Siphalor/tweed5-commons-logging
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[LOGGING-186] Replace custom code with ServiceLoader call (#171)

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* Replace custom code with `ServiceLoader` call

* Files should end with an empty line

* Files should end with an empty line

* Comment empty block

* Comment empty block

---------

Co-authored-by: Gary Gregory <garydgregory@users.noreply.github.com>
This commit is contained in:
Piotr P. Karwasz
2023-10-18 22:47:48 +02:00
committed by GitHub
parent 2ec80207a5
commit ca2cdfee81
8 changed files with 187 additions and 32 deletions
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54
src/main/java/org/apache/commons/logging/LogFactory.java
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@@ -30,7 +30,10 @@ import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Properties;
import java.util.ServiceConfigurationError;
import java.util.ServiceLoader;
/**
* Factory for creating {@link Log} instances, with discovery and
@@ -189,6 +192,12 @@ public abstract class LogFactory {
*/
private static final WeakReference<ClassLoader> thisClassLoaderRef;
/**
* Maximum number of {@link ServiceLoader} errors to ignore, while
* looking for an implementation.
*/
private static final int MAX_BROKEN_SERVICES = 3;
// ----------------------------------------------------------- Constructors
/**
@@ -507,42 +516,25 @@ public abstract class LogFactory {
if (factory == null) {
if (isDiagnosticsEnabled()) {
logDiagnostic("[LOOKUP] Looking for a resource file of name [" + SERVICE_ID +
"] to define the LogFactory subclass to use...");
logDiagnostic("[LOOKUP] Using ServiceLoader to define the LogFactory subclass to use...");
}
try {
final InputStream is = getResourceAsStream(contextClassLoader, SERVICE_ID);
final ServiceLoader<LogFactory> serviceLoader = ServiceLoader.load(LogFactory.class);
final Iterator<LogFactory> iterator = serviceLoader.iterator();
if ( is != null ) {
// This code is needed by EBCDIC and other strange systems.
// It's a fix for bugs reported in xerces
BufferedReader rd;
int i = MAX_BROKEN_SERVICES;
while (factory == null && i-- > 0) {
try {
rd = new BufferedReader(new InputStreamReader(is, "UTF-8"));
} catch (final java.io.UnsupportedEncodingException e) {
rd = new BufferedReader(new InputStreamReader(is));
}
String factoryClassName;
try {
factoryClassName = rd.readLine();
} finally {
rd.close();
}
if (factoryClassName != null && ! factoryClassName.isEmpty()) {
if (isDiagnosticsEnabled()) {
logDiagnostic("[LOOKUP] Creating an instance of LogFactory class " +
factoryClassName +
" as specified by file '" + SERVICE_ID +
"' which was present in the path of the context classloader.");
if (iterator.hasNext()) {
factory = iterator.next();
}
} catch (final ServiceConfigurationError | LinkageError ex) {
if (isDiagnosticsEnabled()) {
logDiagnostic("[LOOKUP] An exception occurred while trying to find an" +
" instance of LogFactory" +
": [" + trim(ex.getMessage()) +
"]. Trying alternative implementations...");
}
factory = newFactory(factoryClassName, baseClassLoader, contextClassLoader );
}
} else {
// is == null
if (isDiagnosticsEnabled()) {
logDiagnostic("[LOOKUP] No resource file with name '" + SERVICE_ID + "' found.");
}
}
} catch (final Exception ex) {