Support local modules.properties for custom mappings

Resolves #67

Author: jjohannes

src/main/java/org/gradlex/javamodule/dependencies/JavaModuleDependenciesExtension.java

@@ -31,6 +31,7 @@
 import org.gradle.api.file.Directory;
 import org.gradle.api.file.FileCollection;
 import org.gradle.api.file.ProjectLayout;
+import org.gradle.api.file.RegularFileProperty;
 import org.gradle.api.model.ObjectFactory;
 import org.gradle.api.provider.MapProperty;
 import org.gradle.api.provider.Property;
@@ -45,14 +46,17 @@
 import org.gradlex.javamodule.dependencies.internal.utils.ModuleInfoClassCreator;
 
 import javax.inject.Inject;
+import java.io.CharArrayReader;
 import java.io.File;
+import java.io.IOException;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.Properties;
 import java.util.stream.Collectors;
 
 import static java.util.Optional.empty;
@@ -70,6 +74,13 @@ public abstract class JavaModuleDependenciesExtension {
     private final VersionCatalogsExtension versionCatalogs;
     private final ModuleInfoCache moduleInfoCache;
 
+    /**
+     * Custom mappings can be defined in a property files in your build.
+     * The default location for this file is 'gradle/modules.properties' (relative to root project).
+     * Here, the location of the file can be changed.
+     */
+    public abstract RegularFileProperty getModulesProperties();
+
     /**
      * Register mapping from Module Name to GA Coordinates (and optionally Capability Coordinates).
      * - moduleNameToGA.put("org.slf4j", "org.slf4j:slf4j-api")
@@ -113,9 +124,25 @@ public abstract class JavaModuleDependenciesExtension {
     public JavaModuleDependenciesExtension(VersionCatalogsExtension versionCatalogs) {
         this.versionCatalogs = versionCatalogs;
         this.moduleInfoCache = getObjects().newInstance(ModuleInfoCache.class);
+        getModulesProperties().set(getProject().getRootProject().getLayout().getProjectDirectory().file("gradle/modules.properties"));
         getVersionCatalogName().convention("libs");
         getAnalyseOnly().convention(false);
         getModuleNameToGA().putAll(SharedMappings.mappings);
+        getModuleNameToGA().putAll(parsedModulesProperties().orElse(Collections.emptyMap()));
+    }
+
+    private Provider<Map<String, String>> parsedModulesProperties() {
+        return getProviders().fileContents(getModulesProperties()).getAsText().map(c -> {
+            Properties p = new Properties();
+            try {
+                p.load(new CharArrayReader(c.toCharArray()));
+            } catch (IOException e) {
+                throw new RuntimeException(e);
+            }
+            @SuppressWarnings({"rawtypes"})
+            Map<String, String> result = (Map) p;
+            return result;
+        });
     }
 
     /**

src/test/groovy/org/gradlex/javamodule/dependencies/test/CustomizationTest.groovy

@@ -34,6 +34,52 @@ class CustomizationTest extends Specification {
         result.output.contains('[jakarta.mail-2.0.1.jar, jakarta.activation-2.0.1.jar]')
     }
 
+    def "can add custom mapping via properties file (default location)"() {
+        given:
+        def customModulesPropertiesFile = file("gradle/modules.properties")
+
+        customModulesPropertiesFile << 'jakarta.mail=com.sun.mail:jakarta.mail'
+        appBuildFile << 'moduleInfo { version("jakarta.mail", "2.0.1") }'
+
+        appModuleInfoFile << '''
+            module org.gradlex.test.app { 
+                requires jakarta.mail;
+            }
+        '''
+
+        when:
+        def result = printRuntimeJars()
+
+        then:
+        result.output.contains('[jakarta.mail-2.0.1.jar, jakarta.activation-2.0.1.jar]')
+    }
+
+    def "can add custom mapping via properties file (custom location)"() {
+        given:
+        def customModulesPropertiesFile = file(".hidden/modules.properties")
+
+        customModulesPropertiesFile << 'jakarta.mail=com.sun.mail:jakarta.mail'
+        appBuildFile << 'moduleInfo { version("jakarta.mail", "2.0.1") }'
+
+        appBuildFile << '''
+            javaModuleDependencies {
+                modulesProperties.set(rootProject.layout.projectDirectory.file(".hidden/modules.properties"))
+            }
+        '''
+
+        appModuleInfoFile << '''
+            module org.gradlex.test.app { 
+                requires jakarta.mail;
+            }
+        '''
+
+        when:
+        def result = printRuntimeJars()
+
+        then:
+        result.output.contains('[jakarta.mail-2.0.1.jar, jakarta.activation-2.0.1.jar]')
+    }
+
     def "can use custom catalog"() {
         given:
         settingsFile << '''

src/test/groovy/org/gradlex/javamodule/dependencies/test/fixture/GradleBuild.groovy

@@ -34,8 +34,12 @@ class GradleBuild {
         appBuildFile << '''
             plugins {
                 id("org.gradlex.java-module-dependencies")
+                id("org.gradlex.java-module-versions")
                 id("application")
             }
+            javaModuleDependencies {
+                versionsFromPlatformAndConsistentResolution(":app", ":app")
+            }
             application {
                 mainModule.set("org.gradlex.test.app")
                 mainClass.set("org.gradlex.test.app.Main")