Examples of org.apache.log4j.joran.spi.Interpreter

org.apache.log4j.joran.spi.Interpreter

Interpreter is Joran's main driving class. It extends SAX {@link org.xml.sax.helpers.DefaultHandler DefaultHandler} which invokes various {@link Action actions} according to predefined patterns.

Patterns are kept in a {@link RuleStore} which is programmed to store andthen later produce the applicable actions for a given pattern.

The pattern corresponding to a top level <a> element is the string "a".

The pattern corresponding to an element <b> embeded within a top level <a> element is the string "a/b".

The pattern corresponding to an <b> and any level of nesting is "*/b. Thus, the * character placed at the beginning of a pattern serves as a wildcard for the level of nesting. Conceptually, this is very similar to the API of commons-digester. Joran offers several small advantages. First and foremost, it offers support for implicit actions which result in a significant leap in flexibility. Second, in our opinion better error reporting capability. Third, it is self-reliant. It does not depend on other APIs, in particular commons-logging which is a big no-no for log4j. Last but not least, joran is quite tiny and is expected to remain so. @author Ceki Gülcuü

    ruleStore.addRule(new Pattern("*/computation/literal"), new LiteralAction());
    ruleStore.addRule(new Pattern("*/computation/add"), new AddAction());
    ruleStore.addRule(new Pattern("*/computation/multiply"), new MultiplyAction());
    
    // Create a new Joran Interpreter and hand it our simple rule store.
    Interpreter ji = new Interpreter(ruleStore);


    // Create a SAX parser
    SAXParserFactory spf = SAXParserFactory.newInstance();
    SAXParser saxParser = spf.newSAXParser();


    // Parse the file given as the application's first argument and
    // set the SAX ContentHandler to the Joran Interpreter we just created.
    saxParser.parse(args[0], ji);
    
    // The file has been parsed and interpreted. We now print any errors that 
    // might have occured.
    List errorList = ji.getExecutionContext().getErrorList();
    if(errorList.size() > 0) {
      System.out.println("The following errors occured:");
      for(int i = 0; i < errorList.size(); i++) {
        System.out.println("\t"+errorList.get(i));
      }

Examples of org.apache.log4j.joran.spi.Interpreter

Related Classes of org.apache.log4j.joran.spi.Interpreter