Diff of /jakarta/commons/proper/logging/trunk/src/java/org/apache/commons/logging/impl/LogFactoryImpl.java
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--- jakarta/commons/proper/logging/trunk/src/java/org/apache/commons/logging/impl/LogFactoryImpl.java 2005/06/02 07:31:22 179545
+++ jakarta/commons/proper/logging/trunk/src/java/org/apache/commons/logging/impl/LogFactoryImpl.java 2005/06/02 07:39:39 179546
@@ -468,20 +468,9 @@ public class LogFactoryImpl extends LogF
* it will be.
*/
protected boolean isJdk13LumberjackAvailable() {
-
- logDiagnostic("Checking for Jdk13Lumberjack.");
- try {
- createLogFromClass("org.apache.commons.logging.impl.Jdk13LumberjackLogger",
- getClass().getName(),
- false);
- // No exception means success
- logDiagnostic("Found Jdk13Lumberjack.");
- return true;
- } catch (Throwable t) {
- logDiagnostic("Did not find Jdk13Lumberjack.");
- return false;
- }
-
+ return isLogLibraryAvailable(
+ "Jdk13Lumberjack",
+ "org.apache.commons.logging.impl.Jdk13LumberjackLogger");
}
@@ -495,19 +484,9 @@ public class LogFactoryImpl extends LogF
* it will be.
*/
protected boolean isJdk14Available() {
-
- logDiagnostic("Checking for Jdk14.");
- try {
- createLogFromClass("org.apache.commons.logging.impl.Jdk14Logger",
- getClass().getName(),
- false);
- // No exception means success
- logDiagnostic("Found Jdk14.");
- return true;
- } catch (Throwable t) {
- logDiagnostic("Did not find Jdk14.");
- return false;
- }
+ return isLogLibraryAvailable(
+ "Jdk14",
+ "org.apache.commons.logging.impl.Jdk14Logger");
}
@@ -518,19 +497,9 @@ public class LogFactoryImpl extends LogF
* it will be.
*/
protected boolean isLog4JAvailable() {
-
- logDiagnostic("Checking for Log4J");
- try {
- createLogFromClass("org.apache.commons.logging.impl.Log4JLogger",
- getClass().getName(),
- false);
- // No exception means success
- logDiagnostic("Found Log4J.");
- return true;
- } catch (Throwable t) {
- logDiagnostic("Did not find Log4J");
- return false;
- }
+ return isLogLibraryAvailable(
+ "Log4J",
+ "org.apache.commons.logging.impl.Log4JLogger");
}
@@ -589,6 +558,33 @@ public class LogFactoryImpl extends LogF
// ------------------------------------------------------ Private Methods
/**
+ * Utility method to check whether a particular logging library is
+ * present and available for use. Note that this does <i>not</i>
+ * affect the future behaviour of this class.
+ */
+ private boolean isLogLibraryAvailable(String name, String classname) {
+ logDiagnostic("Checking for " + name + ".");
+ try {
+ Log log = createLogFromClass(
+ classname,
+ this.getClass().getName(), // dummy category
+ false);
+
+ if (log == null) {
+ logDiagnostic("Did not find " + name + ".");
+ return false;
+ } else {
+ logDiagnostic("Found " + name + ".");
+ return true;
+ }
+ } catch(LogConfigurationException e) {
+ logDiagnostic("Logging system " + name + " is available but not useable.");
+ return false;
+ }
+ }
+
+
+ /**
* Attempts to create a Log instance for the given category name.
* Follows the discovery process described in the class javadoc.
*
@@ -599,6 +595,7 @@ public class LogFactoryImpl extends LogF
* instantiated
*/
private Log discoverLogImplementation(String logCategory)
+ throws LogConfigurationException
{
logDiagnostic("Attempting to discover a Log implementation.");
@@ -608,101 +605,42 @@ public class LogFactoryImpl extends LogF
String specifiedLogClassName = findUserSpecifiedLogClassName();
if (specifiedLogClassName != null) {
- try {
- // note: createLogFromClass never returns null..
- result = createLogFromClass(specifiedLogClassName,
- logCategory,
- true);
- return result;
- } catch (LogConfigurationException ex) {
- // this type of exception means we've already output
- // diagnostics about this issue, etc.; just pass it on
- throw ex;
- } catch (Throwable t) {
- // log problem, and throw a LogConfigurationException
- // wrapping the Throwable
- handleFlawedDiscovery(specifiedLogClassName, null, t);
-
- // handleFlawedDiscovery should have thrown an LCE, but
- // in case it didn't we'll throw one. Inability to
- // instantiate a user specified class is a fatal error
- throw new LogConfigurationException("Unable to instantiate "
- + specifiedLogClassName,
- t);
+ // note: createLogFromClass never returns null..
+ result = createLogFromClass(specifiedLogClassName,
+ logCategory,
+ true);
+ if (result == null) {
+ throw new LogConfigurationException(
+ "User-specified log class " + specifiedLogClassName
+ + " cannot be found or is not useable.");
}
-
- // this if-statement never exits!
