Java - 程序API改進

在Java 9中，負責控制和管理作業系統程序的Process API得到了相當大的改進。ProcessHandle類現在提供了程序的原生程序ID、啟動時間、累積CPU時間、引數、命令、使用者、父程序和子程序。ProcessHandle類還提供方法來檢查程序的活動狀態和銷燬程序。它具有onExit方法，CompletableFuture類可以在程序退出時非同步執行操作。

生成新程序示例

在這個例子中，我們為記事本建立了一個新的程序，並使用ProcessBuilder啟動它。使用ProcessHandle.Info介面，我們獲取了新生成的程序的程序資訊。

package com.tutorialspoint;

import java.time.ZoneId;
import java.util.stream.Stream;
import java.util.stream.Collectors;
import java.io.IOException;

public class Tester {
   public static void main(String[] args) throws IOException {
      ProcessBuilder pb = new ProcessBuilder("notepad.exe");
      String np = "Not Present";
      Process p = pb.start();
      ProcessHandle.Info info = p.info();
      System.out.printf("Process ID : %s%n", p.pid());
      System.out.printf("Command name : %s%n", info.command().orElse(np));
      System.out.printf("Command line : %s%n", info.commandLine().orElse(np));

      System.out.printf("Start time: %s%n",
         info.startInstant().map(i -> i.atZone(ZoneId.systemDefault())
         .toLocalDateTime().toString()).orElse(np));

      System.out.printf("Arguments : %s%n",
         info.arguments().map(a -> Stream.of(a).collect(
         Collectors.joining(" "))).orElse(np));

      System.out.printf("User : %s%n", info.user().orElse(np));
   } 
}

輸出

您將看到類似的輸出。

Process ID : 5580
Command name : C:\Program Files\WindowsApps\Microsoft.WindowsNotepad_11.2401.26.0_x64__8wekyb3d8bbwe\Notepad\Notepad.exe
Command line : Not Present
Start time: 2024-04-02T17:07:14.305
Arguments : Not Present
User : DESKTOP\Tutorialspoint

獲取當前程序資訊示例

在這個例子中，我們使用ProcessHandle.current()方法獲取當前程序。然後使用ProcessHandle.Info介面，我們獲取當前程序的程序資訊。

package com.tutorialspoint;

import java.time.ZoneId;
import java.util.stream.Stream;
import java.util.stream.Collectors;
import java.io.IOException;

public class Tester {
   public static void main(String[] args) throws IOException {
      String np = "Not Present";
      ProcessHandle currentProcess = ProcessHandle.current();
      ProcessHandle.Info info = currentProcess.info();
      System.out.printf("Process ID : %s%n", currentProcess.pid());
      System.out.printf("Command name : %s%n", info.command().orElse(np));
      System.out.printf("Command line : %s%n", info.commandLine().orElse(np));

      System.out.printf("Start time: %s%n",
         info.startInstant().map(i -> i.atZone(ZoneId.systemDefault())
         .toLocalDateTime().toString()).orElse(np));

      System.out.printf("Arguments : %s%n",
         info.arguments().map(a -> Stream.of(a).collect(
         Collectors.joining(" "))).orElse(np));

      System.out.printf("User : %s%n", info.user().orElse(np));
   } 
}

輸出

您將看到類似的輸出。

Process ID : 5352
Command name : C:\Program Files\Java\jdk-21\bin\javaw.exe
Command line : Not Present
Start time: 2024-04-02T17:09:17.902
Arguments : Not Present
User : DESKTOP-DTHL8BI\Tutorialspoint

獲取子程序示例

在這個例子中，我們使用ProcessHandle.current().children()方法獲取當前程序的子程序。然後使用ProcessHandle.Info介面，我們獲取子程序的程序資訊。

package com.tutorialspoint;

import java.io.IOException;
import java.util.stream.Stream;

public class Tester {
   public static void main(String[] args) throws IOException {
      for (int i = 0; i < 3; i++) {
         ProcessBuilder processBuilder
            = new ProcessBuilder("java.exe", "-version");
         processBuilder.inheritIO().start();
      }
      Stream<ProcessHandle> childProcesses = ProcessHandle.current().children();
      String np = "Not Present";
      childProcesses.filter(ProcessHandle::isAlive).forEach(
         childProcess ->{
            System.out.printf("Process ID : %s%n", childProcess.pid());
            System.out.printf("Command name : %s%n", childProcess.info().command().orElse(np));
            System.out.printf("Command line : %s%n", childProcess.info().commandLine().orElse(np));
         }
      );
   } 
}

輸出

您將看到類似的輸出。

Process ID : 5420
Command name : C:\Program Files\Java\jdk-21\bin\java.exe
Command line : Not Present
Process ID : 15796
Command name : C:\Program Files\Java\jdk-21\bin\java.exe
Command line : Not Present
Process ID : 14180
Command name : C:\Program Files\Java\jdk-21\bin\java.exe
Command line : Not Present
java version "21.0.2" 2024-01-16 LTS
Java(TM) SE Runtime Environment (build 21.0.2+13-LTS-58)
Java HotSpot(TM) 64-Bit Server VM (build 21.0.2+13-LTS-58, mixed mode, sharing)
java version "21.0.2" 2024-01-16 LTS
Java(TM) SE Runtime Environment (build 21.0.2+13-LTS-58)
Java HotSpot(TM) 64-Bit Server VM (build 21.0.2+13-LTS-58, mixed mode, sharing)
java version "21.0.2" 2024-01-16 LTS
Java(TM) SE Runtime Environment (build 21.0.2+13-LTS-58)
Java HotSpot(TM) 64-Bit Server VM (build 21.0.2+13-LTS-58, mixed mode, sharing)