extracted Slf4jConfiguration interface and corresponding implementation

to clearly separate code depending on slf4j binding

still need to add automatic selection of implementation

maven-embedder/src/main/java/org/apache/maven/cli/MavenCli.java

@@ -39,8 +39,10 @@ import org.apache.maven.InternalErrorException;
 import org.apache.maven.Maven;
 import org.apache.maven.cli.event.DefaultEventSpyContext;
 import org.apache.maven.cli.event.ExecutionEventLogger;
+import org.apache.maven.cli.logging.Slf4jConfiguration;
 import org.apache.maven.cli.logging.Slf4jLoggerManager;
 import org.apache.maven.cli.logging.Slf4jStdoutLogger;
+import org.apache.maven.cli.logging.impl.Slf4jSimpleConfiguration;
 import org.apache.maven.cli.transfer.ConsoleMavenTransferListener;
 import org.apache.maven.cli.transfer.QuietMavenTransferListener;
 import org.apache.maven.cli.transfer.Slf4jMavenTransferListener;
@@ -131,6 +133,8 @@ public class MavenCli
 
     private DefaultSecDispatcher dispatcher;
 
+    private Slf4jConfiguration slf4jConfiguration = new Slf4jSimpleConfiguration();
+
     public MavenCli()
     {
         this( null );
@@ -306,24 +310,24 @@ public class MavenCli
         if ( cliRequest.debug )
         {
             cliRequest.request.setLoggingLevel( MavenExecutionRequest.LOGGING_LEVEL_DEBUG );
-            System.setProperty( "org.slf4j.simpleLogger.defaultLogLevel", "debug" );            
+            slf4jConfiguration.setRootLoggerLevel( MavenExecutionRequest.LOGGING_LEVEL_DEBUG );
         }
         else if ( cliRequest.quiet )
         {
             cliRequest.request.setLoggingLevel( MavenExecutionRequest.LOGGING_LEVEL_ERROR );
-            System.setProperty( "org.slf4j.simpleLogger.defaultLogLevel", "error" );            
+            slf4jConfiguration.setRootLoggerLevel( MavenExecutionRequest.LOGGING_LEVEL_ERROR );
         }
         else
         {
             cliRequest.request.setLoggingLevel( MavenExecutionRequest.LOGGING_LEVEL_INFO );
-            System.setProperty( "org.slf4j.simpleLogger.defaultLogLevel", "info" );
+            slf4jConfiguration.setRootLoggerLevel( MavenExecutionRequest.LOGGING_LEVEL_INFO );
         }
 
         if ( cliRequest.commandLine.hasOption( CLIManager.LOG_FILE ) )
         {
             File logFile = new File( cliRequest.commandLine.getOptionValue( CLIManager.LOG_FILE ) );
             logFile = resolveFile( logFile, cliRequest.workingDirectory );
-            System.setProperty( "org.slf4j.simpleLogger.logFile", logFile.getAbsolutePath() );
+            slf4jConfiguration.setLoggerFile( logFile );
             try
             {
                 PrintStream ps = new PrintStream( new FileOutputStream( logFile ) );

maven-embedder/src/main/java/org/apache/maven/cli/logging/AbstractSlf4jConfiguration.java

@@ -0,0 +1,46 @@
+package org.apache.maven.cli.logging;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import java.io.File;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Abstract implementation.
+ * 
+ * @author Hervé Boutemy
+ */
+public class AbstractSlf4jConfiguration
+    implements Slf4jConfiguration
+{
+    private final Logger logger = LoggerFactory.getLogger( AbstractSlf4jConfiguration.class );
+
+    public void setRootLoggerLevel( int level )
+    {
+        logger.warn( "setRootLoggerLevel: operation not supported" );
+    }
+
+    public void setLoggerFile( File output )
+    {
+        logger.warn( "setLoggerFile: operation not supported" );
+    }
+}

maven-embedder/src/main/java/org/apache/maven/cli/logging/Slf4jConfiguration.java

@@ -0,0 +1,35 @@
+package org.apache.maven.cli.logging;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import java.io.File;
+
+/**
+ * Interface for configuration operations on loggers, which are not available in slf4j, then require per-slf4f-binding
+ * implementation.
+ * 
+ * @author Hervé Boutemy
+ */
+public interface Slf4jConfiguration
+{
+    void setRootLoggerLevel( int level );
+
+    void setLoggerFile( File output );
+}

maven-embedder/src/main/java/org/apache/maven/cli/logging/impl/Slf4jSimpleConfiguration.java

@@ -0,0 +1,62 @@
+package org.apache.maven.cli.logging.impl;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import java.io.File;
+
+import org.apache.maven.cli.logging.AbstractSlf4jConfiguration;
+import org.apache.maven.cli.logging.Slf4jConfiguration;
+import org.apache.maven.execution.MavenExecutionRequest;
+import org.codehaus.plexus.component.annotations.Component;
+
+/**
+ * Configuration for slf4j-simple.
+ * 
+ * @author Hervé Boutemy
+ */
+@Component( role = Slf4jConfiguration.class )
+public class Slf4jSimpleConfiguration
+    extends AbstractSlf4jConfiguration
+{
+    public void setRootLoggerLevel( int level )
+    {
+        String value = "info";
+        switch ( level )
+        {
+            case MavenExecutionRequest.LOGGING_LEVEL_DEBUG:
+                value = "debug";
+                break;
+            
+            case MavenExecutionRequest.LOGGING_LEVEL_INFO:
+                value = "info";
+                break;
+
+            case MavenExecutionRequest.LOGGING_LEVEL_ERROR:
+                value = "error";
+                break;
+        }
+        System.setProperty( "org.slf4j.simpleLogger.defaultLogLevel", value );
+    }
+
+    public void setLoggerFile( File output )
+    {
+        System.setProperty( "org.slf4j.simpleLogger.logFile", output.getAbsolutePath() );
+    }
+}