如何将所有 Java 系统属性转换为 HashMap<String,String>？
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How to convert all Java System Properties to HashMap<String,String>?
提问by
This nice articleshows us how to print all the current system properties to STDOUT, but I need to convert everything that's in System.getProperties()to a HashMap<String,String>.
这篇不错的文章向我们展示了如何将所有当前系统属性打印到 STDOUT，但我需要将所有内容转换System.getProperties()为HashMap<String,String>.
Hence if there is a system property called "baconator", with a value of "yes!", that I set with System.setProperty("baconator, "yes!"), then I want the HashMapto have a key of baconatorand a respective value of yes!, etc. Same idea for allsystem properties.
因此，如果有一个名为“baconator”的系统属性，其值为“yes！”，我用 设置System.setProperty("baconator, "yes!")，那么我希望HashMap有一个键baconator和一个相应的值yes!，等等。所有系统属性的想法都是一样的。
I tried this:
我试过这个：
Properties systemProperties = System.getProperties();
for(String propertyName : systemProperties.keySet())
;
But then get an error:
但随后得到一个错误：
Type mismatch: cannot convert from element type Object to String
类型不匹配：无法从元素类型对象转换为字符串
So then I tried:
然后我尝试了：
Properties systemProperties = System.getProperties();
for(String propertyName : (String)systemProperties.keySet())
;
And am getting this error:
并且收到此错误：
Can only iterate over an array or an instance of java.lang.Iterable
只能迭代数组或 java.lang.Iterable 的实例
Any ideas?
有任何想法吗？
采纳答案by Luiggi Mendoza
I did a sample test using Map.Entry
我做了一个样本测试使用 Map.Entry
Properties systemProperties = System.getProperties();
for(Entry<Object, Object> x : systemProperties.entrySet()) {
System.out.println(x.getKey() + " " + x.getValue());
}
For your case, you can use this to store it in your Map<String, String>:
对于您的情况，您可以使用它来将其存储在您的Map<String, String>：
Map<String, String> mapProperties = new HashMap<String, String>();
Properties systemProperties = System.getProperties();
for(Entry<Object, Object> x : systemProperties.entrySet()) {
mapProperties.put((String)x.getKey(), (String)x.getValue());
}
for(Entry<String, String> x : mapProperties.entrySet()) {
System.out.println(x.getKey() + " " + x.getValue());
}
回答by rgettman
Loop over the Set<String>(which is Iterable) that is returned by the stringPropertyNames()method. When processing each property name, use getPropertyto get the property value. Then you have the information needed to putyour property values into your HashMap.
循环遍历该方法返回的Set<String>（即Iterable）stringPropertyNames()。处理每个属性名称时，使用getProperty来获取属性值。然后您将put您的属性值所需的信息放入您的HashMap.
回答by Agustí Sánchez
Since Java 8, you can type this -rather long- one-liner:
从 Java 8 开始，你可以输入这个——相当长的——单行：
Map<String, String> map = System.getProperties().entrySet().stream()
.collect(Collectors.toMap(e -> (String) e.getKey(), e -> (String) e.getValue()));
回答by darijan
This does work
这确实有效
Properties properties= System.getProperties();
for (Object key : properties.keySet()) {
Object value= properties.get(key);
String stringKey= (String)key;
String stringValue= (String)value;
//just put it in a map: map.put(stringKey, stringValue);
System.out.println(stringKey + " " + stringValue);
}
回答by JHS
Either you can use the entrySet()method from Propertiesto get an Entrytype from Propertieswhich is Iterableor you could use the stringPropertyNames()method from the Propertiesclass to get a Setof keys in this property list. The use the getPropertymethod to get the property value.
您可以使用entrySet()from 方法Properties获取is的Entry类型，Properties也Iterable可以使用类中的stringPropertyNames()方法Properties获取Set此属性列表中的a键。使用getProperty方法获取属性值。
