JPA--SpringDataJPA的四种查询方式

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本文详细介绍SpringDataJPA的四种查询方式，包括接口方法查询、jpql查询、sql语句查询及方法名称规则查询，并提供示例代码，帮助开发者快速掌握SpringDataJPA的查询技巧。

SpringDataJPA的四种查询方式

借助接口中的定义好的方法完成查询
jpql的查询方式
sql语句的查询
方法名称规则查询

示例

创建Maven工程并导入依赖


<?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>pers.zhang</groupId>
    <artifactId>spirngdata_jpa</artifactId>
    <version>1.0-SNAPSHOT</version>

    <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>


</project>

配置文件：applicationContext.xml

<?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/chapter05" />
        <property name="user" value="root" />
        <property name="password" value="123456" />
    </bean>

    <!-- 2.配置entityManagerFactory -->
    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <!-- 扫描包 -->
        <property name="packagesToScan" value="pers.zhang.entity" />
        <!-- 指定实现厂家 -->
        <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>
        <!-- 高级特性 -->
        <property name="jpaDialect">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect" />
        </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>

    <!-- 整合spring data jpa-->
    <jpa:repositories base-package="pers.zhang.dao"
                      transaction-manager-ref="transactionManager"
                      entity-manager-factory-ref="entityManagerFactory"></jpa:repositories>

    <!-- 4.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>

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

    <context:component-scan base-package="pers.zhang"></context:component-scan>

    <!--组装其它 配置文件-->

</beans>

创建表并准备数据
在这里插入图片描述

实体Customer

package pers.zhang.entity;

/**
 * @author zhang
 * @date 2019/12/15 - 22:10
 */

import javax.persistence.*;

/**
 *  1.实体类和表的映射关系
 *      @Entity
 *      @Table
 *  2.类中属性和表中字段的映射关系
 *      @Id
 *      @GeneratedValue
 *      @Colum
 */

@Entity //声明实体类
@Table(name="cst_customer") //建立实体类和表的映射关系
public class Customer {

    @Id//声明当前私有属性为主键
    @GeneratedValue(strategy= GenerationType.IDENTITY) //配置主键的生成策略
    @Column(name="cust_id") //指定和表中cust_id字段的映射关系
    private Long custId;

    @Column(name="cust_name") //指定和表中cust_name字段的映射关系
    private String custName;

    @Column(name="cust_source")//指定和表中cust_source字段的映射关系
    private String custSource;

    @Column(name="cust_industry")//指定和表中cust_industry字段的映射关系
    private String custIndustry;

    @Column(name="cust_level")//指定和表中cust_level字段的映射关系
    private String custLevel;

    @Column(name="cust_address")//指定和表中cust_address字段的映射关系
    private String custAddress;

    @Column(name="cust_phone")//指定和表中cust_phone字段的映射关系
    private String custPhone;

    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 + '\'' +
                '}';
    }
}

Dao层接口：

package pers.zhang.dao;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.jpa.repository.Modifying;
import org.springframework.data.jpa.repository.Query;
import org.springframework.transaction.annotation.Transactional;
import pers.zhang.entity.Customer;

import java.util.List;

/**
 * @author zhang
 * @date 2019/12/15 - 22:22
 */


/**
 * 符合SpringDataJpa的dao层接口规范
 *      JpaRepository<操作的实体类类型， 实体类中主键属性的类型>
 *          封装了基本CRUD操作
 *      JpaSpecificationExecutor<操作的实体类类型>
 *          封装了复杂查询（分页）
 */
public interface CustomerDao extends JpaRepository<Customer, Long>, JpaSpecificationExecutor<Customer> {

    /*
        二：Jpql的查询方式：
            jpql：jpa query Language
            特点：语法或关键字和sql语句类似，查询的是类和类中的属性

            需要将JPQL语句配置到借口的方法上
             1.特有的查询：需要在dao接口上配置方法
             2.在新添加的方法上，使用注解的形式配置Jpql查询语句
             3.注解：@Query
     */

    /*
        根据名称查询客户:使用Jpql查询
            from Customer where custName=?
     */
    @Query(value = "from Customer where custName = ?1")
    public Customer findJpql(String custName);

    /*
        根据客户名称和id查询客户：使用Jpql查询
            from Customer where custName = ?1 and custId = ?2
     */
    @Query(value = "from Customer where custName = ?1 and custId = ?2")
    public Customer findCustNameAndId(String custName, Long custId);

    /*
        根据id更新客户：使用Jpql查询
            使用@Modifying声明此方法是用于更新操作
            调用时使用@Transactional添加事务
     */
    @Query(value = "update Customer set custName = ?1 where custId = ?2")
    @Modifying
    public void updateById(String custName, Long custId);



    /*
        三：sql语句的查询：
            1. 特有的查询：需要在dao接口上配置方法
            2.在新添加的方法上，使用注解的形式配置sql查询语句
            3.注解：@Query
                value：jpql语句 | sql语句
                nativeQuery：false | true ：是否使用本地查询
     */


