📅 最后修改于: 2020-10-14 00:42:52 🧑 作者: Mango
Java改进了Java 9版本的流程API，该API有助于管理和控制操作系统流程。
在早期版本中，使用Java编程来管理和控制操作系统进程很复杂。现在，添加了新的类和接口来执行此任务。
下表中将新方法添加到java.lang.Process类。
| Modifier and Type | Method | Description |
|---|---|---|
| boolean | supportsNormalTermination() | It returns true if the implementation of destroy() is to normally terminate the process, else returns false. |
| ProcessHandle | toHandle() | It returns a ProcessHandle for the Process. |
| long | pid() | It returns the native process ID of the process. |
| Stream |
children() | It returns a snapshot of the direct children of the process. |
| Stream |
descendants() | It returns a snapshot of the descendants of the process. |
| ProcessHandle.Info | info() | It returns a snapshot of information about the process. |
| CompletableFuture |
onExit() | It returns a CompletableFuture |
添加了新的接口ProcessHandle和ProcessHandle.Info。
ProcessHandle帮助处理和控制过程。我们可以监控流程，列出其子级，获取信息等。
此接口包含静态工厂方法，这些方法返回基于值，不可变且线程安全的实例。
public interface ProcessHandle extends Comparable
此接口包含以下方法。
| Modifier and Type | Method | Description |
|---|---|---|
| static Stream |
allProcesses() | It returns a snapshot of all processes visible to the current process. |
| Stream |
children() | It returns a snapshot of the current direct children of the process. |
| int | compareTo(ProcessHandle other) | It compares this ProcessHandle with the specified ProcessHandle for order. |
| static ProcessHandle | current() | It returns a ProcessHandle for the current process. |
| Stream |
descendants() | It returns a snapshot of the descendants of the process. |
| boolean | destroy() | It requests the process to be killed. |
| boolean | destroyForcibly() | It requests the process to be killed forcibly. |
| boolean | equals(Object other) | It returns true if other object is non-null, is of the same implementation, and represents the same system process; otherwise it It returns false. |
| int | hashCode() | It returns a hash code value for this ProcessHandle. |
| ProcessHandle.Info | info() | It returns a snapshot of information about the process. |
| boolean | isAlive() | It tests whether the process represented by this ProcessHandle is alive. |
| static Optional |
of(long pid) | It returns an Optional |
| CompletableFuture |
onExit() | It returns a CompletableFuture |
| Optional |
parent() | It returns an Optional |
| long | pid() | It returns the native process ID of the process. |
| boolean | supportsNormalTermination() | It returns true if the implementation of destroy() normally terminates the process. |
它被添加到Java 9中，并用于提供有关该过程的信息。它是ProcessHandle接口的嵌套接口。
Java ProcessHandle.Info接口签名
public static interface ProcessHandle.Info
| Modifier and Type | Method | Description |
|---|---|---|
| Optional |
arguments() | It returns an array of Strings of the arguments of the process. |
| Optional |
command() | It returns the executable pathname of the process. |
| Optional |
commandLine() | It returns the command line of the process. |
| Optional |
startInstant() | It returns the start time of the process. |
| Optional |
totalCpuDuration() | It returns the total cputime accumulated of the process. |
| Optional |
user() | It returns the user of the process. |
public class ProcessApiExample {
public static void main(String[] args) {
ProcessHandle currentProcess = ProcessHandle.current(); // Current processhandle
System.out.println("Process Id: "+currentProcess.pid()); // Process id
System.out.println("Direct children: "+ currentProcess.children()); // Direct children of the process
System.out.println("Class name: "+currentProcess.getClass()); // Class name
System.out.println("All processes: "+ProcessHandle.allProcesses()); // All current processes
System.out.println("Process info: "+currentProcess.info()); // Process info
System.out.println("Is process alive: "+currentProcess.isAlive());
System.out.println("Process's parent "+currentProcess.parent()); // Parent of the process
}
}
输出：
Process Id: 9111
Direct children: java.util.stream.ReferencePipeline$2@6adca536
Class name: class java.lang.ProcessHandleImpl
All processes: java.util.stream.IntPipeline$1@28f67ac7
Process info: [user: Optional[javatpoint],
cmd: /usr/lib/jvm/java-9-oracle/bin/java, args: [-Dfile.encoding=UTF-8,
-classpath, /home/javatpoint/irfan/java 9/java 9 programms/Java9Features/bin,
ProcessApiExample], startTime: Optional[2017-11-18T06:30:57.940Z], totalTime: Optional[PT0.25S]]
Is process alive: true
Process's parent: Optional[7509]