Getting started with spring-data-jpa

premise

• Understand the maven project
• Learned the spring basic framework

1. Project configuration

1.1pom.xml file

<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>cn.liuhao</groupId>
	<artifactId>jpa</artifactId>
	<version>0.0.1-SNAPSHOT</version>

	<properties>
		<spring.version>5.2.9.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>
		<java.version>1.8</java.version>
	</properties>


	<dependencies>
		<!-- 单元测试 -->
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.9</version>
			<scope>test</scope>
		</dependency>
		<!-- spring aop -->
		<dependency>
			<groupId>org.aspectj</groupId>
			<artifactId>aspectjweaver</artifactId>
			<version>1.9.6</version>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-aop</artifactId>
			<version>${spring.version}</version>
		</dependency>

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

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

		<!-- spring hibernate -->
		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-core</artifactId>
			<version>${hibernate.version}</version>
		</dependency>
		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-validator</artifactId>
			<version>5.2.1.Final</version>
		</dependency>
		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-entitymanager</artifactId>
			<version>${hibernate.version}</version>
		</dependency>
		<!-- c3p0数据库连接池 -->
		<dependency>
			<groupId>c3p0</groupId>
			<artifactId>c3p0</artifactId>
			<version>${c3p0.version}</version>
		</dependency>
		<!-- 日志相关包 -->
		<dependency>
			<groupId>log4j</groupId>
			<artifactId>log4j</artifactId>
			<version>${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>
		<!-- mysql-connect-j -->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>8.0.21</version>
		</dependency>

		<!-- spring data jpa -->
		<dependency>
			<groupId>org.springframework.data</groupId>
			<artifactId>spring-data-jpa</artifactId>
			<version>2.3.4.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-test</artifactId>
			<version>${spring.version}</version>
		</dependency>
		
		<!-- spring data 要求必须导入以下两个坐标 -->
		<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>
	</dependencies>


	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.8.1</version>
				<configuration>
					<target>1.8</target>
					<source>1.8</source>
				</configuration>
			</plugin>
		</plugins>
	</build>
</project>

1.2jpa configuration file

• The configuration file of jpa must be placed under classpath:, which corresponds to the src/main/resources directory in the maven project
• The name of the jpa configuration file must be: persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
	xmlns="http://java.sun.com/xml/ns/persistence"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/persistence 
               http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
	<!-- 需要配置persistence-unit节点 
		 name：持久化单元名称
		 transaction-type:事务管理的方式，有两种，1.JTA:分布式事务管理，2.RESOURCE_LOCAL:本地事务管理
		 -->
	<persistence-unit name="myJPA" transaction-type="RESOURCE_LOCAL">
		<!-- jpa 实现方式 -->
		<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
		<!-- 配置数据库信息 ，配置jpa实现的配置信息-->
		<properties>
			<!-- 数据库信息  -->
			<property name="javax.persistence.jdbc.user" value="root"/>
			<property name="javax.persistence.jdbc.password" value="lh19990909"/>
			<property name="javax.persistence.jdbc.driver" value="com.mysql.cj.jdbc.Driver"/>
			<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/ssm?usessL=false&amp;serverTimezone=UTc"/>
			<!-- 配置jpa实现的配置信息 -->
			<!-- 显示sql日志，打印到控制台  hibernate.show -->
			<property name="hibernate.show" value="true"/>
			<!-- 自动创建数据库表 hibernate.hbm2ddl.auto
				value: create 程序运行时创建数据库表（如果有表，先册除表再创建)
				value：update 程序运行时创建表（如果有表，不会创建表）
				value：none	  不会创建表
			-->
			<property name="hibernate.hbm2ddl.auto" value="create"/>
		</properties>
	</persistence-unit>
</persistence>