1, Pom.xml file dependencies
<?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-×××tance"
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.xiaohang.springio</groupId>
<artifactId>spring-data-jpa</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-parent</artifactId>
<version>2.1.0.RELEASE</version>
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.7</maven.compiler.source>
<maven.compiler.target>1.7</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-rest</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.1.10</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<!--<scope>runtime</scope>-->
<version>5.1.46</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.16.18</version>
</dependency>
<!-- querydsl -->
<dependency>
<groupId>com.querydsl</groupId>
<artifactId>querydsl-jpa</artifactId>
</dependency>
<dependency>
<groupId>com.querydsl</groupId>
<artifactId>querydsl-apt</artifactId>
<scope>provided</scope>
</dependency>
</dependencies>
<build>
<plug×××>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>springloaded</artifactId>
<version>1.2.5.RELEASE</version>
</dependency>
</dependencies>
</plugin>
<!-- 自动生成query type查询实体 -->
<plugin>
<groupId>com.mysema.maven</groupId>
<artifactId>apt-maven-plugin</artifactId>
<version>1.1.3</version>
<executions>
<execution>
<goals>
<goal>process</goal>
</goals>
<configuration>
<outputDirectory>target/generated-sources/java</outputDirectory>
<processor>com.querydsl.apt.jpa.JPAAnnotationProcessor</processor>
</configuration>
</execution>
</executions>
</plugin>
</plug×××>
</build>
</project>
2, application.yml profile
# 数据库基本配置
spring.datasource.type: com.alibaba.druid.pool.DruidDataSource
spring.datasource.username: root
spring.datasource.password: root
spring.datasource.url: jdbc:mysql://192.168.56.1:3306/test01?useUnicode=true&characterEncoding=UTF-8&useSSL=false
spring.datasource.driver-class-name: com.mysql.jdbc.Driver
# 数据库方言
spring.jpa.properties.hibernate.dialect: org.hibernate.dialect.MySQL57Dialect
spring.jpa.show-sql: true
spring.jpa.hibernate.ddl-auto: update
# 数据库平台
spring.jpa.database-platform: mysql
# JPA配置
spring.jpa.database: mysql
# 禁用视图
spring.jpa.open-in-view: false
3, the entity class
Customer.java
package com.xiaohang.springio.jpastudy.entity;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import javax.persistence.*;
@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity(name = "t_customer")
public class Customer {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column(name = "customer_name")
private String name;
@Column(name = "customer_part")
private String part;
}
Employees.java
package com.xiaohang.springio.jpastudy.entity;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import javax.persistence.*;
@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity(name = "t_employee")
public class Employees {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column(name = "employee_name")
private String name;
@Column(name = "employee_part")
private String part;
}
4、Repository
package com.xiaohang.springio.jpastudy.repository;
import com.xiaohang.springio.jpastudy.entity.Employees;
import org.springframework.data.jpa.repository.JpaRepository;
public interface EmployeesRepository extends JpaRepository<Employees, Long> {
}
package com.xiaohang.springio.jpastudy.repository;
import com.xiaohang.springio.jpastudy.entity.Customer;
import org.springframework.data.jpa.repository.JpaRepository;
public interface CustomerRepository extends JpaRepository<Customer, Long> {
}
5, JPAQueryFactory class with emphasis
package com.xiaohang.springio.jpastudy.service;
import com.querydsl.core.BooleanBuilder;
import com.querydsl.core.QueryResults;
import com.querydsl.core.types.Projections;
import com.querydsl.jpa.JPAExpressions;
import com.querydsl.jpa.impl.JPAQuery;
import com.querydsl.jpa.impl.JPAQueryFactory;
import com.xiaohang.springio.jpastudy.entity.Customer;
import com.xiaohang.springio.jpastudy.entity.Employees;
import com.xiaohang.springio.jpastudy.entity.QCustomer;
import com.xiaohang.springio.jpastudy.entity.QEmployees;
import com.xiaohang.springio.jpastudy.repository.CustomerRepository;
