mybatis的作用 Mybatis的三种批量插入方式

1. 循环插入【mybatis的作用 Mybatis的三种批量插入方式】mapper.xml：
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.buhe.demo.mapper.StudentMapper"><insert id="insert" parameterType="Student">INSERT INTO tb_student (name, age, phone, address, class_id) VALUES (#{name},#{age},#{phone},#{address},#{classId})</insert></mapper>mapper接口：
public interface StudentMapper {int insert(Student student);}测试代码：
@SpringBootTestclass DemoApplicationTests { @Resource private StudentMapper studentMapper; @Test public void testInsert(){//数据生成List<Student> studentList = createData(100);//循环插入long start = System.currentTimeMillis();studentList.stream().forEach(student -> studentMapper.insert(student));System.out.println(System.currentTimeMillis() - start); } private List<Student> createData(int size){List<Student> studentList = new ArrayList<>();Student student;for(int i = 0; i < size; i++){student = new Student();student.setName("小王" + i);student.setAge(18);student.setClassId(1);student.setPhone("1585xxxx669");student.setAddress("未知");studentList.add(student);}return studentList; }}2. foreach标签mapper.xml：
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.buhe.demo.mapper.StudentMapper"><insert id="insert" parameterType="Student">INSERT INTO tb_student (name, age, phone, address, class_id) VALUES (#{name},#{age},#{phone},#{address},#{classId})</insert><insert id="insertBatch">INSERT INTO tb_student (name, age, phone, address, class_id) VALUES<foreach collection="list" separator="," item="item">(#{item.name},#{item.age},#{item.phone},#{item.address},#{item.classId})</foreach></insert></mapper>mapper接口：
public interface StudentMapper {int insert(Student student);int insertBatch(List<Student> studentList);}测试代码：
@SpringBootTestclass DemoApplicationTests { @Resource private StudentMapper studentMapper; @Test public void testInsertByForeachTag(){//数据生成List<Student> studentList = createData(100);//使用foreach标签，拼接SQL插入long start = System.currentTimeMillis();studentMapper.insertBatch(studentList);System.out.println(System.currentTimeMillis() - start); } private List<Student> createData(int size){List<Student> studentList = new ArrayList<>();Student student;for(int i = 0; i < size; i++){student = new Student();student.setName("小王" + i);student.setAge(18);student.setClassId(1);student.setPhone("1585xxxx669");student.setAddress("未知");studentList.add(student);}return studentList; }}3. 批处理测试代码：
@SpringBootTestclass DemoApplicationTests { @Autowired private SqlSessionFactory sqlSessionFactory; @Test public void testInsertBatch(){//数据生成List<Student> studentList = createData(100);//使用批处理long start = System.currentTimeMillis();SqlSession sqlSession = sqlSessionFactory.openSession(ExecutorType.BATCH,false);StudentMapper studentMapperNew = sqlSession.getMapper(StudentMapper.class);studentList.stream().forEach(student -> studentMapperNew.insert(student));sqlSession.commit();sqlSession.clearCache();System.out.println(System.currentTimeMillis() - start); } private List<Student> createData(int size){List<Student> studentList = new ArrayList<>();Student student;for(int i = 0; i < size; i++){student = new Student();student.setName("小王" + i);student.setAge(18);student.setClassId(1);student.setPhone("1585xxxx669");student.setAddress("未知");studentList.add(student);}return studentList; }}三种方式的对比MySQL服务器版本：5.6.4
其他依赖版本如下：
<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.4.4</version><relativePath/>  </parent> <groupId>com.buhe</groupId> <artifactId>demo</artifactId> <version>0.0.1-SNAPSHOT</version> <name>demo</name> <description>Demo project for Spring Boot</description> <properties><java.version>1.8</java.version> </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><scope>test</scope></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.41</version></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>1.3.1</version></dependency> </dependencies> <build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins><resources><resource><directory>src/main/java</directory><includes><include>**/*.xml</include></includes></resource></resources> </build></project>三种插入方式在不同数据量下的表现，测试结果：
插入方式10条100条500条1000条循环插入496ms3330ms15584ms33755msforeach标签268ms366ms392ms684ms批处理222ms244ms364ms426ms三种方式中，批处理的方式效率是最高的，尤其是在数据量大的情况下尤为明显。
其次是foreach标签，foreach标签是通过拼接SQL语句的方式完成批量操作的。但是当拼接的SQL过多，导致SQL大小超过了MySQL服务器中max_allowed_packet变量的值时，会导致操作失败，抛出PacketTooBigException异常。
最后是循环插入的方式，这种方式在数据量小的时候可以使用，在数据量大的情况下效率要低很多。