    /*
        查询所有：使用sql的形式查询
            sql: select * from cst_customer;
     */
    @Query(value = "select * from cst_customer", nativeQuery = true)
    public List<Object[]> findALL();


    /*
        根据名称模糊查询:sql
            sql： select * from cst_customer where cust_name like ?
     */
    @Query(value = "select * from cst_customer where cust_name like ?1", nativeQuery = true)
    public List<Object[]> findListByName(String name);


    /*
        四：方法名称规则查询
            是对Jpql查询更加深入的一层封装
            只需要按照SpringDataJpa提供的方法名称规则定义方法，不需要再去配置Jpql语句，完成查询

           约定：
                findBy：查询
                对象中的属性名（首字母大写）：查询的条件
                     1.根据属性名称进行完整匹配：  findBy + 属性名称
                     2.模糊查询：  findBy + 属性名称 + "查询方式（Like | isnull）"
                     3.多条件查询：   findBy + 属性名称 + “查询方式” + “多条件的连接符（and | or）” + "属性名称" + “查询方式”


                例如：根据姓名查询客户    findByCustName
                     根据姓名模糊查询    findByCustNameLike
                     根据姓名模糊查询和所属行业精准查询   findByCustNameLikeAndCustIndustry
                在SpringDataJpa的运行阶段，会根据方法名称进行解析  findBy     from  xxx(实体类)
                                                                  属性名称  where custName =

     */

    public Customer findByCustName(String name);

    public List<Customer> findByCustNameLike(String name);

    public Customer findByCustNameLikeAndCustIndustry(String name, String industry);
}

借助接口中的定义好的方法完成查询
测试类：

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class mytest {

    @Autowired
    private CustomerDao customerDao;


    /*
        根据id查询
     */
    @Test
    public void testFindById(){
        Customer one = customerDao.findOne(2l);
        System.out.println(one);
    }

    /*
        save:保存或更新
            如果传递的对象中没有id：保存
            如果传递的对象中有id：根据id查询，然后更新数据
     */
    @Test
    public void testSave(){
        Customer customer = new Customer();
        customer.setCustName("三星");
        customer.setCustAddress("思密达");
        customerDao.save(customer);
    }


    /*
        delete:根据id删除
     */
    @Test
    public void testDelete(){
        customerDao.delete(7l);
    }


    /*
        findAll：查询所有
     */
    @Test
    public void testFindAll(){
        List<Customer> all = customerDao.findAll();
        for(Customer c : all)
            System.out.println(c);
    }
    
    /*
        count：统计查询
     */
    @Test
    public void testCount(){
        long count = customerDao.count();
        System.out.println(count);
    }


    /*
        exists：判断主键为？的是否存在
     */
    @Test
    public void testExists(){
        boolean exists = customerDao.exists(4L);
        System.out.println(exists);
    }



    /*
        getOne:根据id从数据库查询
            @Transactional：保证getOne正常运行
        与findOne的区别：
            findOne:底层调用find()方法，立即加载
            getOne：底层调用getReference()方法，延迟加载
     */
    @Test
    @Transactional
    public void testGetOne(){
        Customer one = customerDao.getOne(3L);
        System.out.println(one);
    }
}

jpql的查询方式
测试类：

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class JpqlTest {

    @Autowired
    private CustomerDao customerDao;


    @Test
    public void testFindByName(){
        Customer cusomer = customerDao.findJpql("万达");
        System.out.println(cusomer);

    }


    @Test
    public void testFindByNameAndId(){
        Customer customer = customerDao.findCustNameAndId("万达", 3L);
        System.out.println(customer);
    }


    /*
        测试Jpql的更新操作
            springDataJpa中使用Jpql完成更新或删除操作
                *需要手动添加事务的支持
                *默认会在执行结束之后，回滚事务
                    使用@Rollback取消自动回滚
     */
    @Test
    @Transactional//更新和删除需要添加事务支持
    @Rollback(value = false)
    public void testUpdateNameById(){
        customerDao.updateById("万达万达", 3L);
    }

    
}

sql语句的查询
必须返回List<Object[]>

	@Test
    public void testFindAllBySql(){
        List<Object[]> all = customerDao.findALL();
        for(Object[] objects : all){
            System.out.println(Arrays.toString(objects));
        }
    }

    @Test
    public void testFindListByName(){
        List<Object[]> list = customerDao.findListByName("%万%");
        for(Object[] objects : list){
            System.out.println(Arrays.toString(objects));
        }
    }

方法名称规则查询

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class SimpleTest {
    //测试根据方法命名规则查询
    @Autowired
    private CustomerDao customerDao;

    @Test
    public void testFindByCustName(){
        Customer customer = customerDao.findByCustName("网易");
        System.out.println(customer);
    }
    
    
    @Test
    public void testFindByCustNameLike(){
        List<Customer> list = customerDao.findByCustNameLike("%易");
        for(Customer c : list)
            System.out.println(c);
    }


    @Test
    public void testFindByCustNameLikeAndCustIndustry(){
        Customer customer = customerDao.findByCustNameLikeAndCustIndustry("网%", "游戏");
        System.out.println(customer);
    }
}