import com.xiaohang.springio.jpastudy.repository.EmployeesRepository;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.context.annotation.Bean;
import org.springframework.test.context.junit4.SpringRunner;
import javax.persistence.EntityManager;
import java.util.List;
@RunWith(SpringRunner.class)
@SpringBootTest
public class BookServiceTest {
// 注入JPAQueryFactory
@Bean
@Autowired
public JPAQueryFactory jpaQuery(EntityManager entityManager) {
return new JPAQueryFactory(entityManager);
}
@Autowired
private JPAQueryFactory jpaQueryFactory;
@Autowired
private EmployeesRepository employeesRepository;
@Autowired
private CustomerRepository customerRepository;
@org.junit.Test
public void jpaQuery() {
Employees employees = new Employees();
employees.setName("老李");
employees.setPart("运营部");
employeesRepository.saveAndFlush(employees);
}
@org.junit.Test
public void updateBook() {
Customer customer = new Customer();
customer.setName("老黄");
customer.setPart("生产部");
customerRepository.saveAndFlush(customer);
}
/**
* 数据库联接查询
*/
@org.junit.Test
public void findAllAuthors() {
QCustomer qc = QCustomer.customer;
QEmployees qe = QEmployees.employees;
// 内联接
List<Employees> employeesList = jpaQueryFactory.select(Projections.constructor(Employees.class, qe.id, qe.name, qe.part)).from(qe).innerJoin(qc).on(qc.id.eq(qe.id)).fetch();
employeesList.forEach(e -> {
System.out.println(e.getName());
});
// 左联接
List<Employees> employeesList1 = jpaQueryFactory.select(Projections.constructor(Employees.class, qe.id, qe.name, qe.part)).from(qe).leftJoin(qc).on(qc.id.eq(qe.id)).fetch();
employeesList1.forEach(employees -> {
System.out.println(employees.getName());
});
// 右联接
List<Employees> employeesList2 = jpaQueryFactory.select(Projections.constructor(Employees.class, qe.id, qe.name, qe.part)).from(qe).rightJoin(qc).on(qc.id.eq(qe.id)).fetch();
employeesList2.forEach(employees -> {
System.out.println(employees.getName());
});
// 左外
List<Employees> employeesList3 = jpaQueryFactory.select(Projections.constructor(Employees.class, qe.id, qe.name, qe.part)).from(qe).leftJoin(qc).on(qc.id.eq(qe.id)).where(qc.id.isNull()).fetch();
employeesList3.forEach(employees -> {
System.out.println(employees.getName());
});
}
/**
* 多条件查询
*/
@org.junit.Test
public void findAll() {
// select customer0_.id as id1_1_, customer0_.customer_name as customer2_1_, customer0_.customer_part as customer3_1_ from t_customer customer0_ where (customer0_.customer_name like ? escape '!' or customer0_.customer_name=?) and (customer0_.id between ? and ?)
QCustomer qc = QCustomer.customer;
BooleanBuilder builder = new BooleanBuilder();
builder.and(qc.name.like('%' + "刘" + '%'));
builder.or(qc.name.eq("老王"));
builder.and(qc.id.between(3, 5));
List<Customer> customerList = jpaQueryFactory.selectFrom(qc).where(builder).fetch();
customerList.forEach(customer -> {
System.out.println(customer.getName());
});
}
/**
* 子查询
*/
@org.junit.Test
public void findAllDto() {
QCustomer qc = QCustomer.customer;
QEmployees qe = QEmployees.employees;
List<Customer> customerList = jpaQueryFactory.selectFrom(qc).where(qc.id.eq(JPAExpressions.select(qe.id).from(qe).where(qe.name.eq("老张")))).fetch();
customerList.forEach(customer -> {
System.out.println(customer.getName());
});
}
/**
* 排序
*/
@Test
public void testDesc() {
QCustomer qc = QCustomer.customer;
List<Customer> customerList = jpaQueryFactory.selectFrom(qc).orderBy(qc.id.desc()).fetch();
customerList.forEach(customer -> {
System.out.println(customer.getName());
});
}
/**
* 分页
*/
@Test
public void testPage() {
QCustomer qc = QCustomer.customer;
QEmployees qe = QEmployees.employees;
// 写法一
JPAQuery<Employees> employeesJPAQuery = jpaQueryFactory.selectFrom(qe);
// offset 起始页
List<Employees> employeesList = employeesJPAQuery.offset(3).limit(2).fetch();
employeesList.forEach(employees -> {
System.out.println(employees);
});
// 写法二
Long total = employeesJPAQuery.fetchCount();
QueryResults<Customer> customerQueryResults = jpaQueryFactory.selectFrom(qc).offset(0).limit(3).fetchResults();
List<Customer> results = customerQueryResults.getResults();
results.forEach(customer -> {
System.out.println(results);
});
}
}