Spring Boot支持Crontab任务改造的方法

package com.github.zhgxun.learn.common.task;import com.github.zhgxun.learn.common.task.annotation.ScheduleTask;import lombok.extern.slf4j.Slf4j;import org.springframework.boot.SpringApplication;import org.springframework.context.ApplicationContext;import org.springframework.context.ApplicationListener;import org.springframework.context.event.ContextRefreshedEvent;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.util.List;import java.util.stream.Collectors;import java.util.stream.Stream;/** * 不自动加入容器, 用于区分是否属于任务启动, 否则放入容器中, Spring 无法选择性执行 * 需要根据特殊参数在启动时注入 * 该监听器本身不能访问容器变量, 如果需要访问, 需要从上下文中获取对象实例后方可继续访问实例信息 * 如果其它类中启动了多线程, 是无法接管异常抛出的, 需要子线程中正确处理退出操作 * 该监听器最好不用直接做线程操作, 子类的实现不干预 */@Slf4jpublic class TaskApplicationListener implements ApplicationListener<ContextRefreshedEvent> {  /**   * 任务启动监听类标识, 启动时注入   * 即是 java -Dspring.task.class=com.github.zhgxun.learn.task.TestTask -jar learn.jar   */  private static final String SPRING_TASK_CLASS = "spring.task.class";  /**   * 支持该注解的方法个数, 目前仅一个   * 可以理解为控制台一次执行一个类, 依赖的任务应该通过其它方式控制依赖   */  private static final int SUPPORT_METHOD_COUNT = 1;  /**   * 保存当前容器运行上下文   */  private ApplicationContext context;  /**   * 监听容器刷新事件   *   * @param event 容器刷新事件   */  @Override  @SuppressWarnings("unchecked")  public void onApplicationEvent(ContextRefreshedEvent event) {    context = event.getApplicationContext();    // 不存在时可能为正常的容器启动运行, 无需关心    String taskClass = System.getProperty(SPRING_TASK_CLASS);    log.info("ScheduleTask spring task Class: {}", taskClass);    if (taskClass != null) {      try {        // 获取类字节码文件        Class clazz = findClass(taskClass);        // 尝试从内容上下文中获取已加载的目标类对象实例, 这个类实例是已经加载到容器内的对象实例, 即可以获取类的信息        Object object = context.getBean(clazz);        Method method = findMethod(object);        log.info("start to run task Class: {}, Method: {}", taskClass, method.getName());        invoke(method, object);      } catch (ClassNotFoundException | IllegalAccessException | InvocationTargetException e) {        e.printStackTrace();      } finally {        // 需要确保容器正常出发停止事件, 否则容器会僵尸卡死        shutdown();      }    }  }  /**   * 根据class路径名称查找类文件   *   * @param clazz 类名称   * @return 类对象   * @throws ClassNotFoundException ClassNotFoundException   */  private Class findClass(String clazz) throws ClassNotFoundException {    return Class.forName(clazz);  }  /**   * 获取目标对象中符合条件的方法   *   * @param object 目标对象实例   * @return 符合条件的方法   */  private Method findMethod(Object object) {    Method[] methods = object.getClass().getDeclaredMethods();    List<Method> schedules = Stream.of(methods)        .filter(method -> method.isAnnotationPresent(ScheduleTask.class))        .collect(Collectors.toList());    if (schedules.size() != SUPPORT_METHOD_COUNT) {      throw new IllegalStateException("only one method should be annotated with @ScheduleTask, but found "          + schedules.size());    }    return schedules.get(0);  }  /**   * 执行目标对象方法   *   * @param method 目标方法   * @param object 目标对象实例   * @throws IllegalAccessException  IllegalAccessException   * @throws InvocationTargetException InvocationTargetException   */  private void invoke(Method method, Object object) throws IllegalAccessException, InvocationTargetException {    method.invoke(object);  }  /**   * 执行完毕退出运行容器, 并将返回值交给执行环节, 比如控制台等   */  private void shutdown() {    log.info("shutdown ...");    System.exit(SpringApplication.exit(context));  }}

package com.github.zhgxun.learn.common.task.annotation;import java.lang.annotation.Documented;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Retention(RetentionPolicy.RUNTIME)@Target(ElementType.METHOD)@Documentedpublic @interface ScheduleTask {}

package com.github.zhgxun.learn.task;import com.github.zhgxun.learn.common.task.annotation.ScheduleTask;import com.github.zhgxun.learn.service.first.LaunchInfoService;import lombok.extern.slf4j.Slf4j;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import java.util.concurrent.TimeUnit;@Service@Slf4jpublic class TestTask {  @Autowired  private LaunchInfoService launchInfoService;  @ScheduleTask  public void test() {    log.info("Start task ...");    log.info("LaunchInfoList: {}", launchInfoService.findAll());    log.info("模拟启动线程操作");    for (int i = 0; i < 5; i++) {      new MyTask(i).start();    }    try {      TimeUnit.SECONDS.sleep(3);    } catch (InterruptedException e) {      e.printStackTrace();    }  }}class MyTask extends Thread {  private int i;  private int j;  private String s;  public MyTask(int i) {    this.i = i;  }  @Override  public void run() {    super.run();    System.out.println("第 " + i + " 个线程启动..." + Thread.currentThread().getName());    if (i == 2) {      throw new RuntimeException("模拟运行时异常");    }    if (i == 3) {      // 除数不为0      int a = i / j;    }    // 未对字符串对象赋值, 获取长度报空指针错误    if (i == 4) {      System.out.println(s.length());    }  }}

package com.github.zhgxun.learn;import com.github.zhgxun.learn.common.task.TaskApplicationListener;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.boot.builder.SpringApplicationBuilder;@SpringBootApplicationpublic class LearnApplication {  public static void main(String[] args) {    SpringApplicationBuilder builder = new SpringApplicationBuilder(LearnApplication.class);    // 根据启动注入参数判断是否为任务动作即可, 否则不干预启动    if (System.getProperty("spring.task.class") != null) {      builder.listeners(new TaskApplicationListener()).run(args);    } else {      builder.run(args);    }  }}

java -Dspring.task.class=com.github.zhgxun.learn.task.TestTask -jar target/learn.jar