public abstract class AndroidLogFactory extends Object
Factory for creating Log instances, with discovery and configuration features similar to that employed by standard Java APIs such as JAXP.
IMPLEMENTATION NOTE - This implementation is heavily based on the SAXParserFactory and DocumentBuilderFactory implementations (corresponding to the JAXP pluggability APIs) found in Apache Xerces.
| Modifier and Type | Field and Description |
|---|---|
static String |
DIAGNOSTICS_DEST_PROPERTY
The name (
org.apache.commons.logging.diagnostics.dest) of the property used to enable internal commons-logging diagnostic output,
in order to get information on what logging implementations are being discovered, what classloaders they are loaded through, etc. |
protected static Map<ClassLoader,AndroidLogFactory> |
factories
The previously constructed
AndroidLogFactory instances, keyed by the ClassLoader with which it was created. |
static String |
FACTORY_DEFAULT
The fully qualified class name of the fallback
AndroidLogFactory implementation class to use, if no other can be found. |
static String |
FACTORY_PROPERTIES
The name (
android-commons-logging.properties) of the properties file to search for. |
static String |
FACTORY_PROPERTY
The name (
org.apache.commons.logging.LogFactory) of the property used to identify the AndroidLogFactory implementation class name. |
static String |
PRIORITY_KEY
The name (
priority) of the key in the config file used to specify the priority of that particular config file. |
| Modifier | Constructor and Description |
|---|---|
protected |
AndroidLogFactory()
Protected constructor that is not available for public use.
|
| Modifier and Type | Method and Description |
|---|---|
protected static Object |
createFactory(String factoryClass,
ClassLoader classLoader) |
abstract Object |
getAttribute(String name)
Return the configuration attribute with the specified name (if any), or
null if there is no such attribute. |
abstract String[] |
getAttributeNames()
Return an array containing the names of all currently defined configuration attributes.
|
protected static ClassLoader |
getClassLoader(Class<?> clazz)
Safely get access to the classloader for the specified class.
|
static AndroidLogFactory |
getFactory()
Construct (if necessary) and return a
AndroidLogFactory instance, using the following ordered lookup procedure to determine the
name of the implementation class to be loaded. |
abstract Log |
getInstance(Class<?> clazz)
Convenience method to derive a name from the specified class and call
getInstance(String) with it. |
abstract Log |
getInstance(String name)
Construct (if necessary) and return a
Log instance, using the factory's current set of configuration attributes. |
static Log |
getLog(Class<?> clazz)
Convenience method to return a named logger, without the application having to care about factories.
|
static Log |
getLog(String name)
Convenience method to return a named logger, without the application having to care about factories.
|
protected static boolean |
isDiagnosticsEnabled() |
protected static void |
logRawDiagnostic(String msg) |
protected static AndroidLogFactory |
newFactory(String factoryClass,
ClassLoader classLoader)
Return a new instance of the specified
AndroidLogFactory implementation class, loaded by the specified class loader. |
static String |
objectId(Object o)
Returns a string that uniquely identifies the specified object, including its class.
|
abstract void |
release()
Release any internal references to previously created
Log instances returned by this factory. |
static void |
release(ClassLoader classLoader)
Release any internal references to previously created
AndroidLogFactory instances that have been associated with the specified class
loader (if any), after calling the instance method release() on each of them. |
static void |
releaseAll()
Release any internal references to previously created
AndroidLogFactory instances, after calling the instance method
release() on each of them. |
abstract void |
removeAttribute(String name)
Remove any configuration attribute associated with the specified name.
|
abstract void |
setAttribute(String name,
Object value)
Set the configuration attribute with the specified name.
|
public static final String PRIORITY_KEY
priority) of the key in the config file used to specify the priority of that particular config file. The associated
value is a floating-point number; higher values take priority over lower values.public static final String FACTORY_PROPERTY
org.apache.commons.logging.LogFactory) of the property used to identify the AndroidLogFactory implementation class name.
This can be used as a system property, or as an entry in a configuration properties file.public static final String FACTORY_DEFAULT
AndroidLogFactory implementation class to use, if no other can be found.public static final String FACTORY_PROPERTIES
android-commons-logging.properties) of the properties file to search for.public static final String DIAGNOSTICS_DEST_PROPERTY
org.apache.commons.logging.diagnostics.dest) of the property used to enable internal commons-logging diagnostic output,
in order to get information on what logging implementations are being discovered, what classloaders they are loaded through, etc.
If a system property of this name is set then the value is assumed to be the name of a file. The special strings STDOUT or STDERR (case-sensitive) indicate output to System.out and System.err respectively.
