Create new logging class in the common library.

The goal is to later migrate all existing code to this
new logger and get rid of all our duplicates.

Also did a misc fix in AndroidLocation.

Change-Id: Ia33a782b57c91b4e3d5fd2c0660e040be11b9cbb

4 files changed, 309 insertions, 1 deletions

diff --git a/common/src/com/android/prefs/AndroidLocation.java b/common/src/com/android/prefs/AndroidLocation.java
index c36048a..66c0248 100644
--- a/common/src/com/android/prefs/AndroidLocation.java
+++ b/common/src/com/android/prefs/AndroidLocation.java
@@ -16,6 +16,8 @@
 
 package com.android.prefs;
 
+import com.android.annotations.NonNull;
+
 import java.io.File;
 
 /**
@@ -45,7 +47,7 @@ public final class AndroidLocation {
      * @return an OS specific path, terminated by a separator.
      * @throws AndroidLocationException
      */
-    public final static String getFolder() throws AndroidLocationException {
+    @NonNull public final static String getFolder() throws AndroidLocationException {
         if (sPrefsLocation == null) {
             String home = findValidPath("ANDROID_SDK_HOME", "user.home", "HOME");
 
diff --git a/common/src/com/android/utils/ILogger.java b/common/src/com/android/utils/ILogger.java
new file mode 100644
index 0000000..df3a636
--- /dev/null
+++ b/common/src/com/android/utils/ILogger.java
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed 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.
+ */
+
+package com.android.utils;
+
+import com.android.annotations.NonNull;
+
+import java.util.Formatter;
+
+/**
+ * Interface used to display warnings/errors while parsing the SDK content.
+ * <p/>
+ * There are a few default implementations available:
+ * <ul>
+ * <li> {@link NullLogger} is an implementation that does <em>nothing</em> with the log.
+ *  Useful for limited cases where you need to call a class that requires a non-null logging
+ *  yet the calling code does not have any mean of reporting logs itself. It can be
+ *  acceptable for use as a temporary implementation but most of the time that means the caller
+ *  code needs to be reworked to take a logger object from its own caller.
+ * </li>
+ * <li> {@link StdLogger} is an implementation that dumps the log to {@link System#out} or
+ *  {@link System#err}. This is useful for unit tests or code that does not have any GUI.
+ *  GUI based apps based should not use it and should provide a better way to report to the user.
+ * </li>
+ * </ul>
+ */
+public interface ILogger {
+
+    /**
+     * Prints an error message.
+     *
+     * @param t is an optional {@link Throwable} or {@link Exception}. If non-null, its
+     *          message will be printed out.
+     * @param msgFormat is an optional error format. If non-null, it will be printed
+     *          using a {@link Formatter} with the provided arguments.
+     * @param args provides the arguments for errorFormat.
+     */
+    void error(Throwable t, String msgFormat, Object... args);
+
+    /**
+     * Prints a warning message.
+     *
+     * @param msgFormat is a string format to be used with a {@link Formatter}. Cannot be null.
+     * @param args provides the arguments for warningFormat.
+     */
+    void warning(@NonNull String msgFormat, Object... args);
+
+    /**
+     * Prints an information message.
+     *
+     * @param msgFormat is a string format to be used with a {@link Formatter}. Cannot be null.
+     * @param args provides the arguments for msgFormat.
+     */
+    void info(@NonNull String msgFormat, Object... args);
+
+    /**
+     * Prints a verbose message.
+     *
+     * @param msgFormat is a string format to be used with a {@link Formatter}. Cannot be null.
+     * @param args provides the arguments for msgFormat.
+     */
+    void verbose(String msgFormat, Object... args);
+
+}
diff --git a/common/src/com/android/utils/NullLogger.java b/common/src/com/android/utils/NullLogger.java
new file mode 100644
index 0000000..77f1ad5
--- /dev/null
+++ b/common/src/com/android/utils/NullLogger.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed 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.
+ */
+
+package com.android.utils;
+
+/**
+ * Dummy implementation of an {@link ILogger}.
+ * <p/>
+ * Use {@link #getLogger()} to get a default instance of this {@link NullLogger}.
+ */
+public class NullLogger implements ILogger {
+
+    private static final ILogger sThis = new NullLogger();
+
+    public static ILogger getLogger() {
+        return sThis;
+    }
+
+    @Override
+    public void error(Throwable t, String errorFormat, Object... args) {
+        // ignore
+    }
+
+    @Override
+    public void warning(String warningFormat, Object... args) {
+        // ignore
+    }
+
+    @Override
+    public void info(String msgFormat, Object... args) {
+        // ignore
+    }
+
+    @Override
+    public void verbose(String msgFormat, Object... args) {
+        // ignore
+    }
+
+}
diff --git a/common/src/com/android/utils/StdLogger.java b/common/src/com/android/utils/StdLogger.java
