在ServletContextListener 的實現類中 使用Spring @Value 註解的方式讀取配置檔案

我想向ServletContextListener中通過Spring @value 的方法讀取 properties 配置檔案資訊，但是我開始的方法不行

public class MyListener implements ServletContextListener{

    @Value("${username}")
    private String username;

    @Value("${password}")
    private String password;

    /* (non-Javadoc)
     * @see javax.servlet.ServletContextListener#contextInitialized(javax.servlet.ServletContextEvent)
     */
    @Override
    public void contextInitialized(ServletContextEvent event) {
        System.out.println("Initialising listener...");
        System.out.println("username:" + username + "password:" + password);
    }

    @Override
    public void contextDestroyed(ServletContextEvent event) {
    }

   
}
 

web.xml：

<listener>
  <listener-class>MyListener</listener-class>
</listener> 

SpringConfig.xml:

<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="ignoreUnresolvablePlaceholders" value="true"/>
        <property name="locations">
            <list>
                <value>classpath:my.properties</value>
            </list>
        </property>
    </bean>
 

my.properties

username=zjl
password=123

輸出：

Initialising listener...
username：null password: null

實現這一點的正確方法是什麼？

參考stackoverflow

 在應用出加入  

SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this);

如下：

public class MyListener implements ServletContextListener{

    @Value("${username}")
    private String username;

    @Value("${password}")
    private String password;

    /* (non-Javadoc)
     * @see javax.servlet.ServletContextListener#contextInitialized(javax.servlet.ServletContextEvent)
     */
    @Override
    public void contextInitialized(ServletContextEvent event) {
        System.out.println("Initialising listener...");
        // 加入下面的這行程式碼
        SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this);
        System.out.println("username:" + username + "password:" + password);
    }

    @Override
    public void contextDestroyed(ServletContextEvent event) {
    }

   
}
 

在ServletContextListener 的實現類中注入Spring bean 也是同樣的操作

Spring – 將依賴項注入到ServletContextListener中

public class MyServletListener implements ServletContextListener, HttpSessionAttributeListener, HttpSessionListener {
    @Autowired
    private SomeService someService;        
    @Autowired
    private AnotherService anotherService; 

    public void contextInitialized(ServletContextEvent sce) {
        SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this);
    }

    ...
}

參考來自：https://codeday.me/bug/20180205/128995.html

                 https://stackoverflow.com/questions/5511152/dependency-inject-servlet-listener