1.聲明 某個Bean 僅在一定條件下 才初始化Bean,否則 就不初始化。
import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Value; import org.springframework.boot.autoconfigure.condition.ConditionalOnExpression; import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor; import java.util.concurrent.ThreadPoolExecutor; @Configuration public class ThreadPoolConfiguration { @Value("${thread.pool.core.size}") private Integer coreSize; @Value("${thread.pool.max.size}") private Integer maxSize; @Value("${thread.pool.queue.capacity}") private Integer queueCapacity; @Value("${thread.pool.alive.seconds}") private Integer keepAliveSeconds; //聲明線程池1 僅在appCode=swappingA 或者 B的時候，該Bean即該線程池才 初始化 @Bean(name = "myTaskExecutor") @ConditionalOnExpression("'${app.code}'.equals('swappingA') || '${app.code}'.equals('swappingB')") public ThreadPoolTaskExecutor myTaskExecutor() { ThreadPoolTaskExecutor myTaskExecutor = new ThreadPoolTaskExecutor(); myTaskExecutor.setCorePoolSize(coreSize); myTaskExecutor.setMaxPoolSize(maxSize); myTaskExecutor.setQueueCapacity(queueCapacity); myTaskExecutor.setKeepAliveSeconds(keepAliveSeconds); myTaskExecutor.setThreadNamePrefix("my-task-pool-"); return myTaskExecutor; } //聲明線程池2 僅在appCode=swappingC 或者 B的時候，該Bean即該線程池才 初始化 @Bean(name = "myTaskExecutor2") @ConditionalOnExpression("'${app.code}'.equals('swappingC') || '${app.code}'.equals('swappingB')") public ThreadPoolTaskExecutor myTaskExecutor2() { ThreadPoolTaskExecutor myTaskExecutor2 = new ThreadPoolTaskExecutor(); myTaskExecutor2.setCorePoolSize(coreSize); myTaskExecutor2.setMaxPoolSize(maxSize); myTaskExecutor2.setQueueCapacity(queueCapacity); myTaskExecutor2.setKeepAliveSeconds(keepAliveSeconds); myTaskExecutor2.setThreadNamePrefix("my-task2-pool-"); return myTaskExecutor2; } }
2.如上，如果在swappingA應用啟動時，通過@Resource去獲取線程池2，就會啟動失敗，找不到該Bean
@Resource private ThreadPoolTaskExecutor myTaskExecutor2; 或者 @Resource(name = "myTaskExecutor2") private ThreadPoolTaskExecutor myTaskExecutor2;
啟動就會報錯
Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor' available: expected single matching bean but found 1: myTaskExecutor
或者
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'reportTaskExecutor' available
3.所以，想要在swappingA啟動時候，也能取到myTaskExecutor2 該Bean,修改@ConditionalOnExpression的條件
如下標紅新增
@Bean(name = "myTaskExecutor2") @ConditionalOnExpression(" '${app.code}'.equals('swappingA') || '${app.code}'.equals('swappingC') || '${app.code}'.equals('swappingB')") public ThreadPoolTaskExecutor myTaskExecutor2() { ThreadPoolTaskExecutor myTaskExecutor2 = new ThreadPoolTaskExecutor(); myTaskExecutor2.setCorePoolSize(coreSize); myTaskExecutor2.setMaxPoolSize(maxSize); myTaskExecutor2.setQueueCapacity(queueCapacity); myTaskExecutor2.setKeepAliveSeconds(keepAliveSeconds); myTaskExecutor2.setThreadNamePrefix("my-task2-pool-"); return myTaskExecutor2; }