new file mode 100644
index 0000000..c0de06f
--- /dev/null
+++ b/common/src/com/android/utils/StdLogger.java
@@ -0,0 +1,177 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed 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.
+ */
+
+package com.android.utils;
+
+import com.android.SdkConstants;
+import com.android.annotations.NonNull;
+
+import java.io.PrintStream;
+import java.util.Formatter;
+
+
+/**
+ * An implementation of {@link ILogger} that prints to {@link System#out} and {@link System#err}.
+ * <p/>
+ *
+ */
+public class StdLogger implements ILogger {
+
+    private final Level mLevel;
+
+    public enum Level {
+        VERBOSE(0),
+        INFO(1),
+        WARNING(2),
+        ERROR(3);
+
+        private final int mLevel;
+
+        Level(int level) {
+            mLevel = level;
+        }
+    }
+
+    /**
+     * Creates the {@link StdLogger} with a given log {@link Level}.
+     * @param level the log Level.
+     */
+    public StdLogger(@NonNull Level level) {
+        if (level == null) {
+            throw new IllegalArgumentException("level cannot be null");
+        }
+
+        mLevel = level;
+    }
+
+    /**
+     * Returns the logger's log {@link Level}.
+     * @return the log level.
+     */
+    public Level getLevel() {
+        return mLevel;
+    }
+
+    /**
+     * Prints an error message.
+     * <p/>
+     * The message will be tagged with "Error" on the output so the caller does not
+     * need to put such a prefix in the format string.
+     * <p/>
+     * The output is done on {@link System#err}.
+     * <p/>
+     * This is always displayed, independent of the logging {@link Level}.
+     *
+     * @param t is an optional {@link Throwable} or {@link Exception}. If non-null, it's
+     *          message will be printed out.
+     * @param errorFormat is an optional error format. If non-null, it will be printed
+     *          using a {@link Formatter} with the provided arguments.
+     * @param args provides the arguments for errorFormat.
+     */
+    @Override
+    public void error(Throwable t, String errorFormat, Object... args) {
+        if (errorFormat != null) {
+            String msg = String.format("Error: " + errorFormat, args);
+
+            printMessage(msg, System.err);
+        }
+        if (t != null) {
+            System.err.println(String.format("Error: %1$s", t.getMessage()));
+        }
+    }
+
+    /**
+     * Prints a warning message.
+     * <p/>
+     * The message will be tagged with "Warning" on the output so the caller does not
+     * need to put such a prefix in the format string.
+     * <p/>
+     * The output is done on {@link System#out}.
+     * <p/>
+     * This is displayed only if the logging {@link Level} is {@link Level#WARNING} or higher.
+     *
+     * @param msgFormat is a string format to be used with a {@link Formatter}. Cannot be null.
+     * @param args provides the arguments for warningFormat.
+     */
+    @Override
+    public void warning(@NonNull String warningFormat, Object... args) {
+        if (mLevel.mLevel > Level.WARNING.mLevel) {
+            return;
+        }
+
+        String msg = String.format("Warning: " + warningFormat, args);
+
+        printMessage(msg, System.out);
+    }
+
+    /**
+     * Prints an info message.
+     * <p/>
+     * The output is done on {@link System#out}.
+     * <p/>
+     * This is displayed only if the logging {@link Level} is {@link Level#INFO} or higher.
+     *
+     * @param msgFormat is a string format to be used with a {@link Formatter}. Cannot be null.
+     * @param args provides the arguments for msgFormat.
+     */
+    @Override
+    public void info(@NonNull String msgFormat, Object... args) {
+        if (mLevel.mLevel > Level.INFO.mLevel) {
+            return;
+        }
+
+        String msg = String.format(msgFormat, args);
+
+        printMessage(msg, System.out);
+    }
+
+    /**
+     * Prints a verbose message.
+     * <p/>
+     * The output is done on {@link System#out}.
+     * <p/>
+     * This is displayed only if the logging {@link Level} is {@link Level#VERBOSE} or higher.
+     *
+     * @param msgFormat is a string format to be used with a {@link Formatter}. Cannot be null.
+     * @param args provides the arguments for msgFormat.
+     */
+    @Override
+    public void verbose(@NonNull String msgFormat, Object... args) {
+        if (mLevel.mLevel > Level.VERBOSE.mLevel) {
+            return;
+        }
+
+        String msg = String.format(msgFormat, args);
+
+        printMessage(msg, System.out);
+    }
+
+    private void printMessage(String msg, PrintStream stream) {
+        if (SdkConstants.CURRENT_PLATFORM == SdkConstants.PLATFORM_WINDOWS &&
+                !msg.endsWith("\r\n") &&
+                msg.endsWith("\n")) {
+            // remove last \n so that println can use \r\n as needed.
+            msg = msg.substring(0, msg.length() - 1);
+        }
+
+        stream.print(msg);
+
+        if (!msg.endsWith("\n")) {
+            stream.println();
+        }
+    }
+
+}