// --------------------------------------------------------------------------
  //  context environment
  // --------------------------------------------------------------------------
  
  /**
   * Creates an execution environment that represents the context in which the program is
   * currently executed. If the program is invoked standalone, this method returns a local
   * execution environment. If the program is invoked from within the command line client
   * to be submitted to a cluster, this method returns the execution environment of this cluster.
   */
  def getExecutionEnvironment: StreamExecutionEnvironment = {
    new StreamExecutionEnvironment(JavaEnv.getExecutionEnvironment)
  }

// --------------------------------------------------------------------------
//  local environment
// --------------------------------------------------------------------------


/**
* Creates a local execution environment. The local execution environment will run the
* program in a multi-threaded fashion in the same JVM as the environment was created in.
*
* This method sets the environment's default parallelism to given parameter, which
* defaults to the value set via [[setDefaultLocalParallelism(Int)]].
*/
def createLocalEnvironment(parallelism: Int = JavaEnv.getDefaultLocalParallelism):
  StreamExecutionEnvironment = {
new StreamExecutionEnvironment(JavaEnv.createLocalEnvironment(parallelism))
}

// --------------------------------------------------------------------------
  //  remote environment
  // --------------------------------------------------------------------------


  /**
   * Creates a remote execution environment. The remote environment sends (parts of) the program to
   * a cluster for execution. Note that all file paths used in the program must be accessible from
   * the cluster. The execution will use the cluster's default parallelism, unless the
   * parallelism is set explicitly via [[StreamExecutionEnvironment.setParallelism()]].
   *
   * @param host The host name or address of the master (JobManager),
   *             where the program should be executed.
   * @param port The port of the master (JobManager), where the program should be executed.
   * @param jarFiles The JAR files with code that needs to be shipped to the cluster. If the
   *                 program uses
   *                 user-defined functions, user-defined input formats, or any libraries,
   *                 those must be
   *                 provided in the JAR files.
   */
  def createRemoteEnvironment(host: String, port: Int, jarFiles: String*):
  StreamExecutionEnvironment = {
    new StreamExecutionEnvironment(JavaEnv.createRemoteEnvironment(host, port, jarFiles: _*))
  }

//1.获取一个执行环境，上下文（execution environment）；
val env = StreamExecutionEnvironment.getExecutionEnvironment

 //1.获取一个执行环境，上下文（execution environment）；
    val env = StreamExecutionEnvironment.getExecutionEnvironment