Java 简明教程
Java - Process API Improvements
在 Java 9 中，负责控制和管理操作系统进程的 Process API 已得到极大改进。ProcessHandle 类现在提供进程的本机进程 ID、启动时间、累积的 CPU 时间、参数、命令、用户、父进程和后代。ProcessHandle 类还提供用于检查进程的活跃状态和销毁进程的方法。它有 onExit 方法，CompletableFuture 类可以在进程退出时异步执行动作。
Spawning a new Process Example
在此示例中，我们为记事本创建了一个新的 Process，并使用 ProcessBuilder 启动了该 Process。使用 ProcessHandle.Info 接口，我们正在获取新生成的进程的进程信息。
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));
}
}Getting Current Process Information Example
在此示例中，我们使用 ProcessHandle.current() 方法获取了当前进程。然后使用 ProcessHandle.Info 接口，我们正在获取当前进程的进程信息。
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));
}
}Getting Child Processes Example
在此示例中，我们使用 ProcessHandle.current().children() 方法获取当前进程的子进程。然后使用 ProcessHandle.Info 接口获取子进程的进程信息。
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));
}
);
}
}Output
你将看到类似的输出。
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)