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Prefer SLF4J SPI over Log4J in case of log4j-to-slf4j bridge 

Issue: SPR-17586
This commit is contained in:
Juergen Hoeller 2018-12-12 11:16:36 +01:00
parent 73a96c5152
commit 4b4503085a
1 changed files with 40 additions and 20 deletions
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58
spring-jcl/src/main/java/org/apache/commons/logging/LogAdapter.java
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@ -36,31 +36,41 @@ import org.slf4j.spi.LocationAwareLogger;
*/ */
final class LogAdapter { final class LogAdapter {
private static LogApi logApi = LogApi.JUL; private static final String LOG4J_SPI = "org.apache.logging.log4j.spi.ExtendedLogger";
private static final String LOG4J_SLF4J_PROVIDER = "org.apache.logging.slf4j.SLF4JProvider";
private static final String SLF4J_SPI = "org.slf4j.spi.LocationAwareLogger";
private static final String SLF4J_API = "org.slf4j.Logger";
private static final LogApi logApi;
static { static {
ClassLoader cl = LogAdapter.class.getClassLoader(); if (isPresent(LOG4J_SPI)) {
try { if (isPresent(LOG4J_SLF4J_PROVIDER) && isPresent(SLF4J_SPI)) {
// Try Log4j 2.x API // log4j-to-slf4j bridge -> we'll rather go with the SLF4J SPI;
Class.forName("org.apache.logging.log4j.spi.ExtendedLogger", false, cl); // however, we still prefer Log4j over the plain SLF4J API since
logApi = LogApi.LOG4J; // the latter does not have location awareness support.
}
catch (ClassNotFoundException ex1) {
try {
// Try SLF4J 1.7 SPI
Class.forName("org.slf4j.spi.LocationAwareLogger", false, cl);
logApi = LogApi.SLF4J_LAL; logApi = LogApi.SLF4J_LAL;
} }
catch (ClassNotFoundException ex2) { else {
try { // Use Log4j 2.x directly, including location awareness support
// Try SLF4J 1.7 API logApi = LogApi.LOG4J;
Class.forName("org.slf4j.Logger", false, cl); }
}
else if (isPresent(SLF4J_SPI)) {
// Full SLF4J SPI including location awareness support
logApi = LogApi.SLF4J_LAL;
}
else if (isPresent(SLF4J_API)) {
// Minimal SLF4J API without location awareness support
logApi = LogApi.SLF4J; logApi = LogApi.SLF4J;
} }
catch (ClassNotFoundException ex3) { else {
// Keep java.util.logging as default // java.util.logging as default
} logApi = LogApi.JUL;
}
} }
} }
@ -92,6 +102,16 @@ final class LogAdapter {
} }
} }
private static boolean isPresent(String className) {
try {
Class.forName(className, false, LogAdapter.class.getClassLoader());
return true;
}
catch (ClassNotFoundException ex) {
return false;
}
}
private enum LogApi {LOG4J, SLF4J_LAL, SLF4J, JUL} private enum LogApi {LOG4J, SLF4J_LAL, SLF4J, JUL}