org.slf4j.helpers.NormalizedParameters Maven / Gradle / Ivy
package org.slf4j.helpers;
import org.slf4j.event.LoggingEvent;
/**
* Holds normalized call parameters.
*
* Includes utility methods such as {@link #normalize(String, Object[], Throwable)} to help the normalization of parameters.
*
* @author ceki
* @since 2.0
*/
public class NormalizedParameters {
final String message;
final Object[] arguments;
final Throwable throwable;
public NormalizedParameters(String message, Object[] arguments, Throwable throwable) {
this.message = message;
this.arguments = arguments;
this.throwable = throwable;
}
public NormalizedParameters(String message, Object[] arguments) {
this(message, arguments, null);
}
public String getMessage() {
return message;
}
public Object[] getArguments() {
return arguments;
}
public Throwable getThrowable() {
return throwable;
}
/**
* Helper method to determine if an {@link Object} array contains a
* {@link Throwable} as last element
*
* @param argArray The arguments off which we want to know if it contains a
* {@link Throwable} as last element
* @return if the last {@link Object} in argArray is a {@link Throwable} this
* method will return it, otherwise it returns null
*/
public static Throwable getThrowableCandidate(final Object[] argArray) {
if (argArray == null || argArray.length == 0) {
return null;
}
final Object lastEntry = argArray[argArray.length - 1];
if (lastEntry instanceof Throwable) {
return (Throwable) lastEntry;
}
return null;
}
/**
* Helper method to get all but the last element of an array
*
* @param argArray The arguments from which we want to remove the last element
*
* @return a copy of the array without the last element
*/
public static Object[] trimmedCopy(final Object[] argArray) {
if (argArray == null || argArray.length == 0) {
throw new IllegalStateException("non-sensical empty or null argument array");
}
final int trimmedLen = argArray.length - 1;
Object[] trimmed = new Object[trimmedLen];
if (trimmedLen > 0) {
System.arraycopy(argArray, 0, trimmed, 0, trimmedLen);
}
return trimmed;
}
/**
* This method serves to normalize logging call invocation parameters.
*
* More specifically, if a throwable argument is not supplied directly, it
* attempts to extract it from the argument array.
*/
public static NormalizedParameters normalize(String msg, Object[] arguments, Throwable t) {
if (t != null) {
return new NormalizedParameters(msg, arguments, t);
}
if (arguments == null || arguments.length == 0) {
return new NormalizedParameters(msg, arguments, t);
}
Throwable throwableCandidate = NormalizedParameters.getThrowableCandidate(arguments);
if (throwableCandidate != null) {
Object[] trimmedArguments = MessageFormatter.trimmedCopy(arguments);
return new NormalizedParameters(msg, trimmedArguments, throwableCandidate);
} else {
return new NormalizedParameters(msg, arguments);
}
}
public static NormalizedParameters normalize(LoggingEvent event) {
return normalize(event.getMessage(), event.getArgumentArray(), event.getThrowable());
}
}