Question

我正在尝试创建一个java.util.concurrent.ThreadPoolExecutor的bean，下面是我在spring配置文件中的内容：

<bean id="threadPoolExector" class="java.util.concurrent.ThreadPoolExecutor" lazy-init="true" scope="singleton">
    <property name="corePoolSize" value="${corePoolSize}"/>
    <property name="maximumPoolSize" value="${maximumPoolSize}"/>
    <property name="keepAliveTime" value="${keepAliveTime}"/>
    <property name="unit" value="java.util.concurrent.TimeUnit.SECONDS"/>
    <property name="workQueue" ref="abcBlockingQueueImpl"></property>
</bean>

<bean id="abcBlockingQueueImpl" class="my.package.AbcBlockingQueueImpl" lazy-init="true" scope="singleton"/>

然后我尝试创建如下：

ThreadPoolExecutor threadPoolExecutor = (ThreadPoolExecutor) applicationContext.getBean("threadPoolExector");

但是我得到了以下异常，我知道ThreadPoolExecutor没有no-arg，但我很惊讶我得到了这个例外。

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'threadPoolExector' defined in ServletContext resource [/WEB-INF/context/web-applicationContext.xml]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [java.util.concurrent.ThreadPoolExecutor]: No default constructor found; nested exception is java.lang.NoSuchMethodException: java.util.concurrent.ThreadPoolExecutor.&lt;init>()

之前我使用过Spring bean，但这看起来像一个奇怪的问题。

Answer 1

问题出在最后：

... No default constructor found; ...

ThreadPoolExecutor没有默认构造函数，您必须模拟代码中描述的内容：使用<constructor-arg>标记而不是<property>标记为至少最小构造函数设置构造函数参数：

ThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue)

在上下文XML文件中：

<bean id="threadPoolExector" class="java.util.concurrent.ThreadPoolExecutor" lazy-init="true" scope="singleton">
    <constructor-arg index="0" type="int" value="${corePoolSize}"/>
    <constructor-arg index="1" type="int" value="${maximumPoolSize}"/>
    <constructor-arg index="2" type="long" value="${keepAliveTime}"/>
    <constructor-arg index="3" type="java.util.concurrent.TimeUnit" value="java.util.concurrent.TimeUnit.SECONDS"/>
    <constructor-arg index="4"  ref="abcBlockingQueueImpl"/>
</bean>

无法使用Spring创建java.util.concurrent.ThreadPoolExecutor的bean

1 个答案: