我可以为Spring FileSystemResource使用基于环境变量的位置吗？ [英] Can I use an Environment variable based location for Spring FileSystemResource?

问题描述

我要求将所有属性文件存储在目录中。该目录的位置应存储在系统环境变量中。在我的应用程序上下文中，我将需要访问此环境变量来创建FileSystemResource bean。以下是我通常拥有的示例：

I have a requirement to have all our properties files be stored in a directory. The location of this directory should be stored in a system environment variable. In my application context I will need to access this environment variable to create the FileSystemResource bean. Here is an example of what I would normally have:

<bean id="properties" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="locations">
        <bean class="org.springframework.core.io.FileSystemResource">
            <constructor-arg>
                <value>myprops.properties</value>
            </constructor-arg>
        </bean>
    </property>
</bean>

相反，我需要让它像

<value>${prop_file_location}/myprops.properties</value>

其中prop文件位置是环境变量。有谁知道这样做的简单方法？

Where prop file location is an environment variable. Does anyone know an easy way of doing this?

我使用的是spring 2.5.6和java 1.6

I am using spring 2.5.6 and java 1.6

推荐答案

UPDATE

我们后来升级到Spring 3.0.X，我们可以利用spring表达式语言。我们的方法从三个bean简化为以下代码段：

UPDATE

We later upgraded to Spring 3.0.X and we were able to take advantage of the spring expression language. Our approach simplified from three beans to the following snippet:

<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
  <property name="locations">
    <list>
        <value>classpath:defaults.properties</value>
        <value>file:/a/defined/location/project.properties</value>
        <value>file:${AN_ENV_CONFIGURED_DIR}/project.properties</value>
    </list>
  </property>

  <property name="ignoreResourceNotFound" value="true" />
  <property name="searchSystemEnvironment" value="true" />
  <property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE" />
</bean>

这使我们可以拥有一个开发（第一个默认值）静态知名位置，或部署通过env变量配置的位置。配置器按顺序处理这些（即部署优先于默认值）。

This allowed us to have either a development (the first defaults) statically well known location, or a deployed location configured via env variables. The configurer processes these in order (i.e. the deployed takes precedence over the defaults).

我结束了采用非程序化方法。我使用MethodInvoker来检索环境值。然后我能够将其传递给FileSystemResource。

I ended up going with a non programmatic approach. I used a MethodInvoker to retrieve the environment value. I was able to then pass that into the FileSystemResource.

<bean id="configPath" class="org.springframework.beans.factory.config.MethodInvokingFactoryBean" >
    <property name="targetClass" value="java.lang.String" />
    <property name="staticMethod" value="java.lang.System.getenv" />
    <property name="arguments">
        <list>
            <value>NAME_OF_VARIABLE</value>
        </list>
    </property>
</bean>

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