SONAR-1800: Fix issue with ClassLoader for Maven 3.x and Java 1.5

* Restore context ClassLoader after execution of Maven plugin.

* Add abstract implementation of MavenPluginExecutor to reduce duplications
  in concrete implementations for different Maven versions.

2 files changed, 93 insertions, 0 deletions

diff --git a/sonar-batch/src/main/java/org/sonar/batch/AbstractMavenPluginExecutor.java b/sonar-batch/src/main/java/org/sonar/batch/AbstractMavenPluginExecutor.java
new file mode 100644
index 00000000000..7e7bf73b28f
--- /dev/null
+++ b/sonar-batch/src/main/java/org/sonar/batch/AbstractMavenPluginExecutor.java
@@ -0,0 +1,50 @@
+package org.sonar.batch;
+
+import org.apache.maven.project.MavenProject;
+import org.sonar.api.batch.maven.MavenPlugin;
+import org.sonar.api.batch.maven.MavenPluginHandler;
+import org.sonar.api.resources.Project;
+import org.sonar.api.utils.SonarException;
+import org.sonar.api.utils.TimeProfiler;
+
+/**
+ * Abstract implementation of {@link MavenPluginExecutor} to reduce duplications in concrete implementations for different Maven versions.
+ */
+public abstract class AbstractMavenPluginExecutor implements MavenPluginExecutor {
+
+  public final MavenPluginHandler execute(Project project, MavenPluginHandler handler) {
+    for (String goal : handler.getGoals()) {
+      MavenPlugin plugin = MavenPlugin.getPlugin(project.getPom(), handler.getGroupId(), handler.getArtifactId());
+      execute(project, getGoal(handler.getGroupId(), handler.getArtifactId(), plugin.getPlugin().getVersion(), goal));
+    }
+    return handler;
+  }
+
+  public final void execute(Project project, String goal) {
+    TimeProfiler profiler = new TimeProfiler().start("Execute " + goal);
+    ClassLoader currentClassLoader = Thread.currentThread().getContextClassLoader();
+    try {
+      concreteExecute(project.getPom(), goal);
+    } catch (Exception e) {
+      throw new SonarException("Unable to execute maven plugin", e);
+    } finally {
+      // Reset original ClassLoader that may have been changed during Maven Execution (see SONAR-1800)
+      Thread.currentThread().setContextClassLoader(currentClassLoader);
+      profiler.stop();
+    }
+  }
+
+  public abstract void concreteExecute(MavenProject pom, String goal) throws Exception;
+
+  static String getGoal(String groupId, String artifactId, String version, String goal) {
+    String defaultVersion = (version == null ? "" : version);
+    return new StringBuilder()
+        .append(groupId).append(":")
+        .append(artifactId).append(":")
+        .append(defaultVersion)
+        .append(":")
+        .append(goal)
+        .toString();
+  }
+
+}
diff --git a/sonar-batch/src/test/java/org/sonar/batch/AbstractMavenPluginExecutorTest.java b/sonar-batch/src/test/java/org/sonar/batch/AbstractMavenPluginExecutorTest.java
new file mode 100644
index 00000000000..e86516f0284
--- /dev/null
+++ b/sonar-batch/src/test/java/org/sonar/batch/AbstractMavenPluginExecutorTest.java
@@ -0,0 +1,43 @@
+package org.sonar.batch;
+
+import org.junit.Test;
+import org.sonar.api.batch.maven.MavenPlugin;
+import org.sonar.api.batch.maven.MavenPluginHandler;
+import org.sonar.api.resources.Project;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+public class AbstractMavenPluginExecutorTest {
+
+  @Test
+  public void pluginVersionIsOptional() {
+    assertThat(AbstractMavenPluginExecutor.getGoal("group", "artifact", null, "goal"), is("group:artifact::goal"));
+  }
+
+  static class FakeCheckstyleMavenPluginHandler implements MavenPluginHandler {
+    public String getGroupId() {
+      return "org.apache.maven.plugins";
+    }
+
+    public String getArtifactId() {
+      return "maven-checkstyle-plugin";
+    }
+
+    public String getVersion() {
+      return "2.2";
+    }
+
+    public boolean isFixedVersion() {
+      return false;
+    }
+
+    public String[] getGoals() {
+      return new String[] { "checkstyle" };
+    }
+
+    public void configure(Project project, MavenPlugin plugin) {
+    }
+  }
+
+}