Package com.norconex.commons.lang

Class SystemUtil

java.lang.Object
com.norconex.commons.lang.SystemUtil
public final class SystemUtil extends Object
System-related convenience methods.
Since:
2.0.0

  • Method Details

    • withOutputCapture

      public static <T> SystemUtil.Captured<T> withOutputCapture(Callable<T> callable)
      Same as callAndCaptureOutput(Callable) but with no thread-safety guarantee. This method is not synchronized.
      Type Parameters:
      T - the type of the return value
      Parameters:
      callable - the code to execute
      Returns:
      captured return value and standard output/error
      Throws:
      SystemUtil.UncheckedCallableException - wrapper around any Callable exception
      Since:
      3.0.0

    • callAndCaptureOutput

      public static <T> SystemUtil.Captured<T> callAndCaptureOutput(Callable<T> callable)
      Executes a Callable and return its value along with any standard output or error (i.e., STDOUT/STDERR). While this method is synchronized, nothing prevent other threads from also writing to System.out or System.err. For this reason this method should not be considered thread-safe.
      Type Parameters:
      T - the type of the return value
      Parameters:
      callable - the code to execute
      Returns:
      captured return value and standard output/error
      Throws:
      SystemUtil.UncheckedCallableException - wrapper around any Callable exception
      Since:
      3.0.0

    • runAndCaptureOutput

      public static SystemUtil.Captured<Void> runAndCaptureOutput(Runnable runnable)
      Executes a Runnable and return any standard output or error (i.e., STDOUT/STDERR). While this method is synchronized, nothing prevent other threads from also writing to System.out or System.err. For this reason this method should not be considered thread-safe.
      Parameters:
      runnable - the code to execute
      Returns:
      captured standard output/error
      Since:
      3.0.0

    • runWithProperty

      public static void runWithProperty(String name, String value, Runnable runnable)

      Executes the supplied Runnable after setting the system property and then resets that system property. This method is synchronized to make sure setting the property does not affect other threads. The system property is restored to its original value (if any) after execution. Useful when the invoked code expects a system property that is configurable and may change from one thread to another.

      null handling

      This method is null-safe. If the runnable is null, invoking this method has no effect. If the property name is null, the runnable is invoked without setting any property beforehand. If the property value is null, it will temporary clear any existing system property with the same name (if any) for the duration of the execution.

      Parameters:
      name - system property name
      value - system property value
      runnable - code to run with the system property set

    • callWithProperty

      public static <T> T callWithProperty(String name, String value, Callable<T> callable)

      Executes the supplied Callable after setting the system property and then resets that system property. This method is synchronized to make sure setting the property does not affect other threads. The system property is restored to its original value (if any) after execution. Useful when the invoked code expects a system property that is configurable and may change from one thread to another.

      null handling

      This method is null-safe. If the callable is null, invoking this method returns null. If the property name is null, the runnable is invoked without setting any property beforehand. If the property value is null, it will temporary clear any existing system property with the same name (if any) for the duration of the execution.

      Type Parameters:
      T - class type of return value
      Parameters:
      name - system property name
      value - system property value
      callable - code to run with the system property set
      Returns:
      the callable return value
      Throws:
      SystemUtil.UncheckedCallableException - wrapper around any Callable exception

    • getEnvironmentOrProperty

      public static String getEnvironmentOrProperty(String name)
      Gets the environment variable or system property matching the exact name, or a supported variant. Same as invoking getEnvironment(String) and if null, invoking getProperty(String).
      Parameters:
      name - property or environment name
      Returns:
      property or environment value

    • getPropertyOrEnvironment

      public static String getPropertyOrEnvironment(String name)
      Gets the system property or environment variable matching the exact name, or a supported variant. Same as invoking getProperty(String) and if null, invoking getEnvironment(String).
      Parameters:
      name - environment or property name
      Returns:
      environment or property value

    • getEnvironment

      public static String getEnvironment(String name)
      Gets the value of the specified environment variable matching the exact name, or a supported variant. First, it looks for a direct environment variable name match, as with System.getenv(String). If no matches are found, it will iterate through all environment variables names and compare them all with the requested name, but only after stripping all non alpha-numeric characters and ignoring case.
      Parameters:
      name - the name of the environment variable
      Returns:
      environment variable value

    • getProperty

      public static String getProperty(String name)
      Gets the value of the system property matching the exact name, or a supported variant. First, it looks for a direct property name match, as with System.getProperty(String). If no matches are found, it will iterate through all system property names and compare them all with the requested name, but only after stripping all non alpha-numeric characters and ignoring case.
      Parameters:
      name - the name of the system property
      Returns:
      system property value