since: 1.2.15 -

 public LocationInfo(Throwable t,
    String fqnOfCallingClass) 
{
   
    try {
      inVisualAge = Class.forName("com.ibm.uvm.tools.DebugSupport") != null;
      LogLog.debug("Detected IBM VisualAge environment.");
    } catch(Throwable e) {
      // nothing to do
    }
      if(t == null || fqnOfCallingClass == null)
	return;
      String s;
      // Protect against multiple access to sw.
      synchronized(sw) {
	t.printStackTrace(pw);
	s = sw.toString();
	sw.getBuffer().setLength(0);
      }
      //System.out.println("s is ["+s+"].");
      int ibegin, iend;
      // Given the current structure of the package, the line
      // containing "org.apache.log4j.Category." should be printed just
      // before the caller.
      // This method of searching may not be fastest but it's safer
      // than counting the stack depth which is not guaranteed to be
      // constant across JVM implementations.
      ibegin = s.lastIndexOf(fqnOfCallingClass);
      if(ibegin == -1)
	return;
      ibegin = s.indexOf(Layout.LINE_SEP, ibegin);
      if(ibegin == -1)
	return;
      ibegin+= Layout.LINE_SEP_LEN;
      // determine end of line
      iend = s.indexOf(Layout.LINE_SEP, ibegin);
      if(iend == -1)
	return;
      // VA has a different stack trace format which doesn't
      // need to skip the inital 'at'
      if(!inVisualAge) {
	// back up to first blank character
	ibegin = s.lastIndexOf("at ", iend);
	if(ibegin == -1)
	  return;
	// Add 3 to skip "at ";
	ibegin += 3;
      }
      // everything between is the requested stack item
      this.fullInfo = s.substring(ibegin, iend);
}

Instantiate location information based on a Throwable. We expect the Throwable t, to be in the format

java.lang.Throwable
...
at org.apache.log4j.PatternLayout.format(PatternLayout.java:413)
at org.apache.log4j.FileAppender.doAppend(FileAppender.java:183)
at org.apache.log4j.Category.callAppenders(Category.java:131)
at org.apache.log4j.Category.log(Category.java:512)
at callers.fully.qualified.className.methodName(FileName.java:74)
...

However, we can also deal with JIT compilers that "lose" the location information, especially between the parentheses.

 public LocationInfo(String file,
    String classname,
    String method,
    String line) 
{
      this.fileName = file;
      this.className = classname;
      this.methodName = method;
      this.lineNumber = line;
      StringBuffer buf = new StringBuffer();
	  appendFragment(buf, classname);
	  buf.append(".");
	  appendFragment(buf, method);
	  buf.append("(");
	  appendFragment(buf, file);
	  buf.append(":");
	  appendFragment(buf, line);
	  buf.append(")");
	  this.fullInfo = buf.toString();
}

Create new instance.

Parameters:

file - source file name

classname - class name

method - method

line - source line number

since: 1.2.15 -

 public String getClassName() 
{
      if(fullInfo == null) return NA;
      if(className == null) {
	// Starting the search from '(' is safer because there is
	// potentially a dot between the parentheses.
	int iend = fullInfo.lastIndexOf('(");
	if(iend == -1)
	  className = NA;
	else {
	  iend =fullInfo.lastIndexOf('.", iend);
	  // This is because a stack trace in VisualAge looks like:
          //java.lang.RuntimeException
	  //  java.lang.Throwable()
	  //  java.lang.Exception()
	  //  java.lang.RuntimeException()
	  //  void test.test.B.print()
	  //  void test.test.A.printIndirect()
	  //  void test.test.Run.main(java.lang.String [])
          int ibegin = 0;
	  if (inVisualAge) {
	    ibegin = fullInfo.lastIndexOf(' ", iend)+1;
          }
	  if(iend == -1)
	    className = NA;
	  else
	    className = this.fullInfo.substring(ibegin, iend);
	}
      }
      return className;
}

Return the fully qualified class name of the caller making the logging request.

 public String getFileName() 
{
      if(fullInfo == null) return NA;
      if(fileName == null) {
	int iend = fullInfo.lastIndexOf(':");
	if(iend == -1)
	  fileName = NA;
	else {
	  int ibegin = fullInfo.lastIndexOf('(", iend - 1);
	  fileName = this.fullInfo.substring(ibegin + 1, iend);
	}
      }
      return fileName;
}

Return the file name of the caller.

This information is not always available.

 public String getLineNumber() 
{
      if(fullInfo == null) return NA;
      if(lineNumber == null) {
	int iend = fullInfo.lastIndexOf(')");
	int ibegin = fullInfo.lastIndexOf(':", iend -1);
	if(ibegin == -1)
	  lineNumber = NA;
	else
	  lineNumber = this.fullInfo.substring(ibegin + 1, iend);
      }
      return lineNumber;
}

Returns the line number of the caller.

This information is not always available.

 public String getMethodName() 
{
      if(fullInfo == null) return NA;
      if(methodName == null) {
	int iend = fullInfo.lastIndexOf('(");
	int ibegin = fullInfo.lastIndexOf('.", iend);
	if(ibegin == -1)
	  methodName = NA;
	else
	  methodName = this.fullInfo.substring(ibegin + 1, iend);
      }
      return methodName;
}

Returns the method name of the caller.