java - Spring @Autowired 注解在 Java TimerTask 中不起作用

Question

如何更改我的代码以使其正常工作？

public class GetDataFromTheWarehouse implements ServletContextListener {

    @Autowired
    ScheduledTask scheduledTask;

    private ScheduledExecutorService scheduler = null;

    public GetDataFromTheWarehouse() {
    }

    public void contextDestroyed(ServletContextEvent arg0) {
        try {
            System.out.println("Scheduler Shutting down successfully " + new Date());
            scheduler.shutdown();
        } catch (Exception ex) {
        }
    }

    public void contextInitialized(ServletContextEvent arg0) {
        if ((scheduler == null) || (!scheduler.isTerminated())) {
            scheduler = Executors.newSingleThreadScheduledExecutor();
            scheduler.scheduleAtFixedRate(scheduledTask, 0, 60*60, TimeUnit.SECONDS);
        }
    }
}

下面是ScheduledTask类，其中productService为空，因此每次调用productService.save()都会失败:

@Component
public class ScheduledTask extends TimerTask {
    @Autowired
    ProductService productService;

    public void run() {
        try {
            parse();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void parse() throws IOException {
            ...
            productService.save(product);
            ...
        }
    }
}

我的applicationContext.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:mvc="http://www.springframework.org/schema/mvc" 
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">

    <!-- Enable autowire -->
    <context:component-scan base-package="com" />
    <context:annotation-config />

    <bean id="usersUpdateTask" class="com.demo.task.ScheduledTask">
    </bean>

    <mvc:annotation-driven /> 

    <mvc:resources mapping="/resources/**" location="/resources/" />

    <mvc:resources mapping="/views/**" location="/views/" />
    <mvc:resources mapping="/img/**" location="/img/" />
    <mvc:resources mapping="/fonts/**" location="/fonts/" />
    <mvc:resources mapping="/css/**" location="/css/" />
    <mvc:resources mapping="/js/**" location="/js/" />

    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver" />
        <property name="url" value="jdbc:mysql://localhost:3306/demo" />
        <property name="username" value="root" />
        <property name="password" value="root" />
    </bean>

    <!-- Session Factory Declaration -->
    <bean id="sessionFactory"
        class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="packagesToScan" value="com.demo.model" />
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
                <prop key="hibernate.show_sql">true</prop>
                <prop key="hibernate.enable_lazy_load_no_trans">true</prop>
                <prop key="hibernate.default_schema">demo</prop>
                <prop key="format_sql">true</prop>
                <prop key="use_sql_comments">true</prop>
                <!-- <prop key="hibernate.hbm2ddl.auto">create</prop> -->
            </props>
        </property>
    </bean>

    <tx:annotation-driven transaction-manager="transactionManager" />

     <bean id="transactionManager"
        class="org.springframework.orm.hibernate4.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactory" />
    </bean>

</beans>

我的演示结构:

Answer 1

当您已经在该 bean 类中使用 @Component 时，为什么还要在 appilcationConfig.xml 中初始化 ScheduledTask。从您的 applicationContext.xml 文件中删除它。

<bean id="usersUpdateTask" class="com.demo.task.ScheduledTask">
</bean>

编辑:添加 Spring Boot 示例。

这是 Spring Boot 中 @Scheduled 和 @Autowired 的示例代码。

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>springboot-scheduler</groupId>
<artifactId>springboot-scheduler-app</artifactId>
<version>1.0.0-SNAPSHOT</version>
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
        <version>1.4.0.RELEASE</version>
    </dependency>
 </dependencies>
</project>

MySpringBootApp.java

package my.spring.app;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableScheduling;

@SpringBootApplication
@EnableScheduling
public class MySpringBootApp {
    public static void main(String[] args) {
    SpringApplication.run(new Object[] { MySpringBootApp.class }, args);
   }
}

MyService.java

package my.spring.app;

import java.text.SimpleDateFormat;
import java.util.Date;
import org.springframework.stereotype.Component;

@Component
public class MyService {    
public String getNextMessage(){
     return new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss").format(new Date());
   }
}

ScheduledTask.java

package my.spring.app;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

@Component
public class ScheduledTask {

@Autowired
MyService service;

@Scheduled(fixedRate = 5000)
public void process() {
    System.out.println("Processing at " + service.getNextMessage());
    }
}

示例输出

Processing at 2016-08-24T14:01:48
Processing at 2016-08-24T14:01:53
Processing at 2016-08-24T14:01:58

希望这有帮助。

EDIT-2:添加 Spring Boot 示例 war 文件版本。使用 Tomcat 8 进行测试。以下两个文件已更改。其他同上。

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>springboot-scheduler</groupId>
<artifactId>springboot-scheduler-app</artifactId>
<version>1.0.0-SNAPSHOT</version>
<packaging>war</packaging>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.4.0.RELEASE</version>
     <relativePath/>
</parent>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-tomcat</artifactId>
        <scope>provided</scope>
    </dependency>
</dependencies>

</project>

MySpringBootApp.java

package my.spring.app;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.support.SpringBootServletInitializer;
import org.springframework.scheduling.annotation.EnableScheduling;

@SpringBootApplication
@EnableScheduling
public class MySpringBootApp extends SpringBootServletInitializer {

@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
    return application.sources(MySpringBootApp.class);
  }

public static void main(String[] args) {

    SpringApplication.run(new Object[] { MySpringBootApp.class }, args);

    }
}