ibatis 2.3x logging 加载机制， 输出sqlmap jdbc日志信息

ibatis  支持三种日志框架输出jdbc logging，加载顺序如下：

public class LogFactory {  private static Constructor logConstructor;  static {    tryImplementation("org.apache.commons.logging.LogFactory", "com.ibatis.common.logging.jakarta.JakartaCommonsLoggingImpl");    tryImplementation("org.apache.log4j.Logger", "com.ibatis.common.logging.log4j.Log4jImpl");    tryImplementation("java.util.logging.Logger", "com.ibatis.common.logging.jdk14.Jdk14LoggingImpl");    tryImplementation("java.lang.Object", "com.ibatis.common.logging.nologging.NoLoggingImpl");//No logging 什么都不输出，等于没有  }  private static void tryImplementation(String testClassName, String implClassName) {    if (logConstructor == null) {      try {        Resources.classForName(testClassName);        Class implClass = Resources.classForName(implClassName);        logConstructor = implClass.getConstructor(new Class[]{Class.class});      } catch (Throwable t) {      }    }  }...}