java线程池实战应用总结

一、线程池的创建方式

方式（一）：通过构造函数ThreadPoolExecutor()方式创建线程池

步骤1：先构建线程池

public class AsyncTaskExecutor {/*** 核心线程数*/private static final int corePoolSize = 10;/*** 最大线程数*/private static final int maxPoolSize = 30;/*** 空闲线程回收时间* 空闲线程是指：当前线程池中超过了核心线程数之后，多余的空闲线程的数量*/private static final int keepAliveTime = 100;/*** 任务队列/阻塞队列*/private static final int blockingQueueSize = 99999;private static final ThreadPoolExecutor executorPool = new ThreadPoolExecutor(corePoolSize,maxPoolSize,keepAliveTime,TimeUnit.MILLISECONDS,new LinkedBlockingQueue<>(blockingQueueSize),new ThreadFactoryBuilder().setNameFormat("AsyncTaskThread" + "-%d").build(),new ThreadPoolExecutor.CallerRunsPolicy());/*** 异步任务执行** @param task*/public static void execute(Runnable task) {executorPool.execute(task);}
}

步骤2：通过实现Runnable接口，创建异步任务

@Slf4j
public class CommonTask implements Runnable {/*** 模块ID*/private Long modelId;/*** 模块名称*/private ModelEnum modelName;/*** 构造方法** @param modelId* @param modelName*/public CommonTask(Long modelId, ModelEnum modelName) {this.modelId = modelId;this.modelName = modelName;}@Overridepublic void run() {log.info("start to process common task!!!");if (modelId.intValue() == ModelEnum.Chinese.getCode()) {String name = ModelEnum.Chinese.getValue();log.info("modelID = {}  modelName = {}", modelId, name);} else {modelName = ModelEnum.forValue(modelId.intValue());log.info("modelID = {}  modelName = {}", modelId, modelName.getValue());}}
}

枚举

public enum ModelEnum {Chinese(1, "语文"),Math(2, "数学"),English(3, "数学");/*** code*/private int code;/*** value*/private String value;/*** 映射结果集*/private static final Map<Integer, ModelEnum> VALUE_MAP;static {VALUE_MAP = new HashMap<>();for (ModelEnum modelEnum : ModelEnum.values()) {VALUE_MAP.put(modelEnum.code, modelEnum);}}ModelEnum(int code, String value) {this.code = code;this.value = value;}public int getCode() {return code;}public String getValue() {return value;}/*** 根据code获取枚举实例** @param code* @return*/public static ModelEnum forValue(int code) {return VALUE_MAP.get(code);}}

步骤3：验证

            //步骤1：创建异步任务CommonTask task = new CommonTask(1L, ModelEnum.Chinese);//步骤2：调用线程池异步执行任务AsyncTaskExecutor.execute(task);log.info("main thread over...");

结果如下：

2024-05-23 14:53:16.096  INFO 20652 --- [           main] com.example.demo.dao.UserDaoTest         : main thread over...
2024-05-23 14:53:16.097  INFO 20652 --- [yncTaskThread-0] com.example.demo.task.CommonTask         : start to process common task!!!
2024-05-23 14:53:16.097  INFO 20652 --- [yncTaskThread-0] com.example.demo.task.CommonTask         : modelID = 1  modelName = 语文

方式（二）：构建ThreadPoolTaskExecutor线程池，将其声明为Bean，可以通过注入bean的方式和在方法上使用@Async(“asyncTaskExecutor”)这种注解方式使用此线程池

@Slf4j
@Configuration
@EnableAsync
public class TaskExecutor {@Value("${async.executor.thread.core_pool_size}")private int corePoolSize;@Value("${async.executor.thread.max_pool_size}")private int maxPoolSize;@Value("${async.executor.thread.queue_capacity}")private int queueCapacity;@Value("${async.executor.thread.name.deal_task}")private String taskNamePrefix;/*** 构建线程池 并将其声明为Bean* 方式1：可以通过注入的方式使用此线程池* 方式2：可以在方法上使用@Async("asyncTaskExecutor")这种注解方式使用此线程池** @return*/@Bean(name = "asyncTaskExecutor")public Executor asyncTaskExecutor() {log.info("start asyncTaskExecutor...");ThreadPoolTaskExecutor threadPoolTaskExecutor = new ThreadPoolTaskExecutor();threadPoolTaskExecutor.setCorePoolSize(corePoolSize);threadPoolTaskExecutor.setMaxPoolSize(maxPoolSize);threadPoolTaskExecutor.setQueueCapacity(queueCapacity);threadPoolTaskExecutor.setThreadNamePrefix(taskNamePrefix);//拒绝策略：当前线程数已经达到最大线程数后，如何处理新任务//CallerRunsPolicy()不在新线程中执行任务，而是返回调用者所在的线程来执行threadPoolTaskExecutor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());threadPoolTaskExecutor.initialize();return threadPoolTaskExecutor;}
}

在application.yml中的配置

async:executor:thread:core_pool_size: 10max_pool_size: 10queue_capacity: 99999name:deal_task: DEAL-TASK-

使用方式1：在方法上使用@Async(“asyncTaskExecutor”)这种注解方式使用此线程池
使用方式2：通过注入的方式使用此线程池

@Slf4j
@Service
public class WorkServiceImpl implements WorkService {@Async("asyncTaskExecutor")public void doAsyncTask() throws InterruptedException {Thread.sleep(1000);log.info("do AsyncTask...");}
}

@Slf4j
@RunWith(SpringRunner.class)
@SpringBootTest
public class UserDaoTest {SqlSession sqlSession;@Resourceprivate WorkService workService;@Resourceprivate Executor asyncTaskExecutor;@Testpublic void test() {try {//方式1：在方法上使用@Async("asyncTaskExecutor")这种注解方式使用此线程池for (int i = 0; i < 5; i++) {workService.doAsyncTask();}log.info("main Thread over...");//方式2：通过注入的方式使用此线程池（方便）asyncTaskExecutor.execute(() -> {log.info("async task is running..");});Thread.sleep(5000);}catch (Exception e) {e.printStackTrace();}}
}