Defaulting system properties from a config file using maven

Question

I have some system properties I specify from the command line eg

mvn -Djdbc.url=... -Djdbc.user=... -Djdbc.password=... clean install

Instead of explicitly specifying each one from the command line I'd like to have a hardcoded .properties file that defaults these values but I can still override them with the command line as needed.

I know the properties-maven-plugin is one of several ways to read properties from a file, but how do I read properties and have them applied system wide? The properties seem to only work when used inside my pom.xml . If I have some other confg file (example a Hibernate config file), it doesn't seem to work.

Example:

In my pom.xml I have

    <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>properties-maven-plugin</artifactId>
        <version>1.0.0</version>
        <executions>
            <execution>
                <goals>
                    <goal>set-system-properties</goal>
                </goals>
                <configuration>
                    <properties>
                        <!-- 
                            Alternatively this can read properties from a config file too 
                            Hardcoded inline here for example purposes
                        -->
                        <property>
                            <jdbc.url>...</jdbc.url>
                            <jdbc.user>...</jdbc.user>
                            <jdbc.property>...</jdbc.property>
                        </property>
                    </properties>
                </configuration>
            </execution>
        </executions>
    </plugin>

Now I can use the jdbc.* properties anywhere in pom.xml and even override them from the command line as needed.

But in my Hibernate config file I have

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">org.postgresql.Driver</property>
        <property name="dialect">org.hibernate.dialect.PostgreSQL95Dialect</property>

        <property name="connection.url">${jdbc.url}</property>
        ...
        ...
    </session-factory>
</hibernate-configuration>

The jdbc.url and other properties show up as blank/null strings here because the properties I read from file only apply in my pom.xml . However if I specify it from the command line it works here since that applies application-wide.

Is there a good way to read properties and have them applied as they would be from the command line, application-wide?

Thanks!

Answer 1

You are mixing up things; the property you are referring to is inside the properties-maven-plugin , and you are configuring it so it can read the property for file.

But this is not the way to use "shared" properties inside maven, it's just a way to read some value from a file.

For being visible outside pom, you have to specify a property as a "global", in example:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

<groupId>*********</groupId>
<artifactId>******</artifactId>
<packaging>war</packaging>
<version>*****</version>
<name>****</name>

<properties>
    <!-- Hibernate Configuration-->
    <jdbc.url>...</jdbc.url>
    <jdbc.user>...</jdbc.user>
    <jdbc.property>...</jdbc.property>
</properties>

Then, you can use these values into your hibernate conf:

<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">org.postgresql.Driver</property>
        <property name="dialect">org.hibernate.dialect.PostgreSQL95Dialect</property>

        <property name="connection.url">${jdbc.url}</property>
        ...
        ...
    </session-factory>
</hibernate-configuration>

That way of setting global properties into the pom is the only way to let them visible outside of it.

I suggest you to move your hibernate connection info inside your pom, and eventually create more profiles, so you can edit them when building the corrisponding package.