实现线程池的多种方式

大家在研发过程中，难免会遇到使用子线程或者异步线程的场景。它的实现方式有多种，下面就梳理一下。

1、Java原生写法

        继承Thread，或者实现runnable接口；

        不过因为这种方式没有统一的管理方式，到项目后期会看到到处都在创建线程，难以维护。

2、使用JDK自带的线程池 

import java.util.concurrent.ExecutorService; 
import java.util.concurrent.Executors; 
public class MyExecutorUtils { 
    // 定义静态常量，当然可以设置很多属性，这里简单创建了一下
    public static ExecutorService fixedThreadPool = Executors.newFixedThreadPool(5); 
}

public class MyPopRunnableImpl implements Runnable{ 
    public String arg1; 
    public String arg2; 
    public MyPopRunnableImpl() {} 
    public MyPopRunnableImpl(String arg1, String arg2) { 
        this.arg1= arg1; 
        this.arg2= arg2;
    } 

    @Override public void run() { 
        MsgServer.AddPop(arg1, arg2);
    }
}

MyExecutorUtils.fixedThreadPool.execute(new MyPopRunnableImpl(arg1,arg2));

3、使用spring Boot异步线程框架

/**
 * 事件发布器
 */
public static ApplicationEventPublisher publisher;

/**
 * 静态变量通过set方法注入
 * @param publisher\t发布器
 * @author chengmeng
 */
@Autowired
public void setSdkService(ApplicationEventPublisher publisher){
    SqlExecutor.publisher = publisher;
}

//调用
publisher.publishEvent(new AsynWriteToDbEvent(instanceNo));

//配置类
@Configuration 
public class TaskExecutorConfig {
 
    @Bean("bpmTaskExecutor")
    public TaskExecutor bpmTaskExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(1);
        executor.setMaxPoolSize(1);
        executor.setThreadNamePrefix("BpmThread-");
        executor.initialize();
        return executor;
    }
}

//监听器
@Component
public class AsynWriteToDbListener {

    @Async("bpmTaskExecutor")
    @EventListener(AsynWriteToDbEvent.class)
    public void listener(AsynWriteToDbEvent event) {
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            Log.error("线程睡眠1秒钟异常", e);
        }
}

4、使用future工具

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ExecutorService;

public class ExecutorUtils {

    /**
     * 线程池单例
     */
    public static volatile ExecutorService M_TASK =
            ExecutorManageUtils.newFixedThreadPool(300, "LIEMS_M_TASK");

    /**
     * 缓存加载线程池
     */
    public static volatile ExecutorService CACHE_TASK =
            ExecutorManageUtils.newFixedThreadPool(100, "LIEMS_CACHE_TASK");

    /**
     * 获取当前运行中的所有线程池
     * @return  Map<String, ExecutorService> 线程池集合
     */
    public static Map<String, ExecutorService> getAll() {
        final Map<String, ExecutorService> executors = new HashMap<>();

        final Field[] fields = ExecutorUtils.class.getDeclaredFields();
        for (Field field : fields) {
            final int modifiers = field.getModifiers();
            Object value = null;
            try {
                value = field.get(null);
            } catch (IllegalAccessException e) {
                Log.error("获取线程字段值失败", e);
            }

            if (Modifier.isPublic(modifiers) && Modifier.isStatic(modifiers)
                    && value instanceof ExecutorService) {
                executors.put(field.getName(), (ExecutorService) value);
            }
        }
        return executors;
    }

    /**
     * 关闭所有线程池
     */
    public static void shutdownAll() {
        final Map<String, ExecutorService> all = getAll();
        all.values().forEach(ExecutorManageUtils::shutdown);
    }

}

/**
 * 执行缓存加载任务，并且把future增加到list
 * @param service 线程池
 * @param task    task任务
 * @param futures 总任务list
 */
public static void executeTask(ExecutorService service, Runnable task, List<Future<?>> futures) {
        final Future<?> future = service.submit(task);
        futures.add(future);
    }
final List<Future<?>> fus = new ArrayList<>();
// 加载数据库物理表的缓存
executeTask(CACHE_TASK, () -> BeanUtils.getBeanWithNonNull(CommDatabaseTableCached.class).load(), fus);
// 阻塞等待所有加载缓存线程结束
for (Future<?> fu : fus) {
    fu.get();
}