Log4j components cannot make log4j logging calls. However, it is + sometimes useful for the user to learn about what log4j is + doing. You can enable log4j internal logging by defining the + log4j.configDebug variable. + +
All log4j internal debug calls go to System.out
+ where as internal error messages are sent to
+ System.err. All internal messages are prepended with
+ the string "log4j: ".
+
+ @since 0.8.2
+ @author Ceki Gülcü
+*/
+public class LogLog {
+
+ /**
+ Defining this value makes log4j print log4j-internal debug
+ statements to System.out.
+
+
The value of this string is log4j.debug. + +
Note that the search for all option names is case sensitive. */
+ public static final String DEBUG_KEY="log4j.debug";
+
+
+ /**
+ Defining this value makes log4j components print log4j-internal
+ debug statements to System.out.
+
+
The value of this string is log4j.configDebug. + +
Note that the search for all option names is case sensitive.
+
+ @deprecated Use {@link #DEBUG_KEY} instead.
+ */
+ public static final String CONFIG_DEBUG_KEY="log4j.configDebug";
+
+ protected static boolean debugEnabled = false;
+
+ /**
+ In quietMode not even errors generate any output.
+ */
+ private static boolean quietMode = false;
+
+ private static final String PREFIX = "log4j: ";
+ private static final String ERR_PREFIX = "log4j:ERROR ";
+ private static final String WARN_PREFIX = "log4j:WARN ";
+
+ static {
+ String key = OptionConverter.getSystemProperty(DEBUG_KEY, null);
+
+ if(key == null) {
+ key = OptionConverter.getSystemProperty(CONFIG_DEBUG_KEY, null);
+ }
+
+ if(key != null) {
+ debugEnabled = OptionConverter.toBoolean(key, true);
+ }
+ }
+
+ /**
+ Allows to enable/disable log4j internal logging.
+ */
+ static
+ public
+ void setInternalDebugging(boolean enabled) {
+ debugEnabled = enabled;
+ }
+
+ /**
+ This method is used to output log4j internal debug
+ statements. Output goes to System.out.
+ */
+ public
+ static
+ void debug(String msg) {
+ if(debugEnabled && !quietMode) {
+ System.out.println(PREFIX+msg);
+ }
+ }
+
+ /**
+ This method is used to output log4j internal debug
+ statements. Output goes to System.out.
+ */
+ public
+ static
+ void debug(String msg, Throwable t) {
+ if(debugEnabled && !quietMode) {
+ System.out.println(PREFIX+msg);
+ if(t != null) {
+ t.printStackTrace(System.out);
+ }
+ }
+ }
+
+
+ /**
+ This method is used to output log4j internal error
+ statements. There is no way to disable error statements.
+ Output goes to System.err.
+ */
+ public
+ static
+ void error(String msg) {
+ if(quietMode) {
+ return;
+ }
+ System.err.println(ERR_PREFIX+msg);
+ }
+
+ /**
+ This method is used to output log4j internal error
+ statements. There is no way to disable error statements.
+ Output goes to System.err.
+ */
+ public
+ static
+ void error(String msg, Throwable t) {
+ if(quietMode) {
+ return;
+ }
+
+ System.err.println(ERR_PREFIX+msg);
+ if(t != null) {
+ t.printStackTrace();
+ }
+ }
+
+ /**
+ In quite mode no LogLog generates strictly no output, not even
+ for errors.
+
+ @param quietMode A true for not
+ */
+ public
+ static
+ void setQuietMode(boolean quietMode) {
+ LogLog.quietMode = quietMode;
+ }
+
+ /**
+ This method is used to output log4j internal warning
+ statements. There is no way to disable warning statements.
+ Output goes to System.err. */
+ public
+ static
+ void warn(String msg) {
+ if(quietMode) {
+ return;
+ }
+
+ System.err.println(WARN_PREFIX+msg);
+ }
+
+ /**
+ This method is used to output log4j internal warnings. There is
+ no way to disable warning statements. Output goes to
+ System.err. */
+ public
+ static
+ void warn(String msg, Throwable t) {
+ if(quietMode) {
+ return;
+ }
+
+ System.err.println(WARN_PREFIX+msg);
+ if(t != null) {
+ t.printStackTrace();
+ }
+ }
+}