如何将变量传递到FileSystemResource？

Question

predhme

You came up with a way to read environment variable into a Spring Bean then "was able to then pass that into the FileSystemResource".

Here:

Can I use an Environment variable based location for Spring FileSystemResource?

Could you please explain how you passed the variable to FileSystemResource?

Thanks!

Charlie

Answer 1

You want to use a PropertyPlaceholderConfigurer .

Once you have that set up, you should be able to pull any environment variable with the:

${variableName}

syntax anywhere in your configuration file.

Answer 2

I don't like the idea of having system properties for individual variables like these. Sooner you might turn into hundreds of system properties that might need to be set. Instead as others suggest, have the property file outside of the build and specify the location of the property file as a system property.

Having the properties that change with environment, in a properties file outside of the build (JAR / WAR..) helps a lot in making good builds.

This blog post might help.

Or something similar as below:

Using a property placeholder configurer

<bean id="myConfigPlaceholder" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer" p:location="${my.sys.variable}/fooModule/foo.properties" p:placeholderPrefix="#foo{" p:placeholderSuffix="}" />

Injecting in beans

@Value("#foo{some.key.defined.in.fooPropertiesFile}")
 String myFileSystemResourcePath;

(or)

Using util:properties

<util:properties id="fooProps" location="file:///${my.sys.variable}/fooModule.properties/>

Injecting in beans

@Value("#fooProps[some.key.defined.in.fooPropertiesFile]")
 String myFileSystemResourcePath;

Note: When defining property-placeholder-configurer bean, there are different syntactic variations that are supported. You might choose any. Also instead of injecting with @Value, you can reference the property in the xml file with ${variableName} as dlawrence suggested.

Setting the environment variable

for one project: Setting the envVariable, in this example my.sys.variable can be just done with project-->(right click)-->run as-->run as configurations-->vm arguments and there: -Dmy.sys.variable=file:///D:/myBaseDir

globally as a preference:

If this envProp is to be shared with different projects in eclipse, then you can do

Windows->Preferences->Java->Installed JREs->(select the jre)->edit->default vm arguments->and set it with something like -Dmy.sys.variable=file:///D:/myBaseDir