简介:mybatis的批量操作减少数据库连接次数 一、mapper 使用foreach 遍历 批量insert: insert id="addEmpsBatch" INSERT INTO emp(ename,gender,email,did) VALUES foreach collection="emps" item="emp" separator="," (#{emp.e
简介:mybatis的批量操作减少数据库连接次数
一、mapper 使用foreach 遍历
批量insert:
<insert id="addEmpsBatch"> INSERT INTO emp(ename,gender,email,did) VALUES <foreach collection="emps" item="emp" separator=","> (#{emp.eName},#{emp.gender},#{emp.email},#{emp.dept.id}) </foreach> </insert>
批量update:
<update id="updateNewStock" parameterType="java.util.List"> <foreach collection="list" item="bean" index="index" open="" close="" separator=";"> UPDATE green_beans <set> stock=#{bean.stock} </set> <where> beanUid = #{bean.beanUid} </where> </foreach> </update>
二、使用 mybatis ExecutorType.BATCH
使用步骤:
(1)在全局配置文件applcationContext.xml中加入
<!-- 配置一个可以批量执行的sqlSession --> <bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate"> <constructor-arg name="sqlSessionFactory" ref="sqlSessionFactory"></constructor-arg> <constructor-arg name="executorType" value="BATCH"></constructor-arg> </bean>
(2)在service实现中添加:
@Autowired private SqlSession sqlSession; //批量保存员工 @Override public Integer batchEmp() { // TODO Auto-generated method stub //批量保存执行前时间 long start=System.currentTimeMillis(); EmployeeMapper mapper= sqlSession.getMapper(EmployeeMapper.class); for (int i = 0; i < 10000; i++) { mapper.addEmp(new Employee(UUID.randomUUID().toString().substring(0,5),"b","1")); } long end= System.currentTimeMillis(); long time2= end-start; //批量保存执行后的时间 System.out.println("执行时长"+time2); return (int) time2; }
demo:
@Test //批量保存方法测试 public void testBatch() throws IOException{ SqlSessionFactory sqlSessionFactory=getSqlSessionFactory(); //可以执行批量操作的sqlSession SqlSession openSession=sqlSessionFactory.openSession(ExecutorType.BATCH); //批量保存执行前时间 long start=System.currentTimeMillis(); try{ EmployeeMapper mapper= openSession.getMapper(EmployeeMapper.class); for (int i = 0; i < 1000; i++) { mapper.addEmp(new Employee(UUID.randomUUID().toString().substring(0,5),"b","1")); } openSession.commit(); long end= System.currentTimeMillis(); //批量保存执行后的时间 System.out.println("执行时长"+(end-start)); //批量 预编译sql一次==》设置参数==》10000次==》执行1次 677 //非批量 (预编译=设置参数=执行 )==》10000次 1121 }finally{ openSession.close(); } }
mapper:
public interface EmployeeMapper { //批量保存员工 public Long addEmp(Employee employee); }
mapper.xml :
<mapper namespace="com.agesun.mybatis.dao.EmployeeMapper" <!--批量保存员工 --> <insert id="addEmp"> insert into employee(lastName,email,gender) values(#{lastName},#{email},#{gender}) </insert> </mapper>
三、总结:
方式一、需要修改数据库属性添加allowMutiQueries=true,例如:jdbc.url=jdbc:mysql://localhost:3306/mybatis?allowMultiQueries=true
方式二、需要开启事务提交,在applcationContext.xml中添加BATCH
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