作者：楼主楼主
链接：www.jianshu.com/p/cce617be9f9e

1. 反复执行单条插入语句
2. xml拼接sql
3. 批处理执行

代码

<insert id="insertByBatch" parameterType="java.util.List">
    INSERT INTO tb_item VALUES
    <foreach collection="list" item="item" index="index" separator=",">
        (newId(),#{item.uniqueCode},#{item.projectId},#{item.name},#{item.type},#{item.packageUnique},
        #{item.isPackage},#{item.factoryId},#{item.projectName},#{item.spec},#{item.length},#{item.weight},
        #{item.material},#{item.setupPosition},#{item.areaPosition},#{item.bottomHeight},#{item.topHeight},
        #{item.serialNumber},#{item.createTime}</foreach>
</insert>

public interface ItemMapper extends Mapper<Item> {
    int insertByBatch(List<Item> itemList);
}

@Service
public class ItemService {
    @Autowired
    private ItemMapper itemMapper;
    @Autowired
    private SqlSessionFactory sqlSessionFactory;
    //批处理
    @Transactional
    public void add(List<Item> itemList) {
        SqlSession session = sqlSessionFactory.openSession(ExecutorType.BATCH,false);
        ItemMapper mapper = session.getMapper(ItemMapper.class);
        for (int i = ; i < itemList.size(); i++) {
            mapper.insertSelective(itemList.get(i));
            if(i%1000==999){//每1000条提交一次防止内存溢出
                session.commit();
                session.clearCache();
            }
        }
        session.commit();
        session.clearCache();
    }
    //拼接sql
    @Transactional
    public void add1(List<Item> itemList) {
        itemList.insertByBatch(itemMapper::insertSelective);
    }
    //循环插入
    @Transactional
    public void add2(List<Item> itemList) {
        itemList.forEach(itemMapper::insertSelective);
    }
}

@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT, classes = ApplicationBoot.class)
public class ItemServiceTest {
    @Autowired
    ItemService itemService;

    private List<Item> itemList = new ArrayList<>();
    //生成测试List
    @Before 
    public void createList(){
        String json ="{\n" +
                "        \"areaPosition\": \"TEST\",\n" +
                "        \"bottomHeight\": 5,\n" +
                "        \"factoryId\": \"0\",\n" +
                "        \"length\": 233.233,\n" +
                "        \"material\": \"Q345B\",\n" +
                "        \"name\": \"TEST\",\n" +
                "        \"package\": false,\n" +
                "        \"packageUnique\": \"45f8a0ba0bf048839df85f32ebe5bb81\",\n" +
                "        \"projectId\": \"094b5eb5e0384bb1aaa822880a428b6d\",\n" +
                "        \"projectName\": \"项目_TEST1\",\n" +
                "        \"serialNumber\": \"1/2\",\n" +
                "        \"setupPosition\": \"1B柱\",\n" +
                "        \"spec\": \"200X200X200\",\n" +
                "        \"topHeight\": 10,\n" +
                "        \"type\": \"Steel\",\n" +
                "        \"uniqueCode\": \"12344312\",\n" +
                "        \"weight\": 100\n" +
                "    }";
        Item test1 = JSON.parseObject(json,Item.class);
        test1.setCreateTime(new Date());
        for (int i = ; i < 1000; i++) {//测试会修改此数量
            itemList.add(test1);
        }
    }
     //批处理
    @Test
    @Transactional
    public void tesInsert() {
        itemService.add(itemList);
    }
    //拼接字符串
    @Test
    @Transactional
    public void testInsert1(){
        itemService.add1(itemList);
    }
    //循环插入
    @Test
    @Transactional
    public void testInsert2(){
        itemService.add2(itemList);
    }
}

测试结果：

• 循环插入的时间复杂度是 O(n),并且常数C很大
• 拼接SQL插入的时间复杂度（应该）是 O(logn),但是成功完成次数不多，不确定
• 批处理的效率的时间复杂度是 O(logn),并且常数C也比较小

结论

@Transactional
public void add1(List<Item> itemList) {
    itemList.forEach(itemMapper::insertSelective);
}

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