Java 我需要覆盖属性文件中的值

我的属性文件包含3个属性，我需要覆盖thirdOne的值。如何从java代码中的类路径加载属性文件并覆盖它

我的属性文件位置PackageName->resource->folderName->.propertyFile

属性文件：我需要覆盖“epochromtime”的值：

FILE_PATH=C:\\Users\\pda\\Desktop\\JsonOutput\\DataExtract
epochFilename=C:\\Users\\pda\\Desktop\\JsonOutput\\epochTime.txt
epochFromTime=1545329531862

Java代码：

try {
            Properties config = new Properties();
                config.load(ClassLoader.getSystemResourceAsStream(PROPERTIES_PATH));
                String epochFromTimeChanged= Long.toString(epoch_to2);
                config.setProperty("epochFromTime",epochFromTimeChanged);
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } 

---

这很容易。首先，请将属性文件读取到

属性

。然后更新它，然后保存它。不要忘记关闭资源

public static void updateProperties(File file, Consumer<Properties> consumer) throws IOException {
    Properties properties = new Properties();

    try (Reader reader = new BufferedReader(new FileReader(file))) {
        properties.load(reader);
    }

    consumer.accept(properties);

    try (BufferedWriter writer = new BufferedWriter(new FileWriter(file))) {
        properties.store(writer, "comment");
    }

}

---

应用程序属性

更新前

更新后

使用

Properties.store（）

将更改后的值写回文件：

String PROPERTIES_PATH = "...";
try {
    File f = new File(PROPERTIES_PATH);
    FileInputStream in = new FileInputStream(f);
    Properties config = new Properties();
    config.load(in);

    String epochFromTimeChanged= Long.toString(epoch_to2);
    config.setProperty("epochFromTime",epochFromTimeChanged);

    // get or create the file
    File f = new File(PROPERTIES_PATH);
    OutputStream out = new FileOutputStream(f);
    config.store(out, "My properties file comment");

} catch (FileNotFoundException e1) {
    log.info("{} does not exist", PROPERTIES_PATH);
} catch (IOException e) {
    log.error("Cannot access {}", PROPERTIES_PATH, e);
}

---

你试过什么，什么不起作用？不，它不起作用。你能告诉我如何使用FileOutputStream来实现这一点吗？关于OutputStream的使用有很多例子。我相信你很容易就能找到它们。对于属性，如果您使用外部库，它将被指定用于管理它们。仅仅说“它不工作”对我们没有任何帮助。请查看这篇文章，并发布一个演示您正面临的确切问题的帖子…您只是从文件加载属性，然后更改内存中的值。您的代码不会将任何内容保存到文件中，也没有理由认为这只是奇迹般地发生了。你必须尝试一些东西，而不是说“它不起作用”。

two=two_two
one=one_one

#comment
#Fri Jan 04 18:59:12 MSK 2019
two=two_two_two
one=one_one
three=three_three

String PROPERTIES_PATH = "...";
try {
    File f = new File(PROPERTIES_PATH);
    FileInputStream in = new FileInputStream(f);
    Properties config = new Properties();
    config.load(in);

    String epochFromTimeChanged= Long.toString(epoch_to2);
    config.setProperty("epochFromTime",epochFromTimeChanged);

    // get or create the file
    File f = new File(PROPERTIES_PATH);
    OutputStream out = new FileOutputStream(f);
    config.store(out, "My properties file comment");

} catch (FileNotFoundException e1) {
    log.info("{} does not exist", PROPERTIES_PATH);
} catch (IOException e) {
    log.error("Cannot access {}", PROPERTIES_PATH, e);
}