Java –すべての環境変数を表示する方法
Javaでは、System.getenv()
を使用して、すべての環境変数を含むMap
を返すことができます。
Mapenv = System.getenv(); env.forEach((k, v) -> System.out.println(k + ":" + v));
1. 例
DisplayApp.java
package com.example.display; import java.util.Map; public class DisplayApp { public static void main(String[] args) { Mapenv = System.getenv(); // Java 8 //env.forEach((k, v) -> System.out.println(k + ":" + v)); // Classic way to loop a map for (Map.Entry entry : env.entrySet()) { System.out.println(entry.getKey() + " : " + entry.getValue()); } } }
出力
USERDOMAIN_ROAMINGPROFILE : DESKTOP-20APO9O PROCESSOR_LEVEL : 6 SESSIONNAME : Console ALLUSERSPROFILE : C:\ProgramData PROCESSOR_ARCHITECTURE : AMD64 SystemDrive : C: MAVEN_HOME : C:\opt\apache-maven-3.5.3 NGINX : C:\opt\nginx-1.12.2 USERNAME : example GPU_USE_SYNC_OBJECTS : 1 ProgramFiles(x86) : C:\Program Files (x86) GPU_MAX_ALLOC_PERCENT : 100 PATHEXT : .COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC DriverData : C:\Windows\System32\Drivers\DriverData ProgramData : C:\ProgramData ProgramW6432 : C:\Program Files HOMEPATH : \Users\example PROCESSOR_IDENTIFIER : Intel64 Family 6 Model 158 Stepping 9, GenuineIntel ProgramFiles : C:\Program Files PUBLIC : C:\Users\Public windir : C:\WINDOWS =:: : ::\ GPU_MAX_HEAP_SIZE : 100 LOCALAPPDATA : C:\Users\example\AppData\Local GPU_SINGLE_ALLOC_PERCENT : 100 GPU_FORCE_64BIT_PTR : 0 //...
2. ソート
すべての環境変数をアルファベット順に表示するJava 8の例。
DisplayApp.java
package com.example.display; package com.example.password; import java.util.LinkedHashMap; import java.util.Map; import java.util.stream.Collectors; public class DisplayApp { public static void main(String[] args) { Mapenv = System.getenv(); LinkedHashMap collect = env.entrySet().stream() .sorted(Map.Entry.comparingByKey()) .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (oldValue, newValue) -> oldValue, LinkedHashMap::new)); collect.forEach((k, v) -> System.out.println(k + ":" + v)); } }
出力
ALLUSERSPROFILE:C:\ProgramData APPDATA:C:\Users\example\AppData\Roaming COMPUTERNAME:DESKTOP-20APO9O ComSpec:C:\WINDOWS\system32\cmd.exe CommonProgramFiles:C:\Program Files\Common Files CommonProgramFiles(x86):C:\Program Files (x86)\Common Files CommonProgramW6432:C:\Program Files\Common Files DriverData:C:\Windows\System32\Drivers\DriverData GPU_FORCE_64BIT_PTR:0 GPU_MAX_ALLOC_PERCENT:100 GPU_MAX_HEAP_SIZE:100 GPU_SINGLE_ALLOC_PERCENT:100 GPU_USE_SYNC_OBJECTS:1 GRADLE_HOME:C:\opt\gradle-4.7 HOMEDRIVE:C: HOMEPATH:\Users\example JAVA_HOME:C:\opt\Java\jdk-10 LOCALAPPDATA:C:\Users\example\AppData\Local LOGONSERVER:\\DESKTOP-20APO9O MAVEN_HOME:C:\opt\apache-maven-3.5.3 MONGODB_HOME:C:\Program Files\MongoDB\Server\3.6 NGINX:C:\opt\nginx-1.12.2 NUMBER_OF_PROCESSORS:8 OS:Windows_NT OneDrive:C:\Users\example\OneDrive PATHEXT:.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC PHP:C:\opt\php-7.2.0 PROCESSOR_ARCHITECTURE:AMD64 PROCESSOR_IDENTIFIER:Intel64 Family 6 Model 158 Stepping 9, GenuineIntel PROCESSOR_LEVEL:6 PROCESSOR_REVISION:9e09 //...