SimpleMonitorRenderer.java

package com.orbitz.monitoring.lib.renderer;

import com.orbitz.monitoring.api.Monitor;

import org.apache.commons.lang.builder.ToStringBuilder;
import org.apache.commons.lang.builder.ToStringStyle;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.Iterator;
import java.util.Map;
import java.util.TreeMap;

/**
 * A simple renderer that renders a monitor with each attribute on a separate line.
 * <p>
 * Example:<br>
 * 
 * <pre>
 * com.orbitz.monitoring.api.monitor.TransactionMonitor
 *   -> arguments = {blah,java.lang.Object@93b022,12345}
 *   -> createdAt = Fri Nov 28 15:09:37 EST 2008
 *   -> endTime = Fri Nov 28 15:09:37 EST 2008
 *   -> failed = false
 *   -> latency = 0
 *   -> name = com.example.MyClass.myMethod
 *   -> sequenceId = m
 *   -> startTime = Fri Nov 28 15:09:37 EST 2008
 *   -> threadId = b92dc2
 * </pre>
 * 
 * </p>
 */
public class SimpleMonitorRenderer implements MonitorRenderer {
  private ToStringStyle toStringStyle = ToStringStyle.SIMPLE_STYLE;

  public ToStringStyle getToStringStyle() {
    return toStringStyle;
  }

  /**
   * Renders a Monitor in a multiple-line String format.
   * @param monitor monitor to render
   * @return a String representation of the monitor.
   */
  public String renderMonitor(Monitor monitor) {
    return renderMonitor(monitor, false);
  }

  /**
   * Renders a Monitor in a multiple-line String format.
   * @param monitor monitor to render
   * @param includeStackTraces true if every Throwable attribute value should render with a stack 
   *     trace
   * @return a String representation of the monitor.
   */
  public String renderMonitor(Monitor monitor, boolean includeStackTraces) {

    if (monitor == null) {
      return "null";
    }

    StringBuffer buf = new StringBuffer(monitor.getClass().getName());

    Map attributeMap = monitor.getAll();

    buf.append(renderMonitor(attributeMap, includeStackTraces));

    return buf.toString();
  }

  public void setToStringStyle(ToStringStyle toStringStyle) {
    this.toStringStyle = toStringStyle;
  }

  private ToStringBuilder createToStringBuilder(Object v) {
    return new ToStringBuilder(v, toStringStyle);
  }

  /**
   * Renders an attribute map in xml format, will not contain the monitor's classname
   * @param attributeMap
   * @param includeStackTraces true if every Throwable attribute value should render with a stack 
   *     trace
   * @return a string representation of the attribute map in multiple-line format
   */
  private String renderMonitor(Map attributeMap, boolean includeStackTraces) {
    if (attributeMap == null) {
      return "null";
    }

    StringBuffer buf = new StringBuffer();

    Map allAttributes = new TreeMap(attributeMap);
    for (Iterator i = allAttributes.entrySet().iterator(); i.hasNext();) {
      Map.Entry e = (Map.Entry) i.next();
      buf.append("\n\t-> ").append(e.getKey()).append(" = ");

      Object v = e.getValue();
      if (shouldHandleStackTraces(includeStackTraces, v)) {
        StringWriter sw = new StringWriter();
        PrintWriter pw = new PrintWriter(sw);
        ((Throwable) v).printStackTrace(pw);
        buf.append(sw.toString());
      } else {
        buf.append(createToStringBuilder(v).append(v));
      }
    }

    return buf.toString();
  }

  private boolean shouldHandleStackTraces(boolean includeStackTraces, Object v) {
    return includeStackTraces && Throwable.class.isAssignableFrom(v.getClass());
  }
}