add GlobalExceptionHandler

core/pom.xml

@@ -11,4 +11,11 @@
   <packaging>jar</packaging>
   <name>${project.artifactId}</name>
   <description>Basic interfaces and classes for reuse.</description>
+  <dependencies>
+    <dependency>
+      <groupId>org.slf4j</groupId>
+      <artifactId>slf4j-api</artifactId>
+      <optional>true</optional>
+    </dependency>
+  </dependencies>
 </project>

core/src/main/java/io/github/mmm/base/exception/GlobalExceptionHandler.java

@@ -0,0 +1,25 @@
+/* Copyright (c) The m-m-m Team, Licensed under the Apache License, Version 2.0
+ * http://www.apache.org/licenses/LICENSE-2.0 */
+package io.github.mmm.base.exception;
+
+/**
+ * Interface used as fallback to {@link #handleError(Object, Throwable) handle an error} that can not be handled in a
+ * specific way by generic components. It allows to write portable code that can delegate error handling to this
+ * interface allowing to exchange its implementation and therefore the handling strategy.
+ */
+public interface GlobalExceptionHandler {
+
+  /**
+   * This method handles an error that occurred in a generic component that can not handle it in a specific way. <br>
+   * In a typical server application you may like to log the errors while in a client application you might want to show
+   * a popup that displays the error.
+   *
+   * @param context is an Object with information about the context when the error occurred. Its
+   *        {@link Object#toString() string representation} should be human readable and give additional hints to track
+   *        down the error. E.g. the source or parameters of an operation where the error occurred. This parameter may
+   *        also be {@code null} if no context information is available.
+   * @param error is the {@link Throwable error} that has been catched and shall be handled.
+   */
+  void handleError(Object context, Throwable error);
+
+}

core/src/main/java/io/github/mmm/base/exception/GlobalExceptionHandlerAccess.java

@@ -0,0 +1,27 @@
+package io.github.mmm.base.exception;
+
+import java.util.ServiceLoader;
+
+import io.github.mmm.base.config.ServiceHelper;
+
+/**
+ * Class giving {@link #get() global access} to the {@link GlobalExceptionHandler} implementation.
+ */
+public final class GlobalExceptionHandlerAccess {
+
+  private static final GlobalExceptionHandler HANDLER = ServiceHelper
+      .singleton(ServiceLoader.load(GlobalExceptionHandler.class), false);
+
+  private GlobalExceptionHandlerAccess() {
+
+  }
+
+  /**
+   * @return the {@link GlobalExceptionHandler} instance.
+   */
+  public static GlobalExceptionHandler get() {
+
+    return HANDLER;
+  }
+
+}

core/src/main/java/io/github/mmm/base/exception/GlobalExceptionHandlerSlf4j.java

@@ -0,0 +1,19 @@
+package io.github.mmm.base.exception;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Implementation of {@link GlobalExceptionHandler} using SLF4J {@link Logger}.
+ */
+public class GlobalExceptionHandlerSlf4j implements GlobalExceptionHandler {
+
+  private static final Logger LOG = LoggerFactory.getLogger(GlobalExceptionHandlerSlf4j.class);
+
+  @Override
+  public void handleError(Object context, Throwable error) {
+
+    LOG.warn("Unhandeled error in {}", context, error);
+  }
+
+}

core/src/main/java/io/github/mmm/base/exception/GlobalExceptionHandlerSysout.java

@@ -0,0 +1,14 @@
+package io.github.mmm.base.exception;
+
+/**
+ * Implementation of {@link GlobalExceptionHandler} that simply performs a {@link Throwable#printStackTrace()}.
+ */
+public class GlobalExceptionHandlerSysout implements GlobalExceptionHandler {
+
+  @Override
+  public void handleError(Object context, Throwable error) {
+
+    error.printStackTrace();
+  }
+
+}

core/src/main/java/module-info.java

@@ -7,15 +7,24 @@
  * Provides fundamental APIs and helper classes.
  *
  * @provides io.github.mmm.base.temporal.TemporalConverter
+ * @provides io.github.mmm.base.exception.GlobalExceptionHandler
+ * @uses io.github.mmm.base.exception.GlobalExceptionHandler
  * @uses io.github.mmm.base.temporal.TemporalConverter
  */
 module io.github.mmm.base {
 
+  requires static org.slf4j;
+
   uses io.github.mmm.base.temporal.TemporalConverter;
 
   provides io.github.mmm.base.temporal.TemporalConverter with //
       io.github.mmm.base.temporal.impl.TemporalConverterImpl;
 
+  uses io.github.mmm.base.exception.GlobalExceptionHandler;
+
+  provides io.github.mmm.base.exception.GlobalExceptionHandler
+      with io.github.mmm.base.exception.GlobalExceptionHandlerSysout;
+
   exports io.github.mmm.base.collection;
 
   exports io.github.mmm.base.compare;