Maven Filtering Replace Multiple Tokens During Build

Introduction

In this post I will discuss about replacing the multiple tokens in XML file using maven-resources-plugin. Situation may occur where you need to replace some place holders in the XML file during build of your application and need to create a zip file under the target directory, then you may use this example as a reference. Such XML files or zip file may be required for configuring the application or project. I will use here maven-assembly-plugin to build the zip file under target directory.

Prerequisites

Maven 3.6.1 – 3.8.5, Java 8+

Project Setup

Create a maven based standalone project in your favorite IDE or tool with the following details:

Group Id: com.roytuts
Artifact Id: maven-replace-token-xml

Sample XML File

Let’s say, you have the below sample XML file – test.xml under xml folder under the project directory.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<config sharedLib="library">
	<cores adminPath="/admin" hostPort="${jetty.port}"
		hostContext="${hostContext}">
		<core name="activeCustomers" instanceDir="activeCustomers"
			dataDir="[[search.home]]/activeCustomers" />

		<core name="carriers" instanceDir="carriers"
			dataDir="[[search.home]]/carriers" />

		<core name="cities" instanceDir="cities"
			dataDir="[[search.home]]/cities" />

		<core name="customerAddresses" instanceDir="customerAddresses"
			dataDir="[[search.home]]/customerAddresses" />

		<core config="config.xml" name="servicerequest_questions_en"
			instanceDir="servicerequest_questions_en" schema="schema.xml"
			dataDir="[[search.home]]/servicerequest_questions" />
	</cores>
</config>

In the above file, you see there are two types of place holders – ${..} and [[...]].

In your XML file you can have only one or more place holders like these.

So, I will replace those place holders with required values during maven build.

At the same time, I will also copy the XML file after replacement into a new file under target/config directory.

Finally, I will build the zip directory using maven-assembly-plugin.

Creating Assembly Config

I will create an assembly.xml file under the project root directory with the below content.

You may find more on assembly configuration here.

<assembly
	xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2 http://maven.apache.org/xsd/assembly-1.1.2.xsd">
	<id>zip</id>
	<formats>
		<format>zip</format>
	</formats>
	<includeBaseDirectory>false</includeBaseDirectory>
	<fileSets>
		<fileSet>
			<directory>target/config</directory>
			<useDefaultExcludes>true</useDefaultExcludes>
			<outputDirectory>./</outputDirectory>
		</fileSet>
	</fileSets>
</assembly>

Updating Build File – pom.xml

Update the default generated pom.xml file to include the required plugins.

In the below pom.xml file, I have defined properties to be replaced for the place holders in XML file.

This project does not have any other resources so it does not include any dependency.

<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>com.roytuts</groupId>
	<artifactId>maven-replace-token-xml</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>pom</packaging>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<maven.compiler.source>11</maven.compiler.source>
		<maven.compiler.target>11</maven.compiler.target>
		<jetty.port>9988</jetty.port>
		<hostContext>localhost</hostContext>
		<search.home>/web/SearchIndex</search.home>
	</properties>

	<dependencies>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.8.1</version>
			</plugin>
			<plugin>
				<artifactId>maven-resources-plugin</artifactId>
				<version>3.1.0</version>
				<executions>
					<execution>
						<id>copy-resources</id>
						<phase>validate</phase>
						<goals>
							<goal>copy-resources</goal>
						</goals>
						<configuration>
							<outputDirectory>target/config</outputDirectory>
							<resources>
								<resource>
									<directory>xml</directory>
									<filtering>true</filtering>
									<includes>
										<include>**/*.xml</include>
									</includes>
								</resource>
							</resources>
							<delimiters>
								<delimiter>${*}</delimiter>
								<delimiter>[[*]]</delimiter>
							</delimiters>
						</configuration>
					</execution>
				</executions>
			</plugin>
			<plugin>
				<artifactId>maven-assembly-plugin</artifactId>
				<configuration>
					<appendAssemblyId>false</appendAssemblyId>
					<finalName>configuration</finalName>
					<descriptors>
						<descriptor>${basedir}/assembly.xml</descriptor>
					</descriptors>
				</configuration>
				<executions>
					<execution>
						<id>create-archive</id>
						<phase>package</phase>
						<goals>
							<goal>single</goal>
						</goals>
					</execution>
				</executions>
			</plugin>
		</plugins>
	</build>

</project>

In the above file, I have included maven-compiler-plugin for our Java resources, though it is not required for this project as there is no Java resource file.

The important plugin is maven-resources-plugin here that does the required job for filtering or replacements and copy the resource into new file under target/config folder.

I have specified the goal as copy-resources, because I will copy the XML file after replacement into the output directory target/config.

I have specified the resource directory xml from where filtering will be applied to the XML file.

Notice, I have also added two delimiters as the place holders are specified by those two delimiters in the XML file.

Finally, I have added maven-assembly-plugin to create zip file for the new XML file.

You may find more on assembly configuration and creating zip file using maven-assembly-plugin here.

Building the Project

If you execute mvn install in command line tool or from Eclipse Run As -> Maven install, then you will see the following changes on the original file under target/config directory.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<config sharedLib="library">
	<cores adminPath="/admin" hostPort="9988"
		hostContext="localhost">
		<core name="activeCustomers" instanceDir="activeCustomers"
			dataDir="/web/SearchIndex/activeCustomers" />

		<core name="carriers" instanceDir="carriers"
			dataDir="/web/SearchIndex/carriers" />

		<core name="cities" instanceDir="cities"
			dataDir="/web/SearchIndex/cities" />

		<core name="customerAddresses" instanceDir="customerAddresses"
			dataDir="/web/SearchIndex/customerAddresses" />

		<core config="config.xml" name="servicerequest_questions_en"
			instanceDir="servicerequest_questions_en" schema="schema.xml"
			dataDir="/web/SearchIndex/servicerequest_questions" />
	</cores>
</config>

You will also see a zip file configuration.zip has been created under target folder. If you open the zip file you will see that test.xml file is there inside this zip file.

Source Code

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