java多线程之CompletionService

1.创建线程task
private final class NamedEntityTask implements Callable<Boolean> {
    private NamedEntity namedEntity;
    private Integer index;
    private Integer pageSize;
    private Integer id;

    public NamedEntityTask(NamedEntity namedEntity,Integer id,Integer index,Integer pageSize){
        this.namedEntity=namedEntity;
        this.id=id;
        this.index=index;
        this.pageSize=pageSize;
    }
    public Boolean call() throws InterruptedException {
　　　　try {
        List<NamedEntityWord> pageDatas = namedEntityWordDao.selectRelaByNamedEntityIdWithPage(id, (index - 1) * pageSize, pageSize);
        for (NamedEntityWord namedEntityWord : pageDatas) {
            namedEntityWord.setId(null);
            namedEntityWord.setNamedEntity(namedEntity);
        }
        namedEntityWordDao.saveNamedEntityWords(pageDatas);
        List<Word> wordList = new ArrayList<>();
        for (NamedEntityWord namedEntityWord : pageDatas) {
            Set<Word> words = namedEntityWord.getWords();
            for (Word w : words) {
                w.setId(null);
                w.setNamedEntityWord(namedEntityWord);
            }
            wordList.addAll(words);
        }
        wordDao.saveWords(wordList);
        log.info(Thread.currentThread().getName() + ":save named_entity........................." + namedEntity.getName() + "..........pageIndex:" + index);
        return true;
    } catch (Exception e) {
        log.error(Thread.currentThread().getName()+"save named_entity failed...................."+namedEntity.getName()+"..........with pageIndex:"+index, e);
    }
    return false;
  }
}
2.创建CompletionService

ExecutorService threadPool = Executors.newFixedThreadPool(4);
CompletionService<Boolean> pool = new ExecutorCompletionService<Boolean>(threadPool);

3.提交task,获取返回值，take()方法阻塞主线程，直到当前子线程执行结束，返回执行结果

public Map<String, Integer> saveEntitys(Map<String, Integer> new_agent_map,Map<String, Agent> src_agents) {
    ExecutorService threadPool = Executors.newFixedThreadPool(4);
    CompletionService<Boolean> pool = new ExecutorCompletionService<Boolean>(threadPool);
    Collection<Agent> values = src_agents.values();
    Map<String, Integer> new_named_entity_map = new HashMap<>();
    for (Agent agent : values) {
        Integer agent_id = agent.getId();
        List<NamedEntity> namedEntities = wordDomain.selectNamedEntitysByAgentId(agent_id);

        for (NamedEntity namedEntity : namedEntities) {
            Integer id = namedEntity.getId();
            namedEntity.setId(null);
            Integer new_agent_id = new_agent_map.get(agent.getName());
            namedEntity.setAgent_id(new_agent_id);
            namedEntityDao.saveNamedEntity(namedEntity);
            new_named_entity_map.put(namedEntity.getName(), namedEntity.getId());
            final int pageSize = 200;

            //计算总页数
            int totalRecords = namedEntityWordDao.selectCountByNamedEntityId(id);
            int totalPages = totalRecords / pageSize;
            if (totalRecords % pageSize != 0) {
                totalPages++;
            }
            for(int i=1;i<=totalPages;i++){
                pool.submit(new NamedEntityTask(namedEntity,id,i,pageSize));
            }

            for(int i=1;i<=totalPages;i++){
                try {
                    Boolean result = pool.take().get();
                    if(result)
                    log.info("save named_entity success............................."+namedEntity.getName()+"......with page index:"+i);
                    else
                        log.info("save named_entity failed............................."+namedEntity.getName()+"......with page index:"+i);
                } catch (Exception e) {
                   log.error(e.getMessage(),e);
                }
            }
        }
    }
    threadPool.shutdown();
    return new_named_entity_map;
}