From aa2822c5fc3360afef6fa4f237c9b69d4c3d372e Mon Sep 17 00:00:00 2001 From: Amitabh Mandal Date: Thu, 30 Aug 2018 23:38:21 +0530 Subject: [PATCH] BAEL-1991 - Understanding Process (#4863) * Understanding Process * Refactored names * Refactored junit names based on document guidance * Added alive * renamed junits as behavior Driven requirements * Added alive method junit * added waitFor method time interval junit * getOutputStream * changed exception * dummy commit * Dummy Commit with blank lines * Fixed assert and commented @Test * fixed asserts * Replaced System.out.println with logging * replaced system.out.println with logging * Dummy commit to ensure clean build * Renamed Junit * Fixed extra spaces and typo * Uncommented @Test for 3 methods --- .../baeldung/java9/process/ChildProcess.java | 15 +++ .../java9/process/OutputStreamExample.java | 16 +++ .../process/ProcessCompilationError.java | 7 + .../java9/process/ProcessUnderstanding.java | 110 ++++++++++++++++ .../process/ProcessUnderstandingTest.java | 121 ++++++++++++++++++ 5 files changed, 269 insertions(+) create mode 100644 core-java-9/src/main/java/com/baeldung/java9/process/ChildProcess.java create mode 100644 core-java-9/src/main/java/com/baeldung/java9/process/OutputStreamExample.java create mode 100644 core-java-9/src/main/java/com/baeldung/java9/process/ProcessCompilationError.java create mode 100644 core-java-9/src/main/java/com/baeldung/java9/process/ProcessUnderstanding.java create mode 100644 core-java-9/src/test/java/com/baeldung/java9/process/ProcessUnderstandingTest.java diff --git a/core-java-9/src/main/java/com/baeldung/java9/process/ChildProcess.java b/core-java-9/src/main/java/com/baeldung/java9/process/ChildProcess.java new file mode 100644 index 0000000000..46c2e688ce --- /dev/null +++ b/core-java-9/src/main/java/com/baeldung/java9/process/ChildProcess.java @@ -0,0 +1,15 @@ +package com.baeldung.java9.process; + +import java.util.Scanner; +import java.util.logging.Level; +import java.util.logging.Logger; + +public class ChildProcess { + + public static void main(String[] args) { + @SuppressWarnings("resource") + Scanner input = new Scanner(System.in); + Logger log = Logger.getLogger(ChildProcess.class.getName()); + log.log(Level.INFO, input.nextLine()); + } +} diff --git a/core-java-9/src/main/java/com/baeldung/java9/process/OutputStreamExample.java b/core-java-9/src/main/java/com/baeldung/java9/process/OutputStreamExample.java new file mode 100644 index 0000000000..443847916a --- /dev/null +++ b/core-java-9/src/main/java/com/baeldung/java9/process/OutputStreamExample.java @@ -0,0 +1,16 @@ +package com.baeldung.java9.process; + +import java.util.logging.Level; +import java.util.logging.Logger; + +public class OutputStreamExample { + + public static void main(String[] args) { + Logger log = Logger.getLogger(OutputStreamExample.class.getName()); + log.log(Level.INFO, Integer.toString(sum(1,2))); + } + + public static int sum(int a, int b) { + return a + b; + } +} diff --git a/core-java-9/src/main/java/com/baeldung/java9/process/ProcessCompilationError.java b/core-java-9/src/main/java/com/baeldung/java9/process/ProcessCompilationError.java new file mode 100644 index 0000000000..8b6ae0b441 --- /dev/null +++ b/core-java-9/src/main/java/com/baeldung/java9/process/ProcessCompilationError.java @@ -0,0 +1,7 @@ +package com.baeldung.java9.process; + +public class ProcessCompilationError { + //This method has been written to generate error to display + //how process errorStream() can consume error + public static void(); +} diff --git a/core-java-9/src/main/java/com/baeldung/java9/process/ProcessUnderstanding.java b/core-java-9/src/main/java/com/baeldung/java9/process/ProcessUnderstanding.java new file mode 100644 index 0000000000..74101ba3da --- /dev/null +++ b/core-java-9/src/main/java/com/baeldung/java9/process/ProcessUnderstanding.java @@ -0,0 +1,110 @@ +package com.baeldung.java9.process; + +import java.io.BufferedReader; +import java.io.IOException; +import java.io.InputStreamReader; +import java.io.OutputStreamWriter; +import java.io.Writer; +import java.util.Optional; +import java.util.logging.Level; +import java.util.logging.Logger; + +public class ProcessUnderstanding { + + public static int compileAndRunJavaProgram() throws IOException { + Process process = Runtime.getRuntime() + .exec("javac -cp src src\\main\\java\\com\\baeldung\\java9\\process\\OutputStreamExample.java"); + process = Runtime.getRuntime() + .exec("java -cp src/main/java com.baeldung.java9.process.OutputStreamExample"); + BufferedReader output = new BufferedReader(new InputStreamReader(process.getInputStream())); + int value = Integer.parseInt(output.readLine()); + return value; + } + + public static String getErrorStreamExample() throws IOException { + Process process = Runtime.getRuntime() + .exec("javac -cp src src\\main\\java\\com\\baeldung\\java9\\process\\ProcessCompilationError.java"); + BufferedReader error = new BufferedReader(new InputStreamReader(process.getErrorStream())); + String errorString = error.readLine(); + return errorString; + } + + public static void creatingNewProcess() throws IOException { + ProcessBuilder builder = new ProcessBuilder("notepad.exe"); + Process process = builder.start(); + } + + public static int filterProcessWithStreamsInSpecificRangeReturnCount() { + return (int) ProcessHandle.allProcesses() + .filter(ph -> (ph.pid() > 10000 && ph.pid() < 50000)) + .count(); + } + + public static void destroyingProcessCreatedBySameProcess() throws IOException, InterruptedException { + ProcessBuilder builder = new ProcessBuilder("notepad.exe"); + Process process = builder.start(); + Thread.sleep(10000); + process.destroy(); + } + + public static void destroyingProcessCreatedByDifferentProcess() { + // find out the process id of current running task by checking + // task manager in windows and enter the integer value + Optional optionalProcessHandle = ProcessHandle.of(5232); + ProcessHandle processHandle = optionalProcessHandle.get(); + processHandle.destroy(); + } + + public static int waitForExample() throws IOException, InterruptedException { + ProcessBuilder builder = new ProcessBuilder("notepad.exe"); + Process process = builder.start(); + return process.waitFor(); + } + + public static int exitValueExample() throws IOException { + ProcessBuilder builder = new ProcessBuilder("notepad.exe"); + Process process = builder.start(); + process.destroy(); + return process.exitValue(); + } + + public static void destroyExample() throws IOException, InterruptedException { + ProcessBuilder builder = new ProcessBuilder("notepad.exe"); + Process process = builder.start(); + Thread.sleep(10000); + process.destroy(); + } + + public static void destroyForciblyExample() throws IOException, InterruptedException { + ProcessBuilder builder = new ProcessBuilder("notepad.exe"); + Process process = builder.start(); + Thread.sleep(10000); + process.destroy(); + if (process.isAlive()) { + process.destroyForcibly(); + } + } + + public static void outputStreamDemo() throws IOException, InterruptedException { + Logger log = Logger.getLogger(ProcessUnderstanding.class.getName()); + Process pr = Runtime.getRuntime() + .exec("javac -cp src src\\main\\java\\com\\baeldung\\java9\\process\\ChildProcess.java"); + final Process process = Runtime.getRuntime() + .exec("java -cp src/main/java com.baeldung.java9.process.ChildProcess"); + try (Writer w = new OutputStreamWriter(process.getOutputStream(), "UTF-8")) { + w.write("send to child\n"); + } + new Thread(() -> { + try { + int c; + while ((c = process.getInputStream() + .read()) != -1) + System.out.write((byte) c); + } catch (Exception e) { + e.printStackTrace(); + } + }).start(); + // send to child + log.log(Level.INFO, "rc=" + process.waitFor()); + } +} diff --git a/core-java-9/src/test/java/com/baeldung/java9/process/ProcessUnderstandingTest.java b/core-java-9/src/test/java/com/baeldung/java9/process/ProcessUnderstandingTest.java new file mode 100644 index 0000000000..2f61846c1c --- /dev/null +++ b/core-java-9/src/test/java/com/baeldung/java9/process/ProcessUnderstandingTest.java @@ -0,0 +1,121 @@ +package com.baeldung.java9.process; + +import static org.assertj.core.api.Assertions.assertThat; +import static org.junit.Assert.assertTrue; +import static org.junit.jupiter.api.Assertions.*; + +import java.io.BufferedReader; +import java.io.IOException; +import java.io.InputStreamReader; +import java.lang.String; +import java.util.Optional; +import java.util.concurrent.TimeUnit; +import java.lang.Integer; + +import org.junit.jupiter.api.Test; + +class ProcessUnderstandingTest { + + @Test + public void givenSourceProgram_whenExecutedFromAnotherProgram_thenSourceProgramOutput3() throws IOException { + Process process = Runtime.getRuntime() + .exec("javac -cp src src\\main\\java\\com\\baeldung\\java9\\process\\OutputStreamExample.java"); + process = Runtime.getRuntime() + .exec("java -cp src/main/java com.baeldung.java9.process.OutputStreamExample"); + BufferedReader output = new BufferedReader(new InputStreamReader(process.getInputStream())); + int value = Integer.parseInt(output.readLine()); + assertEquals(3, value); + } + + @Test + public void givenSourceProgram_whenReadingInputStream_thenFirstLineEquals3() throws IOException { + Process process = Runtime.getRuntime() + .exec("javac -cp src src\\main\\java\\com\\baeldung\\java9\\process\\OutputStreamExample.java"); + process = Runtime.getRuntime() + .exec("java -cp src/main/java com.baeldung.java9.process.OutputStreamExample"); + BufferedReader output = new BufferedReader(new InputStreamReader(process.getInputStream())); + int value = Integer.parseInt(output.readLine()); + assertEquals(3, value); + } + + @Test + public void givenSubProcess_whenEncounteringError_thenErrorStreamNotNull() throws IOException { + Process process = Runtime.getRuntime() + .exec("javac -cp src src\\main\\java\\com\\baeldung\\java9\\process\\ProcessCompilationError.java"); + BufferedReader error = new BufferedReader(new InputStreamReader(process.getErrorStream())); + String errorString = error.readLine(); + assertNotNull(errorString); + } + + //@Test - windows specific + public void givenSubProcess_thenStartSuccessIsAlive() throws IOException { + ProcessBuilder builder = new ProcessBuilder("notepad.exe"); + assertTrue(builder.start().isAlive()); + } + + //@Test - windows specific + public void givenSubProcess_whenDestroying_thenProcessNotAlive() throws IOException, InterruptedException { + ProcessBuilder builder = new ProcessBuilder("notepad.exe"); + Process process = builder.start(); + Thread.sleep(10000); + process.destroy(); + assertFalse(process.isAlive()); + } + + //@Test - windows specific + public void givenSubProcess_whenAlive_thenDestroyForcibly() throws IOException, InterruptedException { + ProcessBuilder builder = new ProcessBuilder("notepad.exe"); + Process process = builder.start(); + Thread.sleep(10000); + process.destroy(); + if (process.isAlive()) { + process.destroyForcibly(); + } + assertFalse(process.isAlive()); + } + + //@Test - windows specific + public void givenSubProcess_checkAlive() throws IOException, InterruptedException { + ProcessBuilder builder = new ProcessBuilder("notepad.exe"); + Process process = builder.start(); + Thread.sleep(10000); + process.destroy(); + assertFalse(process.isAlive()); + } + + @Test + public void givenProcessNotCreated_fromWithinJavaApplicationDestroying_thenProcessNotAlive() { + Optional optionalProcessHandle = ProcessHandle.of(5232); + ProcessHandle processHandle = optionalProcessHandle.get(); + processHandle.destroy(); + assertFalse(processHandle.isAlive()); + } + + //@Test - windows specific + public void givenSubProcess_whenCurrentThreadWaitsIndefinitelyuntilSubProcessEnds_thenProcessWaitForReturnsGrt0() throws IOException, InterruptedException { + ProcessBuilder builder = new ProcessBuilder("notepad.exe"); + Process process = builder.start(); + assertThat(process.waitFor() >= 0); + } + + //@Test - windows specific + public void givenSubProcess_whenCurrentThreadWaitsAndSubProcessNotTerminated_thenProcessWaitForReturnsFalse() throws IOException, InterruptedException { + ProcessBuilder builder = new ProcessBuilder("notepad.exe"); + Process process = builder.start(); + assertFalse(process.waitFor(1, TimeUnit.SECONDS)); + } + + //@Test - windows specific + public void givenSubProcess_whenCurrentThreadWillNotWaitIndefinitelyforSubProcessToEnd_thenProcessExitValueReturnsGrt0() throws IOException { + ProcessBuilder builder = new ProcessBuilder("notepad.exe"); + Process process = builder.start(); + assertThat(process.exitValue() >= 0); + } + + @Test + public void givenRunningProcesses_whenFilterOnProcessIdRange_thenGetSelectedProcessPid() { + assertThat(((int) ProcessHandle.allProcesses() + .filter(ph -> (ph.pid() > 10000 && ph.pid() < 50000)) + .count()) > 0); + } +}