ClassRunner.java

package jetbrains.mps.execution.lib.startup;

/*Generated by MPS */

import java.util.List;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.io.File;
import java.net.MalformedURLException;
import java.net.URLClassLoader;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;
import java.io.LineNumberReader;
import java.io.FileReader;

public class ClassRunner {
  public static final String CLASS_PREFIX = "c";
  public static final String FILE_PREFIX = "f";
  public static final String CLASSPATH_PREFIX = "p";
  public ClassRunner() {
  }

  public static void main(String[] args) {
    String className = null;
    String fileName = null;
    String classpathFileName = null;

    // parse args 
    for (int i = 0; i < args.length; i++) {
      if (getCommandLineFromPrefix(CLASS_PREFIX).equals(args[i])) {
        if (i >= args.length - 1) {
          System.err.println("Class name after " + getCommandLineFromPrefix(ClassRunner.CLASS_PREFIX) + " expected.");
          return;
        }
        className = args[i + 1];
        i++;
      } else if (getCommandLineFromPrefix(FILE_PREFIX).equals(args[i])) {
        if (i >= args.length - 1) {
          System.err.println("File name after " + getCommandLineFromPrefix(FILE_PREFIX) + " expected.");
          return;
        }
        fileName = args[i + 1];
      } else if (getCommandLineFromPrefix(CLASSPATH_PREFIX).equals(args[i])) {
        if (i >= args.length - 1) {
          System.err.println("Classpath file name after " + getCommandLineFromPrefix(CLASSPATH_PREFIX) + " expected.");
          return;
        }
        classpathFileName = args[i + 1];
      }
    }

    // check if empty 
    if (className == null || className.isEmpty()) {
      System.err.println("Main class name expected (example " + getCommandLineFromPrefix(CLASS_PREFIX) + " com.mycompany.ClassName).");
      return;
    } else if (fileName == null || fileName.isEmpty()) {
      System.err.println("Path to file with arguments expected (example " + getCommandLineFromPrefix(ClassRunner.FILE_PREFIX) + " /path/to/file).");
      return;
    }

    // read 
    List<String> fileContents;
    try {
      fileContents = readArguments(fileName);
    } catch (IOException e) {
      System.err.println("Could not read file with arguments.");
      e.printStackTrace();
      return;
    }

    List<URL> classPath = new ArrayList<URL>();
    if (classpathFileName != null && !(classpathFileName.isEmpty())) {
      try {
        for (String cp : readArguments(classpathFileName)) {
          try {
            classPath.add(new File(cp).toURI().toURL());
          } catch (MalformedURLException e) {
            e.printStackTrace();
          }
        }
      } catch (IOException e) {
        e.printStackTrace();
      }
    }

    // execute 
    try {
      URLClassLoader classLoader = new URLClassLoader(classPath.<URL>toArray(new URL[classPath.size()]));
      Thread.currentThread().setContextClassLoader(classLoader);
      Class<?> classToStart = classLoader.loadClass(className);
      Method method = classToStart.getMethod("main", args.getClass());
      method.invoke(null, new Object[]{fileContents.<String>toArray(new String[fileContents.size()])});
    } catch (ClassNotFoundException c) {
      System.err.println("Class " + className + " was not found.");
      c.printStackTrace();
    } catch (NoSuchMethodException e) {
      System.err.println("Class " + className + " does not have main method.");
      e.printStackTrace();
    } catch (InvocationTargetException e) {
      e.getCause().printStackTrace();
    } catch (IllegalAccessException e) {
      System.err.println("Method main in class " + className + " is not public.");
      e.printStackTrace();
    }
  }

  public static List<String> readArguments(String fileName) throws IOException {
    List<String> result = new ArrayList<String>();
    LineNumberReader reader = new LineNumberReader(new FileReader(fileName));
    while (true) {
      String line = reader.readLine();
      if (line == null) {
        break;
      }
      if (line.isEmpty()) {
        continue;
      }
      result.add(line);
    }
    return result;
  }

  private static String getCommandLineFromPrefix(String prefix) {
    return "-" + prefix;
  }
}