* ConfigFileReader will read a properly formatted configuration file. * A properly formatted configuration file contains sections followed * by key-value pairs, one on each line. Each section is clearly labelled * with the section name on a separate line, enclosed in square braces [ ]. * Each key is separated from the value by an '=' sign. * *
* An example of a configuration file 'example.ini': * *
* # this is a comment * *
* [section1]
* key1 = value1 # comments begin after '#'
* key2 = value2
* key3 = value3
* [section2]
* key4 = value4
* [section3]
* key5 = value5
*
* If a configuration file contains duplicate keys, the value found * will be the first defined key. Subsequent overrides will not be * valid. *
* @author hao lieu (hlieu@blueprint.org)
*/
public class ConfigFileReader
{
/**
* Name of the configuration file.
*/
private String file;
/**
* Creates a configuration reader attached to filename
* @param filename the file to read
*/
public ConfigFileReader(String filename)
{
this.file = filename;
}
/**
* Moves buffered reader into section.
* @param section the section to move to.
* @return true if successful, else false.
* @throws IOException
*/
private boolean gotoSection(String section, BufferedReader in) throws IOException
{
String input;
while((input = in.readLine()) != null)
{
/* trim the white spaces in front and back */
input = input.trim();
try { /* in case of empty lines ... */
input = input.substring(1, input.length() - 1);
} catch (StringIndexOutOfBoundsException exception) {
continue; /* ... just skip over them */
}
if(input.equals(section)) return true;
}
return false;
}
/**
* Returns the value associated with key, or null.
* @param key the key to look for and retrieve the value.
* @return the value associated with key, or null if not found
* @throws IOException
*/
private String getKey(String key, BufferedReader in) throws IOException
{
String input; int i;
/* we're reached the correct section, now we read in
until we hit the correct key. */
while((input = in.readLine()) != null)
{
input = input.trim();
if(input.length() == 0){
/* empty line so we can skip it */
continue;
}
if(input.charAt(0) == '#'){
/* comment, so we can skip this */
continue;
}
if(input.matches("\\[.*\\]")){
/* new section encountered, so our key was not
defined where we thought it was, so done
searching through our section. */
return null;
}
if(input.matches(key)){ /* found our key */
/* remove everything trailing after the comment indicator (#)
if no #, then remove nothing. */
input = (input.indexOf('#') < 0 ? input : input.substring(0, input.indexOf("#")));
if((i = input.indexOf('=')) < 0)
{
/* '= value' is not set, so keep going */
continue;
}else{
/* '= value' is set, so we try to grab it ... */
try {
input = input.substring(i+1, input.length());
} catch (IndexOutOfBoundsException e){
/* ... value not set so keep going, hopefully it is set later on. */
continue;
} /* end try */
/* heres our value, so we get rid of front and back white space
and return it. */
return input.trim();
} /* end else */
} /* end if(matches) */
} /* end while(input) */
/* if get here, we never found our key match */
return null;
}
/**
* Retrieves the value matching key in section.
* If the section or key in section is not found, returns null.
*
* @param section the section in the configuration file.
* Sections are enclosed in [ ] in the configuration file.
* @param key the key that identifies the value being retrieved.
* @return the value associated with key in section
* @throws IOException
* @throws FileNotFoundException
*/
public String get(String section, String key)
throws IOException, FileNotFoundException
{
BufferedReader in = new BufferedReader(new FileReader(this.file));
key = ".*".concat(key).concat(".*=.*");;
if(!this.gotoSection(section, in))
{ /* section not found */
return null;
}
String value = this.getKey(key, in);
in.close();
return value;
}
}