Android example source code file (AndroidHandler.java)

This example Android source code file (AndroidHandler.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, androidhandler, dalvikloghandler, error, formatter, info, io, level, log, logging, override, printwriter, runtimeexception, string, stringwriter, the_formatter, throwable, util, utilities, warning

The AndroidHandler.java Android example source code

/*
 * Copyright (C) 2008 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.internal.logging;

import android.util.Log;
import dalvik.system.DalvikLogging;
import dalvik.system.DalvikLogHandler;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.logging.Formatter;
import java.util.logging.Handler;
import java.util.logging.Level;
import java.util.logging.LogRecord;
import java.util.logging.Logger;

/**
 * Implements a {@link java.util.logging.Logger} handler that writes to the Android log. The
 * implementation is rather straightforward. The name of the logger serves as
 * the log tag. Only the log levels need to be converted appropriately. For
 * this purpose, the following mapping is being used:
 * 
 * <table>
 *   <tr>
 *     <th>logger level
 *     <th>Android level
 *   </tr>
 *   <tr>
 *     <td>
 *       SEVERE
 *     </td>
 *     <td>
 *       ERROR
 *     </td>
 *   </tr>
 *   <tr>
 *     <td>
 *       WARNING
 *     </td>
 *     <td>
 *       WARN
 *     </td>
 *   </tr>
 *   <tr>
 *     <td>
 *       INFO
 *     </td>
 *     <td>
 *       INFO
 *     </td>
 *   </tr>
 *   <tr>
 *     <td>
 *       CONFIG
 *     </td>
 *     <td>
 *       DEBUG
 *     </td>
 *   </tr>
 *   <tr>
 *     <td>
 *       FINE, FINER, FINEST
 *     </td>
 *     <td>
 *       VERBOSE
 *     </td>
 *   </tr>
 * </table>
 */
public class AndroidHandler extends Handler implements DalvikLogHandler {
    /**
     * Holds the formatter for all Android log handlers.
     */
    private static final Formatter THE_FORMATTER = new Formatter() {
        @Override
        public String format(LogRecord r) {
            Throwable thrown = r.getThrown();
            if (thrown != null) {
                StringWriter sw = new StringWriter();
                PrintWriter pw = new PrintWriter(sw);
                sw.write(r.getMessage());
                sw.write("\n");
                thrown.printStackTrace(pw);
                pw.flush();
                return sw.toString();
            } else {
                return r.getMessage();
            }
        }
    };

    /**
     * Constructs a new instance of the Android log handler.
     */
    public AndroidHandler() {
        setFormatter(THE_FORMATTER);
    }

    @Override
    public void close() {
        // No need to close, but must implement abstract method.
    }

    @Override
    public void flush() {
        // No need to flush, but must implement abstract method.
    }

    @Override
    public void publish(LogRecord record) {
        int level = getAndroidLevel(record.getLevel());
        String tag = DalvikLogging.loggerNameToTag(record.getLoggerName());
        if (!Log.isLoggable(tag, level)) {
            return;
        }

        try {
            String message = getFormatter().format(record);
            Log.println(level, tag, message);
        } catch (RuntimeException e) {
            Log.e("AndroidHandler", "Error logging message.", e);
        }
    }

    public void publish(Logger source, String tag, Level level, String message) {
        // TODO: avoid ducking into native 2x; we aren't saving any formatter calls
        int priority = getAndroidLevel(level);
        if (!Log.isLoggable(tag, priority)) {
            return;
        }

        try {
            Log.println(priority, tag, message);
        } catch (RuntimeException e) {
            Log.e("AndroidHandler", "Error logging message.", e);
        }
    }

    /**
     * Converts a {@link java.util.logging.Logger} logging level into an Android one.
     *
     * @param level The {@link java.util.logging.Logger} logging level.
     *
     * @return The resulting Android logging level.
     */
    static int getAndroidLevel(Level level) {
        int value = level.intValue();
        if (value >= 1000) { // SEVERE
            return Log.ERROR;
        } else if (value >= 900) { // WARNING
            return Log.WARN;
        } else if (value >= 800) { // INFO
            return Log.INFO;
        } else {
            return Log.DEBUG;
        }
    }
}