Question

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packagName-> resource-> folderName->。propertyFile

属性文件：我需要覆盖“ epochFromTime”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();
            }

Answer 1

这很容易。首先，将属性文件读取到Properties。然后更新并保存。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");
    }

}

客户端代码如下：

updateProperties(
        new File("application.properties"),
        properties -> {
            properties.setProperty("two", "two_two_two");
            properties.setProperty("three", "three_three");
        });

application.properties

更新前

two=two_two
one=one_one

更新后

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

Answer 2

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);
}

我需要覆盖属性文件中的值

2 个答案: