JPA批量操作及性能比对

假设需要批量插入10000条实体数据至数据库。如下是各个操作方法及耗时

环境Spring boot

1、JDBC（JdbcTemplate）

pom.xml

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

Service

@Autowired
    private JdbcTemplate jdbcTemplate;
    public void jdbc(List<String> list){
        int[] updatedCountArray=jdbcTemplate.batchUpdate("INSERT INTO customer (name) VALUES (?);", new BatchPreparedStatementSetter() {
            @Override
            public void setValues(PreparedStatement preparedStatement, int i) throws SQLException {
                preparedStatement.setString(1,list.get(i));
            }
            @Override
            public int getBatchSize() {
                return list.size();
            }
        });
    }

2、网上最常见的JPA----entityManager批量操作方法

Entity

package net.xjdsz.model;
import javax.persistence.*;
/**
 * Created by dingshuo on 2017/6/23.
 */
@Entity
@Table(name = "customer", schema = "test", catalog = "")
public class CustomerEntity {
    private int id;
    private String name;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id", nullable = false)
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    @Basic
    @Column(name = "name", nullable = true, length = 100)
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        CustomerEntity that = (CustomerEntity) o;
        if (id != that.id) return false;
        if (name != null ? !name.equals(that.name) : that.name != null) return false;
        return true;
    }
    @Override
    public int hashCode() {
        int result = id;
        result = 31 * result + (name != null ? name.hashCode() : 0);
        return result;
    }
}

Service

private EntityManager em;
    @PersistenceContext(name = "EntityManagerFactory")
    public void SetEntityManager(EntityManager em) {
        this.em = em;
    }
    @Transactional
    public void saveBatch(List<CustomerEntity> list) {
        for (int i = 0; i < 10000; i++) {
            em.persist(list.get(i));
            if (i % 1000 == 0) {
                em.flush();
                em.clear();
            }
        }
    }

3、Jpa---Repository循环写入

Repository

package net.xjdsz.dao;
import net.xjdsz.model.CustomerEntity;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
/**
 * Created by dingshuo on 2017/6/23.
 */
@Repository
public interface   CustomerRepository extends JpaRepository<CustomerEntity,Integer> {
}

4、Jpa--Repository批量写入

Service

@Transactional
    public void saveBatchJpa(List<CustomerEntity> list) {
        repository.save(list);
    }

实验代码：

用的是Spring boot，所以开了一个RestController去做实验

package net.xjdsz;
import net.xjdsz.dao.CustomerRepository;
import net.xjdsz.dao.TestService;
import net.xjdsz.model.CustomerEntity;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.ArrayList;
import java.util.List;
/**
 * Created by dingshuo on 2017/6/23.
 */
@RestController
public class TestController {
    @Autowired
    TestService service;//测试用的Service类
    @Autowired
    CustomerRepository repository; //实体Repository接口
    @GetMapping(value = "/test")
    public void test(){
        List<String> list=new ArrayList<>();  //给jdbctemplate用的集合
        List<CustomerEntity> customerEntityList=new ArrayList<>();//给jpa用的集合
        for(int i=0;i<10000;i++){
            list.add("学生"+i);
            CustomerEntity customerEntity=new CustomerEntity();
            customerEntity.setName("学生"+i);
            customerEntityList.add(customerEntity);
        }
        //1.jdbc
        long startTime=System.currentTimeMillis();   //获取开始时间
        service.jdbc(list);
        long endTime=System.currentTimeMillis(); //获取结束时间
        System.out.println("jdbc程序运行时间： "+(endTime-startTime)+"ms");
        //2.jpa-em
        long startTime1=System.currentTimeMillis();   //获取开始时间
        service.saveBatch(customerEntityList);
        long endTime1=System.currentTimeMillis(); //获取结束时间
        System.out.println("JPA-EM程序运行时间： "+(endTime1-startTime1)+"ms");
        //3.jpa-循环
        long startTime2=System.currentTimeMillis();   //获取开始时间
        for(int i=0;i<customerEntityList.size();i++){
            repository.save(customerEntityList.get(i));
        }
        long endTime2=System.currentTimeMillis(); //获取结束时间
        System.out.println("JPA-循环程序运行时间： "+(endTime2-startTime2)+"ms");
        //4.jpa-集合
        long startTime3=System.currentTimeMillis();   //获取开始时间
        repository.save(customerEntityList);
        long endTime3=System.currentTimeMillis(); //获取结束时间
        System.out.println("JPA-集合程序运行时间： "+(endTime3-startTime3)+"ms");
    }
}

实验结果

jdbc程序运行时间： 878ms
JPA-EM程序运行时间： 2018ms
JPA-循环程序运行时间： 21915ms
JPA-集合程序运行时间： 2373ms

结论就是如果追求极致的性能（批量操作速度），优选JDBC。EM和JPA直接操作集合没有太大的性能区别，这对于新接触Spring JPA（比如我）的人来说，不比纠结有时候没法注入EM，直接使用JPA操作集合即可。

JPA的循环造作相当于对单条insert重复了10000遍，自然最慢，也不推荐了。

如下是JPA操作集合的代码，可以看出起始内部也是用的em，所以可以放心大胆的用了。

@Transactional
	public <S extends T> List<S> save(Iterable<S> entities) {
		List<S> result = new ArrayList<S>();
		if (entities == null) {
			return result;
		}
		for (S entity : entities) {
			result.add(save(entity));
		}
		return result;
	}
/*
	 * (non-Javadoc)
	 * @see org.springframework.data.repository.CrudRepository#save(java.lang.Object)
	 */
	@Transactional
	public <S extends T> S save(S entity) {
		if (entityInformation.isNew(entity)) {
			em.persist(entity);
			return entity;
		} else {
			return em.merge(entity);
		}
	}

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