package org.apache.juli.logging; /** * 日志接口API。为了能够被LogFactory实例,实现这个Log接口的类必须要包含 * 含有单个字符串作为参数的构造函数,这个字符串参数用来作为日志的名字。 * Log含有6个日志级别: * trace * debug * info * warn * error * fatal * * The mapping of these log levels to the concepts used by the underlying * logging system is implementation dependent. * The implementation should ensure, though, that this ordering behaves * as expected.</p> * * <p>Performance is often a logging concern. * By examining the appropriate property, * a component can avoid expensive operations (producing information * to be logged).</p> * * <p> For example, * <code><pre> * if (log.isDebugEnabled()) { * ... do something expensive ... * log.debug(theResult); * } * </pre></code> * </p> * * <p>Configuration of the underlying logging system will generally be done * external to the Logging APIs, through whatever mechanism is supported by * that system.</p> * * @author <a href="mailto:sanders@apache.org">Scott Sanders</a> * @author Rod Waldhoff */ public interface Log { // ----------------------------------------------------- Logging Properties /** * <p> Is debug logging currently enabled? </p> * * <p> Call this method to prevent having to perform expensive operations * (for example, <code>String</code> concatenation) * when the log level is more than debug. </p> */ public boolean isDebugEnabled(); /** * <p> Is error logging currently enabled? </p> * * <p> Call this method to prevent having to perform expensive operations * (for example, <code>String</code> concatenation) * when the log level is more than error. </p> */ public boolean isErrorEnabled(); /** * <p> Is fatal logging currently enabled? </p> * * <p> Call this method to prevent having to perform expensive operations * (for example, <code>String</code> concatenation) * when the log level is more than fatal. </p> */ public boolean isFatalEnabled(); /** * <p> Is info logging currently enabled? </p> * * <p> Call this method to prevent having to perform expensive operations * (for example, <code>String</code> concatenation) * when the log level is more than info. </p> */ public boolean isInfoEnabled(); /** * <p> Is trace logging currently enabled? </p> * * <p> Call this method to prevent having to perform expensive operations * (for example, <code>String</code> concatenation) * when the log level is more than trace. </p> */ public boolean isTraceEnabled(); /** * <p> Is warn logging currently enabled? </p> * * <p> Call this method to prevent having to perform expensive operations * (for example, <code>String</code> concatenation) * when the log level is more than warn. </p> */ public boolean isWarnEnabled(); // -------------------------------------------------------- Logging Methods /** * <p> Log a message with trace log level. </p> * * @param message log this message */ public void trace(Object message); /** * <p> Log an error with trace log level. </p> * * @param message log this message * @param t log this cause */ public void trace(Object message, Throwable t); /** * <p> Log a message with debug log level. </p> * * @param message log this message */ public void debug(Object message); /** * <p> Log an error with debug log level. </p> * * @param message log this message * @param t log this cause */ public void debug(Object message, Throwable t); /** * <p> Log a message with info log level. </p> * * @param message log this message */ public void info(Object message); /** * <p> Log an error with info log level. </p> * * @param message log this message * @param t log this cause */ public void info(Object message, Throwable t); /** * <p> Log a message with warn log level. </p> * * @param message log this message */ public void warn(Object message); /** * <p> Log an error with warn log level. </p> * * @param message log this message * @param t log this cause */ public void warn(Object message, Throwable t); /** * <p> Log a message with error log level. </p> * * @param message log this message */ public void error(Object message); /** * <p> Log an error with error log level. </p> * * @param message log this message * @param t log this cause */ public void error(Object message, Throwable t); /** * <p> Log a message with fatal log level. </p> * * @param message log this message */ public void fatal(Object message); /** * <p> Log an error with fatal log level. </p> * * @param message log this message * @param t log this cause */ public void fatal(Object message, Throwable t); }