package org.slf4j.agent;import static org.slf4j.helpers.MessageFormatter.format;import java.io.ByteArrayInputStream;import java.io.IOException;import java.lang.instrument.Instrumentation;import java.util.Date;import java.util.Properties;import org.slf4j.instrumentation.LogTransformer;/** * Entry point for slf4j-ext when used as a Java agent. *  */public class AgentPremain {  private static final String START_MSG = "Start at {}";  private static final String STOP_MSG = "Stop at {}, execution time = {} ms";  /**   * JavaAgent premain entry point as specified in the MANIFEST.MF file. See   * {@link http://java.sun.com/javase/6/docs/api/java/lang/instrument/package-summary.html}   *  for details.   *    * @param agentArgument   *          string provided after "=" up to first space   * @param instrumentation   *          instrumentation environment provided by the JVM   */  public static void premain(String agentArgument,      Instrumentation instrumentation) {    LogTransformer.Builder builder = new LogTransformer.Builder();    builder = builder.addEntryExit(true);    if (agentArgument != null) {      Properties args = parseArguments(agentArgument, ",");      if (args.containsKey(AgentOptions.VERBOSE)) {        builder = builder.verbose(true);      }      if (args.containsKey(AgentOptions.TIME)) {        printStartStopTimes();      }      if (args.containsKey(AgentOptions.IGNORE)) {        String ignore = args.getProperty(AgentOptions.IGNORE);        builder = builder.ignore(ignore.split(":"));      }      if (args.containsKey(AgentOptions.LEVEL)) {        builder = builder.level(args.getProperty(AgentOptions.LEVEL));      }    }    instrumentation.addTransformer(builder.build());  }  /**   * Consider the argument string to be a property file (by converting the   * splitter character to line feeds), and then reading it like any other   * property file.   *    *    * @param agentArgument   *          string given by instrumentation framework   * @param separator   *          String to convert to line feeds   * @return argument converted to properties   */  private static Properties parseArguments(String agentArgument,      String separator) {    Properties p = new Properties();    try {      String argumentAsLines = agentArgument.replaceAll(separator, "\n");      p.load(new ByteArrayInputStream(argumentAsLines.getBytes()));    } catch (IOException e) {      String s = "Could not load arguments as properties";      throw new RuntimeException(s, e);    }    return p;  }  /**   * Print the start message to System.err with the time NOW, and register a   * shutdown hook which will print the stop message to System.err with the time   * then and the number of milliseconds passed since.   *    */  private static void printStartStopTimes() {    final long start = System.currentTimeMillis();    System.err.println(format(START_MSG, new Date()));    Thread hook = new Thread() {      @Override      public void run() {        long timePassed = System.currentTimeMillis() - start;        String message = format(STOP_MSG, new Date(), timePassed);        System.err.println(message);      }    };    Runtime.getRuntime().addShutdownHook(hook);  }}