+
+ return result;
}
// No user specified log; try to discover what's on the classpath
// Try Log4j
- try {
- result = createLogFromClass("org.apache.commons.logging.impl.Log4JLogger",
- logCategory,
- true);
- } catch (LogConfigurationException lce) {
-
- // LCE means we had a flawed discovery and already
- // output diagnostics; just pass it on
- throw (LogConfigurationException) lce;
-
- } catch (Throwable t) {
- // Other throwables just mean couldn't load the adapter
- // or log4j; continue with discovery
- }
+ result = createLogFromClass("org.apache.commons.logging.impl.Log4JLogger",
+ logCategory,
+ true);
if (result == null) {
- // Try JDK 1.4 Logging
- try {
- result = createLogFromClass("org.apache.commons.logging.impl.Jdk14Logger",
- logCategory,
- true);
- } catch (LogConfigurationException lce) {
-
- // LCE means we had a flawed discovery and already
- // output diagnostics; just pass it on
- throw (LogConfigurationException) lce;
-
- } catch (Throwable t) {
- // Other throwables just mean couldn't load the adapter
- // or j.u.l; continue with discovery
- }
+ result = createLogFromClass("org.apache.commons.logging.impl.Jdk14Logger",
+ logCategory,
+ true);
}
if (result == null) {
- // Try Lumberjack
- try {
- result = createLogFromClass("org.apache.commons.logging.impl.Jdk13LumberjackLogger",
- logCategory,
- true);
- } catch (LogConfigurationException lce) {
-
- // LCE means we had a flawed discovery and already
- // output diagnostics; just pass it on
- throw (LogConfigurationException) lce;
-
- } catch (Throwable t) {
- // Other throwables just mean couldn't load the adapter
- // or j.u.l; continue with discovery
- }
+ result = createLogFromClass("org.apache.commons.logging.impl.Jdk13LumberjackLogger",
+ logCategory,
+ true);
}
if (result == null) {
- // Try SimpleLog
- try {
- result = createLogFromClass("org.apache.commons.logging.impl.SimpleLog",
- logCategory,
- true);
- } catch (LogConfigurationException lce) {
-
- // LCE means we had a flawed discovery and already
- // output diagnostics; just pass it up
- throw (LogConfigurationException) lce;
-
- } catch (Throwable t) {
- // Other throwables just mean couldn't load the adapter
- }
+ result = createLogFromClass("org.apache.commons.logging.impl.SimpleLog",
+ logCategory,
+ true);
}
if (result == null) {
@@ -768,57 +706,61 @@ public class LogFactoryImpl extends LogF
* be affected by this method call, <code>false</code>
* otherwise.
*
- * @return an instance of the given class. Will not return
- * <code>null</code>.
+ * @return an instance of the given class, or null if the logging
+ * library associated with the specified adapter is not available.
*
- * @throws LinkageError if any linkage provoked by this method fails
- * @throws ExceptionInInitializerError if any initialization provoked
- * by this method fails
- * @throws ClassNotFoundException if the class cannot be located
- * @throws NoClassDefFoundError if <code>logImplClass</code> could be
- * loaded but the logging implementation it
- * relies on could not be located
- * @throws LogConfigurationException if the class was loaded but no suitable
- * logger could be created and this object
- * is configured to fail in such a
- * situation
+ * @throws LogConfigurationException if there was a serious error with
+ * configuration and the handleFlawedDiscovery method decided this
+ * problem was fatal.
*/
private Log createLogFromClass(String logAdapterClass,
String logCategory,
boolean affectState)
- throws Throwable {
+ throws LogConfigurationException {
logDiagnostic("Attempting to instantiate " + logAdapterClass);
- Class logClass = loadClass(logAdapterClass);
+ Class logClass = null;
Object[] params = { logCategory };
- Log result = null;
+ Log logAdapter = null;
Constructor constructor = null;
try {
+ logClass = loadClass(logAdapterClass);
constructor = logClass.getConstructor(logConstructorSignature);
- result = (Log) constructor.newInstance(params);
+ logAdapter = (Log) constructor.newInstance(params);
} catch (NoClassDefFoundError e) {
- // We were able to load the adapter but its underlying
- // logger library could not be found. This is normal and not
- // a "flawed discovery", so just throw the error on
- logDiagnostic("Unable to load logging library used by "
- + logAdapterClass);
- throw e;
- } catch (Throwable t) {
- // ExceptionInInitializerError
- // NoSuchMethodException
- // InvocationTargetException
- // ClassCastException
- // All mean the adapter and underlying logger library were found
- // but there was a problem creating an instance.
- // This is a "flawed discovery"
-
+ // We were able to load the adapter but it had references to
+ // other classes that could not be found. This simply means that
+ // the underlying logger library could not be found.
+ String msg = "" + e.getMessage();
+ logDiagnostic(
+ "The logging library used by "
+ + logAdapterClass
+ + " is not available: "
+ + msg.trim());
+ return null;
+ } catch (ExceptionInInitializerError e) {
+ // A static initializer block or the initializer code associated
+ // with a static variable on the log adapter class has thrown
+ // an exception.
+ //
+ // We treat this as meaning the adapter's underlying logging
+ // library could not be found.
+ String msg = "" + e.getMessage();
+ logDiagnostic(
+ "The logging library used by "
+ + logAdapterClass
+ + " is not available: "
+ + msg.trim());
+ return null;
+ } catch(Throwable t) {
+ // handleFlawedDiscovery will determine whether this is a fatal
+ // problem or not. If it is fatal, then a LogConfigurationException
+ // will be thrown.
handleFlawedDiscovery(logAdapterClass, logClass, t);
- // handleFlawedDiscovery should have thrown an LCE, but
- // in case it didn't we'll throw one
- throw new LogConfigurationException(t);
- }
+ return null;
+ }
if (affectState) {
// We've succeeded, so set instance fields
@@ -838,8 +780,7 @@ public class LogFactoryImpl extends LogF
}
}
- return result;
-
+ return logAdapter;
}
