如何從applicationContext.xml中的bean讀取值？

Question

我需要在applicationContext.xml中設置參數值接口IP地址

我從屬性文件中讀取了此設置，並以這種方式使用它：

<bean id="hazelcastInterface" class="com.hazelcast.config.InterfacesConfig">
        <property name="interfaces">
            <list>
                <value>${interface.ip_address}</value>
            </list>
        </property>
        <property name="enabled" value="true" />
    </bean>

現在，我需要從命令行參數獲取此值。 我使用Apache Commons CLI解析器，解析參數並從中創建我自己的bean commandLineConf並將其設置為ApplicationContext。

ExternalBeanReferneceFactoryBean.setInstance("commandLineConf", conf);
beanFactory.registerBeanDefinition(
    "commandLineConf",
    BeanDefinitionBuilder.rootBeanDefinition(
        ExternalBeanReferneceFactoryBean.class)
        .getBeanDefinition());

GenericApplicationContext rootAppContext = new GenericApplicationContext(
    beanFactory);
rootAppContext.refresh();

但是我不知道如何從applicationContext.xml中的此bean中獲取價值。 我嘗試了很多方法，例如，但這對我不起作用。

<bean id="hazelcastInterface" class="com.hazelcast.config.InterfacesConfig">
        <property name="interfaces">
            <list>
                <value>#{commandLineConf.ipAddress}</value>
            </list>
        </property>
        <property name="enabled" value="true" />
    </bean>

我究竟做錯了什么？

Answer 1

我使用適當的類測試了您的xml應用程序上下文，並從該主類獲得了預期的ipAddress：

public static void main(String[] args) {

        CommandLineConf conf = new CommandLineConf();
        conf.setIpAddress("127.0.0.1");
        // create root beanFactory
        DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();

        // register bean definition for the command line
        ExternalBeanReferneceFactoryBean.setInstance("commandLineConf", conf);
        beanFactory.registerBeanDefinition(
            "commandLineConf",
            BeanDefinitionBuilder.rootBeanDefinition(
                ExternalBeanReferneceFactoryBean.class)
                .getBeanDefinition());

        GenericApplicationContext rootAppContext = new GenericApplicationContext(
            beanFactory);
        rootAppContext.refresh();

        // create the application context
        ApplicationContext appContext = new ClassPathXmlApplicationContext(new String[] { 
            "/applicationContext.xml"
        }, rootAppContext);

        InterfacesConfig hazelcastInterface = (InterfacesConfig)appContext.getBean("hazelcastInterface");
        System.out.println(hazelcastInterface.getInterfaces().get(0));

    }

因此，您使用的是正確的語法來引用地址，即：＃{commandLineConf.ipAddress}

這使我認為問題出在conf變量中。 您的代碼未顯示其填充方式，我懷疑ipAddress是否丟失。 我不確定，因為您沒有在代碼段中包含解析的參數。 開始構建spring上下文之前，請確保conf變量中存在ipAddress（即，通過打印它）。

我包括了您可能需要具有可用代碼的其余類：

• InterfacesConfig.java

   public class InterfacesConfig { private List<String>interfaces; private boolean enabled; public List<String> getInterfaces() { return interfaces; } public void setInterfaces(List<String> interfaces) { this.interfaces = interfaces; } public boolean isEnabled() { return enabled; } public void setEnabled(boolean enabled) { this.enabled = enabled; } } 

• CommandLineConf.java

   public class CommandLineConf { private String ipAddress; public String getIpAddress() { return ipAddress; } public void setIpAddress(String ipAddress) { this.ipAddress = ipAddress; } } 

• ExternalBeanReferneceFactoryBean.java

   import java.util.HashMap; import java.util.Map; import org.springframework.beans.factory.BeanNameAware; import org.springframework.beans.factory.config.AbstractFactoryBean; public class ExternalBeanReferneceFactoryBean extends AbstractFactoryBean implements BeanNameAware { private static Map<String, Object> instances = new HashMap<String, Object>(); private String beanName; /** * @param instance the instance to set */ public static void setInstance(String beanName, Object instance) { instances.put(beanName, instance); } @Override protected Object createInstance() throws Exception { return instances.get(beanName); } @Override public Class<?> getObjectType() { return instances.get(beanName).getClass(); } @Override public void setBeanName(String name) { this.beanName = name; } } 

• applicationContext.xml中

   <?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: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/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <bean id="hazelcastInterface" class="com.hazelcast.config.InterfacesConfig"> <property name="interfaces"> <list> <value>#{commandLineConf.ipAddress}</value> </list> </property> <property name="enabled" value="true" /> </bean> </beans>