これは、Javaに変換された@ paul-blairの回答の組み合わせです。これには、paul blairによって指摘されたいくつかのクリーンアップと、@ Edward Campbellと匿名で構成される@pushyのコード内にあると思われるいくつかの誤りが含まれます。
このコードをテストでのみ使用する必要があることを強調することはできません。非常にハックです。しかし、テストで環境設定が必要な場合は、まさにそれが必要でした。
これには、コードが実行されている両方のWindowsで機能するようにする、マイナーなタッチも含まれます
java version "1.8.0_92"
Java(TM) SE Runtime Environment (build 1.8.0_92-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.92-b14, mixed mode)
Centosと同様に
openjdk version "1.8.0_91"
OpenJDK Runtime Environment (build 1.8.0_91-b14)
OpenJDK 64-Bit Server VM (build 25.91-b14, mixed mode)
実装：
/**
* Sets an environment variable FOR THE CURRENT RUN OF THE JVM
* Does not actually modify the system's environment variables,
* but rather only the copy of the variables that java has taken,
* and hence should only be used for testing purposes!
* @param key The Name of the variable to set
* @param value The value of the variable to set
*/
@SuppressWarnings("unchecked")
public static <K,V> void setenv(final String key, final String value) {
try {
/// we obtain the actual environment
final Class<?> processEnvironmentClass = Class.forName("java.lang.ProcessEnvironment");
final Field theEnvironmentField = processEnvironmentClass.getDeclaredField("theEnvironment");
final boolean environmentAccessibility = theEnvironmentField.isAccessible();
theEnvironmentField.setAccessible(true);
final Map<K,V> env = (Map<K, V>) theEnvironmentField.get(null);
if (SystemUtils.IS_OS_WINDOWS) {
// This is all that is needed on windows running java jdk 1.8.0_92
if (value == null) {
env.remove(key);
} else {
env.put((K) key, (V) value);
}
} else {
// This is triggered to work on openjdk 1.8.0_91
// The ProcessEnvironment$Variable is the key of the map
final Class<K> variableClass = (Class<K>) Class.forName("java.lang.ProcessEnvironment$Variable");
final Method convertToVariable = variableClass.getMethod("valueOf", String.class);
final boolean conversionVariableAccessibility = convertToVariable.isAccessible();
convertToVariable.setAccessible(true);
// The ProcessEnvironment$Value is the value fo the map
final Class<V> valueClass = (Class<V>) Class.forName("java.lang.ProcessEnvironment$Value");
final Method convertToValue = valueClass.getMethod("valueOf", String.class);
final boolean conversionValueAccessibility = convertToValue.isAccessible();
convertToValue.setAccessible(true);
if (value == null) {
env.remove(convertToVariable.invoke(null, key));
} else {
// we place the new value inside the map after conversion so as to
// avoid class cast exceptions when rerunning this code
env.put((K) convertToVariable.invoke(null, key), (V) convertToValue.invoke(null, value));
// reset accessibility to what they were
convertToValue.setAccessible(conversionValueAccessibility);
convertToVariable.setAccessible(conversionVariableAccessibility);
}
}
// reset environment accessibility
theEnvironmentField.setAccessible(environmentAccessibility);
// we apply the same to the case insensitive environment
final Field theCaseInsensitiveEnvironmentField = processEnvironmentClass.getDeclaredField("theCaseInsensitiveEnvironment");
final boolean insensitiveAccessibility = theCaseInsensitiveEnvironmentField.isAccessible();
theCaseInsensitiveEnvironmentField.setAccessible(true);
// Not entirely sure if this needs to be casted to ProcessEnvironment$Variable and $Value as well
final Map<String, String> cienv = (Map<String, String>) theCaseInsensitiveEnvironmentField.get(null);
if (value == null) {
// remove if null
cienv.remove(key);
} else {
cienv.put(key, value);
}
theCaseInsensitiveEnvironmentField.setAccessible(insensitiveAccessibility);
} catch (final ClassNotFoundException | NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
throw new IllegalStateException("Failed setting environment variable <"+key+"> to <"+value+">", e);
} catch (final NoSuchFieldException e) {
// we could not find theEnvironment
final Map<String, String> env = System.getenv();
Stream.of(Collections.class.getDeclaredClasses())
// obtain the declared classes of type $UnmodifiableMap
.filter(c1 -> "java.util.Collections$UnmodifiableMap".equals(c1.getName()))
.map(c1 -> {
try {
return c1.getDeclaredField("m");
} catch (final NoSuchFieldException e1) {
throw new IllegalStateException("Failed setting environment variable <"+key+"> to <"+value+"> when locating in-class memory map of environment", e1);
}
})
.forEach(field -> {
try {
final boolean fieldAccessibility = field.isAccessible();
field.setAccessible(true);
// we obtain the environment
final Map<String, String> map = (Map<String, String>) field.get(env);
if (value == null) {
// remove if null
map.remove(key);
} else {
map.put(key, value);
}
// reset accessibility
field.setAccessible(fieldAccessibility);
} catch (final ConcurrentModificationException e1) {
// This may happen if we keep backups of the environment before calling this method
// as the map that we kept as a backup may be picked up inside this block.
// So we simply skip this attempt and continue adjusting the other maps
// To avoid this one should always keep individual keys/value backups not the entire map
LOGGER.info("Attempted to modify source map: "+field.getDeclaringClass()+"#"+field.getName(), e1);
} catch (final IllegalAccessException e1) {
throw new IllegalStateException("Failed setting environment variable <"+key+"> to <"+value+">. Unable to access field!", e1);
}
});
}
LOGGER.info("Set environment variable <"+key+"> to <"+value+">. Sanity Check: "+System.getenv(key));
}