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java_后端: 使用多线程并行查询大批量数据进行导出

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· 阅读 75 · 评论 0 · 4 个月前

应用场景:需要导出大批量数据到excel 表,数据本身的业务处理比较长,所以采用多线程来做

步骤:

1.创建线程池配置;

2.实现callable 接口,因为需要执行数据进行返回,

3,将线程放入队列里执行,并存储返回的数据,

4.获取返回数据,移除线程任务

代码如下:

1.====================================================================

@Configuration
public class ThreadPoolConfiguration {
@Bean
public ThreadPoolTaskExecutor commonThreadPoolTaskExecutor() {
ThreadPoolTaskExecutor pool = new org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor();
int processNum = Runtime.getRuntime().availableProcessors(); // 返回可用处理器的Java虚拟机的数量
int corePoolSize = (int) (processNum / (1 - 0.2));
int maxPoolSize = (int) (processNum / (1 - 0.5));
pool.setCorePoolSize(corePoolSize); // 核心池大小
pool.setMaxPoolSize(maxPoolSize); // 最大线程数
pool.setQueueCapacity(maxPoolSize * 1000); // 队列程度
pool.setThreadPriority(Thread.MAX_PRIORITY);
pool.setDaemon(false);
pool.setKeepAliveSeconds(300);// 线程空闲时间
return pool;
}

}

2.====================================================================
public class OrderExcelHandller  implements Callable<List<OrderExcel>> {
private OrderAppService appService;
private CmsOrderExcelMapper orderExcelMapper;

private List<OrderExcel> list=new CopyOnWriteArrayList();

public OrderExcelHandller() {

}

public OrderExcelHandller(List<OrderExcel> list) {
this.list=list;
}

@Override
public List<OrderExcel> call() throws Exception {
this.appService= SpringUtil.getBean(OrderAppService.class);
this.orderExcelMapper= SpringUtil.getBean(CmsOrderExcelMapper.class);
业务
}

}
3.4.====================================================================
@Autowired
private ThreadPoolTaskExecutor threadPoolTaskExecutor; // 注入线程池
public List<OrderExcel> selectOrderToExcel(Long regionId) throws InterruptedException, ExecutionException {
// 获取队列
ConcurrentLinkedDeque concurrentLinkedDeque = new ConcurrentLinkedDeque();
List<OrderExcel> res=orderExcelMapper.selectList(regionId);
log.info("【selectOrderToExcel】res.size:{}",res.size());
long l = System.currentTimeMillis();
int size=100;
int clycle=res.size()/size;

int yushu=res.size()%size;
int offset=size;
int start=0;int end=size;
// 执行器
ExecutorCompletionService<List<OrderExcel>> completionService = new ExecutorCompletionService<List<OrderExcel>>(
threadPoolTaskExecutor);
for(int i=0;i<clycle;i++){
List<OrderExcel> subIds = new ArrayList(res.subList(start,end));
OrderExcelHandller orderExcelHandller = new OrderExcelHandller(subIds);
// 提交任务
Future<List<OrderExcel>> submit = completionService.submit(orderExcelHandller);
concurrentLinkedDeque.addFirst(submit);
start=end;
end=start+offset;
}
if(yushu >0 && clycle>0){
List<OrderExcel> subIds = new ArrayList(res.subList(size*clycle,res.size()));
OrderExcelHandller orderExcelHandller = new OrderExcelHandller(subIds);
Future<List<OrderExcel>> submit = completionService.submit(orderExcelHandller);
concurrentLinkedDeque.addFirst(submit);
}
else if(yushu >0 && clycle<=0){
List<OrderExcel> subIds =res;
OrderExcelHandller orderExcelHandller = new OrderExcelHandller(subIds);
Future<List<OrderExcel>> submit = completionService.submit(orderExcelHandller);
concurrentLinkedDeque.addFirst(submit);
}
List<OrderExcel> list = new CopyOnWriteArrayList<>();
while (concurrentLinkedDeque.size()>0){
// 获取返回信息
Future<List<OrderExcel>> first = (Future<List<OrderExcel>>) concurrentLinkedDeque.getFirst();
if(first.isDone()){
list.addAll(first.get());
// 队里移除
concurrentLinkedDeque.removeFirst();
}
}
log.info("【selectOrderToExcel】list.size:{}",list.size());
long l1 = System.currentTimeMillis();
log.info("【selectOrderToExcel】使用时长: 用前:{} 用后:{},耗时:{}",l,l1,l1-l);
return list;
}

4.====================================================================
5.====================================================================
由于项目是前后端分离,输出数据不做赘述
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