的单元测试环境
@ContextConfiguration(locations = "classpath:applicationContext.xml")//指定spring容器的配置信息
public class SpringdatajpaTest {
    @Autowired
    CustomerDao customerDao;

    /**
     * 根据id查询
     */
    @Test
    public void findById(){
        Customer customer = customerDao.findOne(1l);
        System.out.println(customer);
    }

    /**
     * 查询所有
     */
    @Test
    public void findAll(){
        List<Customer> list = customerDao.findAll();
        for (Customer customer : list) {
            System.out.println(customer);
        }
    }

    /**
     * save:
     *      保存或者更新
     *      根据传递的对象是否存在主键id.如果没有主键id就是保存
     *                      存在主键id,根据id查询，在跟新数据
     */
    @Test
    public void save(){
        Customer customer=new Customer();
        customer.setCustName("hahahahah");
        customer.setCustPhone("119");
       customerDao.save(customer);//没有id，保存
    }

    @Test
    public void save2(){
        Customer customer=new Customer();
        customer.setCustId(4L);
        customer.setCustName("中国人");
        customer.setCustPhone("0520");
        customer.setCustAddress("曲靖");
        customerDao.save(customer);//有id，更新
    }

    /**
     * 根据id删除
     */
    @Test
    public void deleteById(){
        customerDao.delete(6l);
    }

}