Support runners other than DirectRunner for :examples:java:execute

examples/java/build.gradle

@@ -41,9 +41,14 @@ artifact includes all Apache Beam Java SDK examples."""
  * for details.
  */
 def preCommitRunners = ["directRunner", "flinkRunner", "sparkRunner"]
+// The following runners have configuration created but not added to preCommit
+def nonPreCommitRunners = ["dataflowRunner", "prismRunner"]
 for (String runner : preCommitRunners) {
   configurations.create(runner + "PreCommit")
 }
+for (String runner: nonPreCommitRunners) {
+  configurations.create(runner + "PreCommit")
+}
 configurations.sparkRunnerPreCommit {
   // Ban certain dependencies to prevent a StackOverflow within Spark
   // because JUL -> SLF4J -> JUL, and similarly JDK14 -> SLF4J -> JDK14
@@ -123,6 +128,10 @@ dependencies {
   flinkRunnerPreCommit project(":runners:flink:${project.ext.latestFlinkVersion}")
   sparkRunnerPreCommit project(":runners:spark:3")
   sparkRunnerPreCommit project(":sdks:java:io:hadoop-file-system")
+  dataflowRunnerPreCommit project(":runners:google-cloud-dataflow-java")
+  dataflowRunnerPreCommit project(":runners:google-cloud-dataflow-java:worker") // v2 worker
+  dataflowRunnerPreCommit project(":sdks:java:harness") // v2 worker
+  prismRunnerPreCommit project(":runners:prism:java")
 
   // Add dependency if requested on command line for runner
   if (project.hasProperty("runnerDependency")) {
@@ -167,11 +176,37 @@ task preCommit() {
   }
 }
 
+/*
+ * A convenient task to run individual example directly on Beam repo.
+ *
+ * Usage:
+ * ./gradlew :examples:java:execute -PmainClass=org.apache.beam.examples.<ClassName>`\
+ *  -Pexec.args="runner=[DataflowRunner|DirectRunner|FlinkRunner|SparkRunner|PrismRunner] \
+ * <pipeline options>"
+ */
 tasks.create(name:"execute", type:JavaExec) {
-  main = project.hasProperty("mainClass") ? project.getProperty("mainClass") : "NONE"
-  classpath = sourceSets.main.runtimeClasspath
+  mainClass = project.hasProperty("mainClass") ? project.getProperty("mainClass") : "NONE"
+  def execArgs =  project.findProperty("exec.args")
+  String runner
+  if (execArgs) {
+    // configure runner dependency from args
+    def runnerPattern = /runner[ =]([A-Za-z]+)/
+    def matcher = execArgs =~ runnerPattern
+    if (matcher) {
+      runner = matcher[0][1]
+      runner = runner.substring(0, 1).toLowerCase() + runner.substring(1);
+      if (!(runner in (preCommitRunners + nonPreCommitRunners))) {
+        throw new GradleException("Unsupported runner: " + runner)
+      }
+    }
+  }
+  if (runner) {
+    classpath = sourceSets.main.runtimeClasspath + configurations."${runner}PreCommit"
+  } else {
+    classpath = sourceSets.main.runtimeClasspath
+  }
   systemProperties System.getProperties()
-  args project.hasProperty("exec.args") ? project.getProperty("exec.args").split() : []
+  args execArgs ? execArgs.split() : []
 }
 
 // Run this task to validate the Java environment setup for contributors