Spring Data Jpa基础以及基本查询

ゝ一纸荒年。 2024-04-17 18:29 78阅读 0赞

### 1、简介 ###

Spring Data Jpa是spring基于orm、Jpa规范的基础上的封装的一套JPA应用框架，可使开发者用及其简单的代码即可实现对数据库的操作，提高开发效率。

### 2、搭建环境 ###

#### 导入坐标 ####

<?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>com.jpa</groupId>
        <artifactId>SpringDataJpa</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>
    
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.12</version>
                <scope>test</scope>
            </dependency>
    
            <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.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>
    
            <dependency>
                <groupId>c3p0</groupId>
                <artifactId>c3p0</artifactId>
                <version>${c3p0.version}</version>
            </dependency>
    
            <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>
    
            <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>${spring.version}</version>
            </dependency>
    
            <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>
    
    </project>

#### 配置配置文件 ####

<?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: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" xmlns:aop="http://www.springframework.org/schema/aop" 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">
    
    
        <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
            <property name="dataSource" ref="dataSource"/>
    
            <property name="packagesToScan" value="com.jpa.entity"/>
    
            <property name="persistenceProvider">
                <bean class="org.hibernate.jpa.HibernatePersistenceProvider"></bean>
            </property>
    
            <property name="jpaVendorAdapter">
                <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
    
                    <property name="generateDdl" value="false"></property>
    
                    <property name="database" value="MYSQL"></property>
    
                    <property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect"></property>
    
                    <property name="showSql" value="true"></property>
                </bean>
            </property>
    
    
            <property name="jpaDialect">
                <bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect"></bean>
            </property>
        </bean>
    
        <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
            <property name="user" value="root"></property>
            <property name="password" value="111111"></property>
            <property name="jdbcUrl" value="jdbc:mysql:///jpa"></property>
            <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
        </bean>
    
        <jpa:repositories base-package="com.jpa.dao" transaction-manager-ref="transactionManager" entity-manager-factory-ref="entityManagerFactory"></jpa:repositories>
    
        <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
            <property name="entityManagerFactory" ref="entityManagerFactory"></property>
        </bean>
           
    
    
    
    
    
    
    
    
    
    
    
                                                           
    
    
    
    
        <context:component-scan base-package="com.jpa"></context:component-scan>
    </beans>

#### 编写实体类 ####

省略get和set方法

@Entity
    @Table(name = "t_customer")
    public class Customer { 
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "cust_id")
        private int id;
        @Column(name = "cust_address")
        private String address;
        @Column(name = "cust_industry")
        private String industry;
        @Column(name = "cust_level")
        private String level;
        @Column(name = "cust_name")
        private String name;
        @Column(name = "cust_phone")
        private String phone;
        @Column(name = "cust_phone")
        private String source;

#### 编写springdatajpa的dao层接口 ####

*  1、需要继承两个接口：JpaRepository、JpaSpecification。
 *  2、需要提供响应的泛型  
    JpaRepository<T,ID>：其中T是指操作的实体类型，ID表示实体类中的主键属性，封装了基本的crud操作  
    JpaSpecification：T指的是操作的实体类型，封装了复杂操作，例如分页操作

package com.jpa.dao;
    import com.jpa.entity.Customer;
    import com.sun.xml.internal.bind.v2.model.core.ID;
    import org.springframework.data.jpa.repository.JpaRepository;
    import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
    public interface CustomerDao extends JpaRepository<Customer, Long>, JpaSpecificationExecutor<Customer> { 
    }

### 3、增删改查 ###

#### 查询 ####

按id查询

@RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration(locations = "classpath:applicationContext.xml")
    public class daoTest { 
        @Autowired
        private CustomerDao customerDao;
    
        @Test
        public void testFindOne(){ 
            Customer customer = customerDao.findOne(2l);
            System.out.println(customer);
        }
    }

#### 添加和更新 ####

保存或者更新，根据对象是否存在主键，如果有主键就更新，没有就保存。

@Test
    public void testSave(){ 
        Customer customer = new Customer();
        customer.setName("aaa");
        customerDao.save(customer);
    }

更新

@Test
    public void testSave(){ 
       Customer customer = customerDao.findOne(2l);
       customer.setName("bb");
       customerDao.save(customer);
    }

#### 删除 ####

根据id删除

@Test
    public void testDelete(){ 
        customerDao.delete(2l);
    }

#### 查询所有 ####

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

### 4、内部执行过程总结 ###

以findOne为例子  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDU4ODQ5NQ_size_16_color_FFFFFF_t_70]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDU4ODQ5NQ_size_16_color_FFFFFF_t_70]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/17/e15f69e6023f478e99f5fa152194c35b.png