我们创建了一个资源。utf8文件，包含UTF-8格式的资源，并有一个规则运行如下:

native2ascii -encoding utf8 resources.utf8 resources.properties

注意:在Java <= 8 Java属性文件应该编码在ISO 8859-1!

ISO 8859-1字符编码。 不能直接输入的字符 用这种编码表示可以 使用Unicode转义符编写;只有 允许输入一个“u”字符 转义序列。

Java文档

如果你真的想这样做:看看: Eclipse中的Java属性UTF-8编码——有一些代码示例

因为Java 9:属性文件是用UTF-8编码的，所以应该没有问题/疑问

在Java SE 9中，属性文件以UTF-8编码方式加载。在以前的版本中，ISO-8859-1编码用于加载属性资源包。

(https://docs.oracle.com/javase/9/intl/internationalization -改进- jdk 9. - htm # jsint guid - 9 - dcdb41c a989 - 4220 - 8140 - dbfb844a0fca)

Properties prop = new Properties();
String fileName = "./src/test/resources/predefined.properties";
FileInputStream inputStream = new FileInputStream(fileName);
InputStreamReader reader = new InputStreamReader(inputStream,"UTF-8");

这个问题终于在Java 9中得到了解决: https://docs.oracle.com/javase/9/intl/internationalization-enhancements-jdk-9

属性文件的默认编码现在是UTF-8。

大多数现有属性文件不应受到影响:UTF-8和 ISO-8859-1对ASCII字符有相同的编码 人类可读的非ascii ISO-8859-1编码不是有效的UTF-8。如果一个 检测到无效的UTF-8字节序列，Java运行时 自动重新读取ISO-8859-1中的文件。

看这个:http://docs.oracle.com/javase/6/docs/api/java/util/Properties.html#load(java.io.Reader)

属性接受Reader对象作为参数，您可以从InputStream创建该对象。

在创建时，你可以指定Reader的编码:

InputStreamReader isr = new InputStreamReader(stream, "UTF-8");

然后将这个Reader应用到load方法:

prop.load(isr);

顺便说一句:从.properties文件中获取流:

 InputStream stream = this.class.getClassLoader().getResourceAsStream("a.properties");

顺便说一句:从InputStreamReader获取资源包:

ResourceBundle rb = new PropertyResourceBundle(isr);

希望这能帮助到你!

对于当前(2021-2)Java版本，仍然有旧的ISO-8859-1函数utils.Properties#load。

如果您使用属性。装载时必须使用ISO-8859-1。 如果使用ResourceBundle，那么UTF-8应该没问题。

请允许我引用官方文件。

PropertyResourceBundle

PropertyResourceBundle can be constructed either from an InputStream or a Reader, which represents a property file. Constructing a PropertyResourceBundle instance from an InputStream requires that the input stream be encoded in UTF-8. By default, if a MalformedInputException or an UnmappableCharacterException occurs on reading the input stream, then the PropertyResourceBundle instance resets to the state before the exception, re-reads the input stream in ISO-8859-1, and continues reading. If the system property java.util.PropertyResourceBundle.encoding is set to either "ISO-8859-1" or "UTF-8", the input stream is solely read in that encoding, and throws the exception if it encounters an invalid sequence. If "ISO-8859-1" is specified, characters that cannot be represented in ISO-8859-1 encoding must be represented by Unicode Escapes as defined in section 3.3 of The Java™ Language Specification whereas the other constructor which takes a Reader does not have that limitation. Other encoding values are ignored for this system property. The system property is read and evaluated when initializing this class. Changing or removing the property has no effect after the initialization.

https://docs.oracle.com/en/java/javase/14/docs/api/java.base/java/util/PropertyResourceBundle.html

属性#负载

从输入字节流中读取属性列表(键和元素对)。输入流采用load(Reader)中指定的简单的面向行的格式，并假定使用ISO 8859-1字符编码;即每个字节是一个拉丁字符。非拉丁字符1和某些特殊字符使用Java™语言规范3.3节中定义的Unicode转义符在键和元素中表示。

https://docs.oracle.com/en/java/javase/14/docs/api/java.base/java/util/Properties.html加载(java.io.InputStream)