项目场景：

大数据量的List集合，需要把List集合中的数据批量插入数据库中。

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解决方案：

拆分list集合后，然后使用多线程批量插入数据库

1.实体类

package com.test.entity;

import lombok.Data;

@Data
public class TestEntity {
	
	private String id;
	private String name;
}

2.Mapper

如果数据量不大，用foreach标签就足够了。如果数据量很大，建议使用batch模式。

package com.test.mapper;

import java.util.List;

import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Param;

import com.test.entity.TestEntity;

public interface TestMapper {
	
	/**
	  * 1.用于使用batch模式，ExecutorType.BATCH开启批处理模式
	  * 数据量很大，推荐这种方式
	  */
	@Insert("insert into test(id, name) "
			   + " values"
			   + " (#{id,jdbcType=VARCHAR}, #{name,jdbcType=VARCHAR})")
	void testInsert(TestEntity testEntity);
	
	/**
	  * 2.使用foreach标签，批量保存
	  * 数据量少可以使用这种方式
	  */
	@Insert("insert into test(id, name) "
			   + " values"
			   + " <foreach collection='list' item='item' index='index' separator=','>"
			   + " (#{item.id,jdbcType=VARCHAR}, #{item.name,jdbcType=VARCHAR})"
			   + " </foreach>")
	void testBatchInsert(@Param("list") List<TestEntity> list);
}

3.spring容器注入线程池bean对象

package com.test.config;

import java.util.concurrent.Executor;
import java.util.concurrent.ThreadPoolExecutor;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

@Configuration
@EnableAsync
public class ExecutorConfig {
    /**
     * 异步任务自定义线程池
     */
    @Bean(name = "asyncServiceExecutor")
    public Executor asyncServiceExecutor() {
    	ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        //配置核心线程数
        executor.setCorePoolSize(50);
        //配置最大线程数
        executor.setMaxPoolSize(500);
        //配置队列大小
        executor.setQueueCapacity(300);
        //配置线程池中的线程的名称前缀
        executor.setThreadNamePrefix("testExecutor-");
        // rejection-policy：当pool已经达到max size的时候，如何处理新任务
        // CALLER_RUNS：不在新线程中执行任务，而是有调用者所在的线程来执行
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        //调用shutdown()方法时等待所有的任务完成后再关闭
        executor.setWaitForTasksToCompleteOnShutdown(true);
        //等待所有任务完成后的最大等待时间
		executor.setAwaitTerminationSeconds(60);
        return executor;
    }
}

4.创建异步线程业务类

package com.test.service;

import java.util.List;
import java.util.concurrent.CountDownLatch;

import org.apache.ibatis.session.ExecutorType;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Service;

import com.test.entity.TestEntity;
import com.test.mapper.TestMapper;

@Service
public class AsyncService {
	@Autowired
	private SqlSessionFactory sqlSessionFactory;
	
	@Async("asyncServiceExecutor")
    public void executeAsync(List<String> logOutputResults, CountDownLatch countDownLatch) {
        try{
        	//获取session，打开批处理，因为是多线程，所以每个线程都要开启一个事务
        	SqlSession session = sqlSessionFactory.openSession(ExecutorType.BATCH);
        	TestMapper mapper = session.getMapper(TestMapper.class);
        	
            //异步线程要做的事情
        	for (int i = 0; i < logOutputResults.size(); i++) {
    			System.out.println(Thread.currentThread().getName() + "线程：" + logOutputResults.get(i));
    			
    			TestEntity test = new TestEntity();
    			//test.set()
    			//.............
    			//批量保存
    			mapper.testInsert(test);
    			//每1000条提交一次防止内存溢出
    			if(i%1000==0){
    				session.flushStatements();
    			}
			}
        	//提交剩下未处理的事务
    		session.flushStatements();
        }finally {
            countDownLatch.countDown();// 很关键, 无论上面程序是否异常必须执行countDown,否则await无法释放
        }
    }
}

5.拆分list调用异步的业务方法

package com.test.service;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CountDownLatch;

import javax.annotation.Resource;

import org.springframework.stereotype.Service;


@Service
public class TestService {

	@Resource
	private AsyncService asyncService;
	
	public int testMultiThread() {
        List<String> logOutputResults = getTestData();
        //按线程数拆分后的list
        List<List<String>> lists = splitList(logOutputResults);
        CountDownLatch countDownLatch = new CountDownLatch(lists.size());
        for (List<String> listSub:lists) {
            asyncService.executeAsync(listSub, countDownLatch);
        }
        try {
            countDownLatch.await(); //保证之前的所有的线程都执行完成，才会走下面的；
            // 这样就可以在下面拿到所有线程执行完的集合结果
        } catch (Exception e) {
            e.printStackTrace();
        }
        return logOutputResults.size();
    }
	
	public List<String> getTestData() {
		List<String> logOutputResults = new ArrayList<String>();
        for (int i = 0; i < 3000; i++) {
        	logOutputResults.add("测试数据"+i);
		}
        return logOutputResults;
    }
	
	public List<List<String>> splitList(List<String> logOutputResults) {
		List<List<String>> results = new ArrayList<List<String>>();
		
		/*动态线程数方式*/
		// 每500条数据开启一条线程
		int threadSize = 500;
		// 总数据条数
		int dataSize = logOutputResults.size();
		// 线程数，动态生成
		int threadNum = dataSize / threadSize + 1;
	 
	    /*固定线程数方式
		    // 线程数
		    int threadNum = 6;
		    // 总数据条数
		    int dataSize = logOutputResults.size();
		    // 每一条线程处理多少条数据
		    int threadSize = dataSize / (threadNum - 1);
	    */
	 
		// 定义标记,过滤threadNum为整数
		boolean special = dataSize % threadSize == 0;
	 
		List<String> cutList = null;
	 
		// 确定每条线程的数据
		for (int i = 0; i < threadNum; i++) {
			if (i == threadNum - 1) {
				if (special) {
					break;
				}
				cutList = logOutputResults.subList(threadSize * i, dataSize);
			} else {
				cutList = logOutputResults.subList(threadSize * i, threadSize * (i + 1));
			}
			
			results.add(cutList);
		}
		
        return results;
    }
}

5.Controller测试

@RestController
public class TestController {
	
	@Resource
	private TestService testService;
	

	@RequestMapping(value = "/log", method = RequestMethod.GET)
	@ApiOperation(value = "测试")
	public String test() {
		testService.testMultiThread();
		return "success";
	}
}

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总结：

注意这里执行插入的数据是无序的。

Java多线程分段处理List集合_java 每个list分配一个线程-CSDN博客