mybaits 批量插入，及其测试。

1.引入jar 

<dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>4.3.25.RELEASE</version>
        </dependency>

2.因为是在spring和springmvc，maven下作测试，所以测试类代码必须加入以下注解（重点）若不加入，junit提示空指针异常。

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "classpath:applicationContext.xml" })
public class FirstRun {

    @Autowired
    private SqlSessionTemplate sqlSessionTemplate;
}

3.在spring的配置文件中，配置一个SqlSessionTemplate的类。并且把执行类型，设置为batch

    <bean id="sqlSessionTemplate"
        class="org.mybatis.spring.SqlSessionTemplate"  >
        <constructor-arg name="sqlSessionFactory"
            ref="sqlSessionFactorybean"></constructor-arg>
        <constructor-arg name="executorType" value="BATCH"></constructor-arg>
        
    </bean>

4.测试类，重点，在写测试类时，将测试类，写入到src/main/java/cn/taotao/test/，下，而不是src/test/java下。否则出一堆的找不到资源文件错误。

在java中，自动装载sqlSessionTemplate，然后用它取得sessionFactory，然后打开session并设置不自动提交，得到sqlSession对象。然后用sqlSession对象，获取getmapper，然后做插入测试，之后手动提交。最后关闭session。

在参考的尚硅谷的教学资料视频中，这个地方讲错了。他装载引用的private Sqlsession sqlsession，如果用这样，就没法获得getSqlSessionFactory，进而，没法设置手动提交。

5.java代码如下，4万次插入。单位毫秒。实践表明批处理即使有提升，但是效果不大。

普通版本执行时长66825
批处理执行时长57756
原生态批处理执行时长4543

package cn.taotao.test;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.UUID;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.ExecutorType;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.SqlSessionUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import cn.taotao.bean.Employee;
import cn.taotao.dao.EmployeeMapper;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "classpath:applicationContext.xml" })
public class FirstRun {

    // private SqlSessionTemplate sqlSessionTemplate;

    @Autowired
    private SqlSessionTemplate sqlSessionTemplate;

    @Test
    public void First() throws IOException, SQLException {

        SqlSession sqlSession = sqlSessionTemplate.getSqlSessionFactory().openSession(ExecutorType.BATCH, false);
        long start = System.currentTimeMillis();
        try {

            EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);
            int size = 40000;
            for (int i = 0; i < size; i++) {

                mapper.insert(new Employee(UUID.randomUUID().toString().substring(0, 5), "b", "1", 1));
                 if (i % 1000 == 0 || i == size - 1) {  
                     //手动每1000个一提交，提交后无法回滚  
                     sqlSession.commit();  
                     //清理缓存，防止溢出  
                     sqlSession.clearCache();  }
            }
            
            long end = System.currentTimeMillis();
            System.out.println("批处理执行时长" + (end - start));

        } finally {
            sqlSession.close();
        }
    }

    @Autowired
    private EmployeeMapper empMapper;

    @Test
    public void Second() {

        long start = System.currentTimeMillis();
        for (int i = 0; i < 40000; i++) {
            empMapper.insert(new Employee(UUID.randomUUID().toString().substring(0, 5), "b", "1", 1));
        }
        long end = System.currentTimeMillis();
        System.out.println("普通版本执行时长" + (end - start));
    }

     @Test
    public void Third() throws Exception {

        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession openSession = sqlSessionFactory.openSession(ExecutorType.BATCH, false);

        long start = System.currentTimeMillis();
        try {
            EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class);
            for (int i = 0; i < 40000; i++) {
                mapper.insert(new Employee(UUID.randomUUID().toString().substring(0, 5), "b", "1", 1));
            }

            openSession.commit();
            long end = System.currentTimeMillis();
            // 批量保存执行后的时间
            System.out.println("原生态批处理执行时长" + (end - start));
        } finally {
            openSession.close();
        }
    }
}