Class Logging

test/Logging.java:6–150

import java.util.logging.Logger;

public class Logging {
  private static final Logger log = Logger.getLogger("Logging");

  private static class MyHandler extends Handler {
    private static final int NAME_WIDTH = 18;
    private static final int METHOD_WIDTH = 20;
    private static final int LEVEL_WIDTH = 8;

    public Object clone() { return this; }
    public void close() { }
    public void flush() { }

    private void maybeLogThrown(StringBuilder sb, Throwable t) {
      if (t != null) {
        sb.append("\nCaused by: ");
        sb.append(t.getClass().getName());
        sb.append(": ");
        sb.append(t.getMessage());
        sb.append('\n');

        for (StackTraceElement elt : t.getStackTrace()) {
          sb.append('\t');
          sb.append(elt.getClassName());
          sb.append('.');
          sb.append(elt.getMethodName());
          sb.append('(');
          sb.append(elt.getFileName());
          sb.append(':');
          sb.append(elt.getLineNumber());
          sb.append(')');
          sb.append('\n');
        }
        maybeLogThrown(sb, t.getCause());
      }
    }

    private void indent(StringBuilder sb, int amount) {
      do {
        sb.append(' ');
      } while (--amount > 0);
    }

    public void publish(LogRecord r) {
      StringBuilder sb = new StringBuilder();
      sb.append(r.getLoggerName());
      indent(sb, NAME_WIDTH - r.getLoggerName().length());
      String methodName = r.getSourceMethodName();
      if (methodName == null) {
        methodName = "<unknown>";
      }
      sb.append(methodName);
      indent(sb, METHOD_WIDTH - methodName.length());
      sb.append(r.getLevel().getName());
      indent(sb, LEVEL_WIDTH - r.getLevel().getName().length());
      sb.append(r.getMessage());
      maybeLogThrown(sb, r.getThrown());
      System.out.println(sb.toString());
    }