如何在Java中仅加载一次属性？

Question

I have loaded property file in java.

public String getproperties(String property)
    InputStream inputStream = new ClassPathResource("test.properties").getInputStream();
            Properties testProperties = new Properties();
            testProperties.load(inputStream);
            inputStream.close();
            return testProperties.getProperty(propertyType);

}

Its loaded successfully.The problem is every time property file loaded instead of loading only once. How to achieve this?

Answer 1

Store the Properties object as a field outside the method, initially null, and only create it on first call:

private Properties testProperties = null;

public String getproperties(String property)
    if (testProperties == null) {
        InputStream inputStream = new ClassPathResource("test.properties").getInputStream();
        testProperties = new Properties();
        testProperties.load(inputStream);
        inputStream.close();
    }
    return testProperties.getProperty(propertyType);
}

Answer 2

You can easily cache the properties by doing something like this:

class PropertyContainer {
    private static Properties properties;
    public static synchronized Properties getProperties() {
        if (properties != null) { return properties; }
        InputStream inputStream = new ClassPathResource("test.properties").getInputStream();
        properties = new Properties();
        properties.load(inputStream);
        inputStream.close();
    }
}

Your old getproperties method would then be something like this:

return PropertyContainer.getProperties().getProperty(propertyType);

This of course assumes that you only need one property file.

Answer 3

只需创建类字段的Properties属性即可：）并在其中保存一次加载的值。

Answer 4

I usually wrap this into a private method, storing the object into a private field:

private Properties _testProperties;
private Properties properties() {
  if (_testProperties == null) {
        InputStream inputStream = new ClassPathResource("test.properties").getInputStream();
       _testProperties = new Properties();
        inputStream.close();
       _testProperties.load(inputStream);
  }
  return _testProperties ;
}

public String getproperties(String property) {
   return properties().getProperty(property);
}