Apache Commons Configuration : read a .properties file and rewrite it with no change

Question

Since I do not know of a better solution, I am currently writing small Java classes to process .properties file to merge them, remove duplicate properties, override properties, etc. (I need to process many files and a huge number of properties).

org.apache.commons.configuration.PropertiesConfiguration works great for reading a properties file (using org.apache.commons.configuration.AbstractFileConfiguration.load(InputStream, String), however if I rewrite the file using org.apache.commons.configuration.AbstractFileConfiguration.save(File), I have two problems:

1. the original layout and comments are lost. I am going to try the PropertiesConfigurationLayout, which is supposed to help here (see How to overwrite one property in .properties without overwriting the whole file?) and post the results
2. the properties are slightly modified. Accents é and è are rewritten as unicode characters (\u00E9), which I do not want. Afaik .properties files are generally ISO-8859-1 (and I think mine are), so escaping shouldn't be necessary. Specifying the encoding when calling org.apache.commons.configuration.AbstractFileConfiguration.load(InputStream, String) does not make a difference, because when it is not specified, the same encoding is used by default anyway (private static final String DEFAULT_ENCODING = "ISO-8859-1";). What could I do about that ?

Answer 1

做一些测试我认为你可以使用CombinedConfiguration加OverrideCombiner做你想做的事。基本上，属性将自动合并，布局的技巧是从一个加载的文件中获取布局：

CombinedConfiguration props = new CombinedConfiguration();

final PropertiesConfiguration defaultsProps = new PropertiesConfiguration(new File("/tmp/default.properties"));
final PropertiesConfiguration customProps = new PropertiesConfiguration(new File("/tmp/custom.properties"));
props.setNodeCombiner(new OverrideCombiner());
props.addConfiguration(customProps); //first should be loaded the override values
props.addConfiguration(defaultsProps); // last your 'default' values

PropertiesConfiguration finalFile = new PropertiesConfiguration();   
finalFile.append(props);
PropertiesConfigurationLayout layout = new PropertiesConfigurationLayout(finalFile, defaultsProps.getLayout()); //here we copy the layout from the 'base file'
layout.save(new FileWriter(new File("/tmp/app.properties")));

编码问题我不知道是否可以找到解决方案。