SpringBoot（七）——教你整合并使用JPA

桃扇骨 2022-02-13 07:15 150阅读 0赞

> 在本篇文章，将手把手带着大家学会使用SpringBoot整合JPA，其实这都很简单。下边就列举出两种整合方法

## 第一种方式 ##

导入如下依赖

<dependency>
                <groupId>org.springframework.data</groupId>
                <artifactId>spring-data-jpa</artifactId>
                <version>1.8.0.RELEASE</version>
            </dependency>
    
            <dependency>
                <groupId>org.hibernate</groupId>
                <artifactId>hibernate-entitymanager</artifactId>
                <version>4.3.6.Final</version>
            </dependency>

编写实体类

import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.Id;
    
    /**
     * 雇员:  先开发实体类===>自动生成数据表
     */
    @Entity
    public class Employee {
    
        private Integer id;
    
        private String name;
    
        private Integer age;
        //主键自增
        @GeneratedValue
        @Id
        public Integer getId() {
            return id;
        }
    
        public void setId(Integer id) {
            this.id = id;
        }
    
        @Column(length = 20)
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public Integer getAge() {
            return age;
        }
    
        public void setAge(Integer age) {
            this.age = age;
        }
    }

编写映射接口，需要注意的是不一定非要@RespositoryDefinition注解，也可以直接继承Repository或者是JapRepository（相比于Repository有分页功能），并且传入实体类和主键的类型。

//可以使用此注解声明实体类，并且在后边指定主键的类型
    @RepositoryDefinition(domainClass = Employee.class, idClass = Integer.class)
    public interface EmployeeRepository { //extends Repository<Employee,Integer>{
        //使用JPA模板——————————————————————————————————————
        public Employee findByName(String name);
    
        // where name like ?% and age <?
        public List<Employee> findByNameStartingWithAndAgeLessThan(String name, Integer age);
    
        // where name like %? and age <?
        public List<Employee> findByNameEndingWithAndAgeLessThan(String name, Integer age);
    
        // where name in (?,?....) or age <?
        public List<Employee> findByNameInOrAgeLessThan(List<String> names, Integer age);
    
        // where name in (?,?....) and age <?
        public List<Employee> findByNameInAndAgeLessThan(List<String> names, Integer age);
    
         //自定义————————————————————————————————————————
        @Query("select o from Employee o where id=(select max(id) from Employee t1)")
        public Employee getEmployeeByMaxId();
    
        @Query("select o from Employee o where o.name=?1 and o.age=?2")
        public List<Employee> queryParams1(String name, Integer age);
    
        @Query("select o from Employee o where o.name=:name and o.age=:age")
        public List<Employee> queryParams2(@Param("name")String name, @Param("age")Integer age);
    
        @Query("select o from Employee o where o.name like %?1%")
        public List<Employee> queryLike1(String name);
    
        @Query("select o from Employee o where o.name like %:name%")
        public List<Employee> queryLike2(@Param("name")String name);
    
        @Query(nativeQuery = true, value = "select count(1) from employee")
        public long getCount();
    
        @Modifying
        @Query("update Employee o set o.age = :age where o.id = :id")
        public void update(@Param("id")Integer id, @Param("age")Integer age);
    
    }

配置文件

spring:  
     jpa:
        hibernate:
    #     更新或者创建数据表结构，如果没有就创建，有的话就更新
          ddl-auto: update
    #    控制台显示SQL
        show-sql: true

在测试类中进行测试（先要给数据库里添加几条记录）

public class EmployeeRepositoryTest {
    
        private ApplicationContext ctx = null;
        private EmployeeRepository employeeRepository = null;
    
         //测试类中的前置通知
        @Before
        public void setup() {
            ctx = new ClassPathXmlApplicationContext("beans-new.xml");
            employeeRepository = ctx.getBean(EmployeeRepository.class);
            System.out.println("setup");
        }
        //测试类中的后置通知
        @After
        public void tearDown() {
            ctx = null;
            System.out.println("Done");
        }
       
        @Test
        public void testFindByName() {
            System.out.println(employeeRepository);
            Employee employee = employeeRepository.findByName("zhangsan");
            System.out.println("id:" + employee.getId()
                    + " , name:" + employee.getName()
                    + " ,age:" + employee.getAge());
        }
    
        @Test
        public void testFindByNameStartingWithAndAgeLessThan() {
            List<Employee> employees = employeeRepository.findByNameStartingWithAndAgeLessThan("test", 22);
    
            for (Employee employee : employees) {
                System.out.println("id:" + employee.getId()
                        + " , name:" + employee.getName()
                        + " ,age:" + employee.getAge());
            }
        }
    
        @Test
        public void testFindByNameEndingWithAndAgeLessThan() {
            List<Employee> employees = employeeRepository.findByNameEndingWithAndAgeLessThan("6", 23);
    
            for (Employee employee : employees) {
                System.out.println("id:" + employee.getId()
                        + " , name:" + employee.getName()
                        + " ,age:" + employee.getAge());
            }
        }
    
    
        @Test
        public void testFindByNameInOrAgeLessThan() {
            List<String> names = new ArrayList<String>();
            names.add("test1");
            names.add("test2");
            names.add("test3");
            List<Employee> employees = employeeRepository.findByNameInOrAgeLessThan(names, 22);
    
            for (Employee employee : employees) {
                System.out.println("id:" + employee.getId()
                        + " , name:" + employee.getName()
                        + " ,age:" + employee.getAge());
            }
        }
    
        @Test
        public void testFindByNameInAndAgeLessThan() {
            List<String> names = new ArrayList<String>();
            names.add("test1");
            names.add("test2");
            names.add("test3");
            List<Employee> employees = employeeRepository.findByNameInAndAgeLessThan(names, 22);
    
            for (Employee employee : employees) {
                System.out.println("id:" + employee.getId()
                        + " , name:" + employee.getName()
                        + " ,age:" + employee.getAge());
            }
        }
    
        @Test
        public void testGetEmployeeByMaxId() {
            Employee employee = employeeRepository.getEmployeeByMaxId();
            System.out.println("id:" + employee.getId()
                    + " , name:" + employee.getName()
                    + " ,age:" + employee.getAge());
        }
    
        @Test
        public void testQueryParams1() {
            List<Employee> employees = employeeRepository.queryParams1("zhangsan", 20);
            for (Employee employee : employees) {
                System.out.println("id:" + employee.getId()
                        + " , name:" + employee.getName()
                        + " ,age:" + employee.getAge());
            }
        }
    
        @Test
        public void testQueryParams2() {
            List<Employee> employees = employeeRepository.queryParams2("zhangsan", 20);
            for (Employee employee : employees) {
                System.out.println("id:" + employee.getId()
                        + " , name:" + employee.getName()
                        + " ,age:" + employee.getAge());
            }
        }
    
    
        @Test
        public void testQueryLike1() {
            List<Employee> employees = employeeRepository.queryLike1("test");
            for (Employee employee : employees) {
                System.out.println("id:" + employee.getId()
                        + " , name:" + employee.getName()
                        + " ,age:" + employee.getAge());
            }
        }
    
        @Test
        public void testQueryLike2() {
            List<Employee> employees = employeeRepository.queryLike2("test1");
            for (Employee employee : employees) {
                System.out.println("id:" + employee.getId()
                        + " , name:" + employee.getName()
                        + " ,age:" + employee.getAge());
            }
        }
    
        @Test
        public void testGetCount() {
            long count = employeeRepository.getCount();
            System.out.println("count:" + count);
        }
    }

> 这就是第一种方法，反正我感觉还是有些麻烦，还有一些繁琐的配置

## 第二种方法 ##

pom依赖

<dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-data-jpa</artifactId>
      </dependency>

编写实体类（也可以使用上边的）

*  Entity:注解这是一个实体类
 *  Id一般和GeneratedValue一起用，Id是表明这是一个主键，GeneratedValue表明这是一个自增键
 *  Column：是属性列可以省略，如果有特殊的属性要求在Column后加上要求
 *  Transient ：声明这是一个非映射字段
 *  Table：一些表信息都基本在Table里，比如Schema，name等  
    还有很多很多，如果有不懂的可以参考下边的博文

[参考][Link 1]

//使用JPA注解配置映射关系
    @Entity //告诉JPA这是一个实体类（和数据表映射的类）
    @Table(name = "tbl_user") //@Table来指定和哪个数据表对应;如果省略默认表名就是user；
    public class User {
    
        @Id //这是一个主键
        @GeneratedValue(strategy = GenerationType.IDENTITY)//自增主键
        private Integer id;
    
        @Column(name = "last_name",length = 50) //这是和数据表对应的一个列
        private String lastName;
        @Column //省略默认列名就是属性名
        private String email;
        
        ......

编写一个映射接口

//继承JpaRepository来完成对数据库的操作，Integer是主键类型
    public interface UserRepository extends JpaRepository<User,Integer> {
    }

配置

> 这样就配置好了一个拥有基本CRUD功能的UserRepository，不仅可以CRUD也可以拼接等，接下来就和上边一样了，直接在测试类测试（需要先注入UserRepository）就ok了！

那个用起来简单就不用多说了！

package com.wrial.demo.dao;
    
    import com.wrial.demo.domain.User;
    import org.junit.Assert;
    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.test.context.junit4.SpringJUnit4ClassRunner;
    
    import java.text.DateFormat;
    import java.util.Date;
    
    @RunWith(SpringJUnit4ClassRunner.class)
    @SpringBootTest
    public class UserRepositoryTest {
    
        @Autowired
        private UserRepository userRepository;
    
        @Test
        public void test() throws Exception {
            Date date = new Date();
            DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG);
            String formattedDate = dateFormat.format(date);
    //
    //        userRepository.save(new User("aa1", "aa@qq.com", "aa", "aa123456",formattedDate));
    //        userRepository.save(new User("bb2", "bb@abc.com", "bb", "bb123456",formattedDate));
    //        userRepository.save(new User("cc3", "cc@1222.com", "cc", "cc123456",formattedDate));
    
            Assert.assertEquals(3, userRepository.findAll().size());
            Assert.assertEquals("bb123456", userRepository.findByUserNameOrEmail("bb2", "cc@11222.com").getNickName());
            userRepository.delete(userRepository.findByUserName("aa1"));
    //        userRepository.deleteAll();
        }
    }

整合和测试的代码已经上传到[GitHub][],感觉不错就点个Star吧！

[Link 1]: https://blog.csdn.net/qq_35873847/article/details/79738667
[GitHub]: https://github.com/wrail/SpringDataJPA/blob/master/src/test/java/com/wrial/demo/dao/UserRepositoryTest.java