Fix java8 javac loading

Author: cuzfrog

maven-plugin/it/mvne

@@ -0,0 +1,4 @@
+#!/bin/sh
+
+export MAVEN_OPTS="-Xdebug -Xnoagent -Xint -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=5005 $MAVEN_OPTS"
+./mvnw "$@"

maven-plugin/src/main/java/online/sharedtype/maven/DependencyResolver.java

@@ -28,7 +28,7 @@ final class DependencyResolver {
         this.project = project;
     }
 
-    List<File> getSourceDependencies() throws MojoExecutionException {
+    List<File> getClasspathDependencies() throws MojoExecutionException {
         try {
             ArtifactTypeRegistry artifactTypeRegistry =
                 session.getRepositorySession().getArtifactTypeRegistry();

maven-plugin/src/main/java/online/sharedtype/maven/SharedTypeGenMojo.java

@@ -35,10 +35,12 @@
 /**
  * Generate types from {@link SharedType} annotated classes.
  * See <a href="https://github.com/SharedType/sharedtype">SharedType</a> for details.
+ *
  * @author Cause Chung
  */
 @Mojo(name = "gen")
 public final class SharedTypeGenMojo extends AbstractMojo {
+    private static final String JAVA8_VERSION = "1.8";
     private static final List<String> DEFAULT_COMPILER_OPTIONS = Arrays.asList("-proc:only", "-Asharedtype.enabled=true");
     private @Inject RepositorySystem repositorySystem;
 
@@ -84,13 +86,13 @@ public void execute() throws MojoExecutionException, MojoFailureException {
                 Files.createDirectories(outputDirPath);
             }
             fileManager.setLocation(StandardLocation.SOURCE_OUTPUT, Collections.singleton(outputDirPath.toFile()));
-            fileManager.setLocation(StandardLocation.CLASS_PATH, dependencyResolver.getSourceDependencies());
+            fileManager.setLocation(StandardLocation.CLASS_PATH, dependencyResolver.getClasspathDependencies());
         } catch (Exception e) {
             throw new MojoExecutionException(e);
         }
         Iterable<? extends JavaFileObject> sources = fileManager.getJavaFileObjectsFromFiles(walkAllSourceFiles());
 
-        try(SharedTypeLogger logger = new SharedTypeLogger(getLog())) {
+        try (SharedTypeLogger logger = new SharedTypeLogger(getLog())) {
             JavaCompiler.CompilationTask task = compiler.getTask(logger, fileManager, diagnosticListener, getCompilerOptions(), null, sources);
             SharedTypeAnnotationProcessor annotationProcessor = new SharedTypeAnnotationProcessor();
             annotationProcessor.setUserProps(properties);
@@ -124,7 +126,18 @@ private List<String> getCompilerOptions() throws MojoFailureException {
     }
 
     private static JavaCompiler getJavaCompiler() throws MojoExecutionException {
-        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
+        String javaVersion = System.getProperty("java.specification.version");
+        JavaCompiler compiler;
+        if (JAVA8_VERSION.equals(javaVersion)) {
+            try {
+                Class<?> javacToolClass = SharedTypeAnnotationProcessor.class.getClassLoader().loadClass("com.sun.tools.javac.api.JavacTool");
+                compiler = (JavaCompiler) javacToolClass.getConstructor().newInstance();
+            } catch (Exception e) {
+                throw new MojoExecutionException("Failed to load JavaCompiler.", e);
+            }
+        } else {
+            compiler = ToolProvider.getSystemJavaCompiler();
+        }
         if (compiler != null) {
             return compiler;
         }

processor/pom.xml

@@ -1,5 +1,6 @@
 <?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">
+<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>
     <parent>
         <groupId>online.sharedtype</groupId>
@@ -63,6 +64,50 @@
         </dependency>
     </dependencies>
 
+    <!-- For JDK 8, need to explicit add tools.jar dependency for Tree API -->
+    <profiles>
+        <profile>
+            <id>jdk-tools-jar-env-var</id>
+            <activation>
+                <activeByDefault>true</activeByDefault>
+                <file>
+                    <exists>${JAVA_HOME}/lib/tools.jar</exists>
+                </file>
+            </activation>
+            <properties>
+                <!--suppress UnresolvedMavenProperty -->
+                <toolsjar>${JAVA_HOME}/lib/tools.jar</toolsjar>
+            </properties>
+        </profile>
+        <profile>
+            <id>jdk-tools-jar-sys-prop</id>
+            <activation>
+                <activeByDefault>false</activeByDefault>
+                <file>
+                    <exists>${java.home}/../lib/tools.jar</exists>
+                </file>
+            </activation>
+            <properties>
+                <toolsjar>${java.home}/../lib/tools.jar</toolsjar>
+            </properties>
+        </profile>
+        <profile>
+            <id>java8-jdk-tools-jar</id>
+            <activation>
+                <jdk>1.8</jdk>
+            </activation>
+            <dependencies>
+                <dependency>
+                    <groupId>jdk.tools</groupId>
+                    <artifactId>jdk.tools</artifactId>
+                    <version>jdk1.8.0</version>
+                    <scope>system</scope>
+                    <systemPath>${toolsjar}</systemPath>
+                </dependency>
+            </dependencies>
+        </profile>
+    </profiles>
+
     <build>
         <plugins>
             <plugin>