PropertyPlaceholderConfigurer not loading programm

问题:

I have a custom ApplicationContext class where I'm trying to programmatically load a PropertyPlaceholderConfigurer, then use the placeholders in my XML config file.

I've tried three different approaches so far, and each time I get an error like this:

org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named '${domain}.testId' is defined

What I am doing wrong?

Context class

public class MyApplicationContext extends GenericApplicationContext {
    public MyApplicationContext (String... locations) throws IOException {

        // method one
        ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(this);
        scanner.scan("com.my.package");

        // method two
        new MyPropertyPlaceholderConfigurer().postProcessBeanFactory(getBeanFactory());

        // method three
        getBeanFactory().registerSingleton("propertyPlaceholderConfigurer", new MyPropertyPlaceholderConfigurer());

        // load XML config files
        XmlBeanDefinitionReader xmlReader = new XmlBeanDefinitionReader(this);
        for (String location : locations) {
            xmlReader.loadBeanDefinitions(location);
        }
    }
}

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:aop="http://www.springframework.org/schema/aop"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <bean id="test.testId" class="java.lang.String">
        <constructor-arg value="this is the test value" />
    </bean>

    <bean id="prod.testId" class="java.lang.String">
        <constructor-arg value="this is the prod value" />
    </bean>

    <alias name="${domain}.testId" alias="testId" />

</beans>

Usage

MyApplicationContext context = new MyApplicationContext(
    new String[] { "test.xml" });
Assert.assertEquals("this is the test value", context.getBean("testId"));

回答1:

I appreciate the answers on how to define the bean, but it turns out the problem was much simpler. I was loading the bean just fine, but I wasn't properly initializing my context after loading all the beans. A simple call to refresh() did the trick.

MyApplicationContext context = new MyApplicationContext(
    new String[] { "test.xml" });

context.refresh();   // this runs BeanFactoryPostProcessors like 
                     // MyPropertyPlaceholderConfigurer, among other things

Assert.assertEquals("this is the test value", context.getBean("testId"));

回答2:

If you just want to use your own custom MyPropertyPlaceholderConfigurer (assuming it extends PropertyPlaceholderConfigurer, then all you need to do is to put it as a bean in your application context, it'll do all the rest for you:

<bean class="my.pkg.MyPropertyPlaceholderConfigurer" />

回答3:

This is standard way how make your properties accessible in configuration file.

<util:list id="locations">
    <value>classpath:appconfig.properties</value>
    <value>classpath:jdbc.properties</value>
</util:list>

<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"
      p:ignoreResourceNotFound="true"
      p:locations-ref="locations" />

<!-- bean that uses properties -->
<bean id="dataSource"
      class="com.mchange.v2.c3p0.ComboPooledDataSource"
      p:driverClass="${jdbc.driver}"
      p:jdbcUrl="${jdbc.url}"
      p:user="${jdbc.user}"
      p:password="${jdbc.pw}"
      p:initialPoolSize="5"
      p:minPoolSize="5"
      p:maxPoolSize="50"
      p:idleConnectionTestPeriod="5" />

Another quite useful way how to "inject" properties in your configuration file on ANY place is using maven: you use same syntax ${property-name} but values are supplied earlier during maven build process - this is relevant part of maven configuration:

<properties>
<jdbc.url>jdbc:mysql://localhost:3306/dummyuserdb</jdbc.url>
<jdbc.user>root</jdbc.user>
<jdbc.pw>admin</jdbc.pw>
</properties> 

and you have to include your spring's configuration directory in maven filtered resources:

<build>
    <resources>
    <resource>
        <directory>${basedir}/src/main/webapp/WEB-INF/spring-config</directory>
        <filtering>true</filtering>
        </resource>
</resources>

Or if you prefer java configuration:

 @Configuration
 @PropertySource(value = "config/jdbc.properties")
 public class BaseWebConfig {

    @Autowired Environment env;

    @Bean
    public MyBean myBean() {
       MyBean myBean = new MyBean();
       String propertyValue = env.getProperty("my-property-name");
       // do something with myBean and propertyValue
       return myBean;
    }
 }

}