read/write 属性文件如何用冒号“:”而不是等于“=”分隔键和值

Question

我有包含 key:value 列表的属性文件，如下所示：

key1 : value1
key2 : value2

如何使用属性 class 读写此文件？可不可以？

Answer 1

是的。你考虑过尝试一下吗？或咨询 documentation?

The key contains all of the characters in the line starting with the first non-white space character and up to, but not including, the first unescaped '=', ':', or white space character other than a line terminator. All of these key termination characters may be included in the key by escaping them with a preceding backslash character; for example,

Answer 2

硬核解决方案。

将此文件作为文本文件读入字符串。 See example.
将:替换为=。

从字符串解析属性，参见Parsing string as properties

public Properties parsePropertiesString(String s) {
    final Properties p = new Properties();
    p.load(new StringReader(s));
    return p;
}

如果要将属性写入文件，请以相反的顺序执行相同的操作。将属性写入字符串，将=替换为:，并将字符串写入文件。

Answer 3

您可以使用以下代码读取属性文件。请注意“:”与“=”的作用相同。

try (InputStream in = new FileInputStream("filename.propeties")) {
    Properties prop = new Properties();
    prop.load(in);


    for (String key: prop.stringPropertyNames()) {
        String value = prop.getProperty(key);
        System.out.println(key+ "=" + value);
    }
} catch (IOException e) {
    e.printStackTrace();
}

Answer 4

我查看 java 属性 class（在 jdk 中），发现 java 使用常量 '=' 通过以下方法保存属性文件：

private void store0(BufferedWriter bw, String comments, boolean escUnicode)
    throws IOException
{
    if (comments != null) {
        writeComments(bw, comments);
    }
    bw.write("#" + new Date().toString());
    bw.newLine();
    synchronized (this) {
        for (Enumeration<?> e = keys(); e.hasMoreElements();) {
            String key = (String)e.nextElement();
            String val = (String)get(key);
            key = saveConvert(key, true, escUnicode);
            /* No need to escape embedded and trailing spaces for value, hence
             * pass false to flag.
             */
            val = saveConvert(val, false, escUnicode);
            bw.write(key + "=" + val);
            bw.newLine();
        }
    }
    bw.flush();
}

所以，无法处理我的属性文件。但是对于 erad/write 我的属性文件，我发现这个文件是一个 yaml 格式，我们可以通过这种方法轻松读取文件：

public Map read(String path) {
    ObjectMapper mapper = new ObjectMapper(new YAMLFactory());
    try {
        File file = new File(path);
        Map map = mapper.readValue(file, Map.class);
        return map;
    } catch (Exception e) {
        logger.error("Error during read Yml file {}", path, e);
    }
    return new HashMap();
}

并通过以下方法更新文件：

public boolean update(String path, Map content) {
    try {
        YAMLFactory yamlFactory = new YAMLFactory();
        yamlFactory.enable(YAMLGenerator.Feature.MINIMIZE_QUOTES);

        File file = new File(path);
        ObjectMapper mapper = new ObjectMapper(yamlFactory);
        ObjectWriter writer = mapper.writerWithDefaultPrettyPrinter();
        writer.writeValue(file, content);
        return true;
    } catch (Exception e) {
        logger.error("Error during save Yml file {}", path, e);
    }
    return false;
}

重要的是我使用以下代码来防止对值使用双引号：

yamlFactory.enable(YAMLGenerator.Feature.MINIMIZE_QUOTES);

read/write 属性文件如何用冒号“:”而不是等于“=”分隔键和值

how read/write properties file which seperated key and value with colon ':' instead of equal '='

java

properties-file