วิธี terminate/destroy process ด้วย Process API ใน Java 9

ใน Java 9 Process API รองรับวิธีง่ายๆ ในการได้ข้อมูลมากมายเกี่ยวกับ process ProcessHandle interface ระบุและให้การควบคุม native processes รวมถึงเมธอดตรวจสอบ liveness และ destroy processes ในขณะที่ ProcessHandle.Info interface ให้ snapshot ข้อมูลของ process ต้องทำลาย process ด้วยเมธอด destroy() ของ ProcessHandle interface

ตัวอย่าง: ทำลาย process

import java.io.File;
import java.io.IOException;
import java.util.Objects;

public class DestroyProcessTest {
    public static void main(String[] args) throws InterruptedException {
        System.out.println("---------------------------");
        System.out.println("Destroy Process:");
        
        final String javaCmd = getJavaCmdFromParent();
        final String classpath = getClassPathFromParent();
        
        try {
            final Process process = new ProcessBuilder(javaCmd, "-cp", classpath, DestroyProcessTest.class.getName()).start();
            ProcessHandle processHandle = process.toHandle();
            printInfo(processHandle);
            destroyProcess(processHandle);
            Thread.sleep(1000);
            
            System.out.println("---------------------------");
            System.out.println("After destroying the process:");
            printInfo(processHandle);
        } catch(IOException e) {
            e.printStackTrace();
        }
    }
    
    private static String getClassPathFromParent() {
        return System.getProperty("java.class.path", "./*");
    }
    
    private static String getJavaCmdFromParent() {
        return Objects.isNull(System.getProperty("java.home")) ? "java" : 
            String.format("%s%sbin%sjava", System.getProperty("java.home"), File.separator, File.separator);
    }
    
    private static void destroyProcess(ProcessHandle processHandle) throws IllegalStateException {
        System.out.println("Ready to destroy Process with id: " + processHandle.pid());
        processHandle.destroy();
    }
    
    private static void printInfo(ProcessHandle processHandle) {
        System.out.println("---------");
        System.out.println("Id: " + processHandle.pid());
        System.out.println("isAlive(): " + processHandle.isAlive());
        System.out.println("isSupportsNormalTermination(): " + processHandle.supportsNormalTermination());
        
        ProcessHandle.Info processInfo = processHandle.info();
        System.out.println("Info: " + processInfo.toString());
        System.out.println("Info arguments().isPresent(): " + processInfo.arguments().isPresent());
        System.out.println("Info command().isPresent(): " + processInfo.command().isPresent());
        System.out.println("Info totalCpuDuration().isPresent(): " + processInfo.totalCpuDuration().isPresent());
        System.out.println("Info user().isPresent(): " + processInfo.user().isPresent());
    }
}

ผลลัพธ์

---------------------------
Destroy Process:
---------
Id: 4384
isAlive(): true
isSupportsNormalTermination(): false
Info: [user: Optional[Tutorialspoint\User], cmd: C:\Program Files\Java\jdk-9.0.4\bin\java.exe, startTime: Optional[2020-03-06T10:58:53.210Z], totalTime: Optional[PT0.046875S]]
Info arguments().isPresent(): false
Info command().isPresent(): true
Info totalCpuDuration().isPresent(): true
Info user().isPresent(): true
Ready to destroy Process with id: 4384
---------------------------
After destroying the process:
---------
Id: 4384
isAlive(): false
isSupportsNormalTermination(): false
Info: [user: Optional[Tutorialspoint\User], startTime: Optional[2020-03-06T10:58:53.210Z], totalTime: Optional[PT0.109375S]]
Info arguments().isPresent(): false
Info command().isPresent(): false
Info totalCpuDuration().isPresent(): true
Info user().isPresent(): true

destroy() vs destroyForcibly()

onExit() - CompletableFuture

processHandle.onExit().thenAccept(ph -> {
    System.out.println("Process " + ph.pid() + " terminated");
});

Process API ให้การจัดการ process แบบ cross-platform ไม่ต้องใช้ JNI หรือ external commands