Diagnostic logging should be used only to debug problematic configurations and should not be set in normal production use.
protected static Map<ClassLoader,AndroidLogFactory> factories
AndroidLogFactory instances, keyed by the ClassLoader with which it was created.protected AndroidLogFactory()
public abstract Object getAttribute(String name)
null if there is no such attribute.name - Name of the attribute to returnpublic abstract String[] getAttributeNames()
public abstract Log getInstance(Class<?> clazz) throws LogConfigurationException
getInstance(String) with it.clazz - Class for which a suitable Log name will be derivedLogConfigurationException - if a suitable Log instance cannot be returnedpublic abstract Log getInstance(String name) throws LogConfigurationException
Construct (if necessary) and return a Log instance, using the factory's current set of configuration attributes.
NOTE - Depending upon the implementation of the AndroidLogFactory you are using, the Log instance
you are returned may or may not be local to the current application, and may or may not be returned again on a subsequent call with the same
name argument.
name - Logical name of the Log instance to be returned (the meaning of this name is only known to the underlying logging
implementation that is being wrapped)LogConfigurationException - if a suitable Log instance cannot be returnedpublic abstract void release()
Log instances returned by this factory. This is useful in environments like
servlet containers, which implement application reloading by throwing away a ClassLoader. Dangling references to objects in that class loader
would prevent garbage collection.public abstract void removeAttribute(String name)
name - Name of the attribute to removepublic abstract void setAttribute(String name, Object value)
null value is equivalent to calling
removeAttribute(name).name - Name of the attribute to setvalue - Value of the attribute to set, or null to remove any setting for this attributepublic static AndroidLogFactory getFactory() throws LogConfigurationException
Construct (if necessary) and return a AndroidLogFactory instance, using the following ordered lookup procedure to determine the
name of the implementation class to be loaded.
org.apache.commons.logging.AndroidLogFactory system property.android-commons-logging.properties file, if found in the class path of this class. The configuration
file is in standard java.util.Properties format and contains the fully qualified name of the implementation class with the key
being the system property defined above.org.apache.commons.logging.impl.AndroidLogFactoryImpl).
NOTE - If the properties file method of identifying the AndroidLogFactory implementation class is utilized, all of the
properties defined in this file will be set as configuration attributes on the corresponding AndroidLogFactory instance.
NOTE - In a multithreaded environment it is possible that two different instances will be returned for the same classloader environment.
LogConfigurationException - if the implementation class is not available or cannot be instantiated.public static Log getLog(Class<?> clazz) throws LogConfigurationException
clazz - Class from which a log name will be derivedLogConfigurationException - if a suitable Log instance cannot be returnedpublic static Log getLog(String name) throws LogConfigurationException
name - Logical name of the Log instance to be returned (the meaning of this name is only known to the underlying logging
implementation that is being wrapped)LogConfigurationException - if a suitable Log instance cannot be returnedpublic static void release(ClassLoader classLoader)
AndroidLogFactory instances that have been associated with the specified class
loader (if any), after calling the instance method release() on each of them.classLoader - ClassLoader for which to release the AndroidLogFactorypublic static void releaseAll()
AndroidLogFactory instances, after calling the instance method
release() on each of them. This is useful in environments like servlet containers, which implement application reloading by
throwing away a ClassLoader. Dangling references to objects in that class loader would prevent garbage collection.protected static ClassLoader getClassLoader(Class<?> clazz)
Theoretically, calling getClassLoader can throw a security exception, and so should be done under an AccessController in order to provide maximum flexibility. However in practice people don't appear to use security policies that forbid getClassLoader calls. So for the moment all code is written to call this method rather than Class.getClassLoader, so that we could put AccessController stuff in this method without any disruption later if we need to.
Even when using an AccessController, however, this method can still throw SecurityException. Commons-logging basically relies on the ability to access classloaders, ie a policy that forbids all classloader access will also prevent commons-logging from working: currently this method will throw an exception preventing the entire app from starting up. Maybe it would be good to detect this situation and just disable all commons-logging? Not high priority though - as stated above, security policies that prevent classloader access aren't common.
Note that returning an object fetched via an AccessController would technically be a security flaw anyway; untrusted code that has access to a trusted JCL library could use it to fetch the classloader for a class even when forbidden to do so directly.
protected static AndroidLogFactory newFactory(String factoryClass, ClassLoader classLoader) throws LogConfigurationException
AndroidLogFactory implementation class, loaded by the specified class loader.factoryClass - Fully qualified name of the AndroidLogFactory implementation classclassLoader - ClassLoader from which to load this classcontextClassLoader - is the context that this new factory will manage logging for.LogConfigurationException - if a suitable instance cannot be createdprotected static Object createFactory(String factoryClass, ClassLoader classLoader)
protected static boolean isDiagnosticsEnabled()
protected static final void logRawDiagnostic(String msg)
public static String objectId(Object o)
The returned string is of form "classname@hashcode", ie is the same as the return value of the Object.toString() method, but works even when the specified object's class has overidden the toString method.
o - may be null.Copyright © 2014. All rights reserved.