1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16package com.example.android.common.logger;
17
18import android.util.Log;
19
20/**
21 * Helper class which wraps Android's native Log utility in the Logger interface.  This way
22 * normal DDMS output can be one of the many targets receiving and outputting logs simultaneously.
23 */
24public class LogWrapper implements LogNode {
25
26    // For piping:  The next node to receive Log data after this one has done its work.
27    private LogNode mNext;
28
29    /**
30     * Returns the next LogNode in the linked list.
31     */
32    public LogNode getNext() {
33        return mNext;
34    }
35
36    /**
37     * Sets the LogNode data will be sent to..
38     */
39    public void setNext(LogNode node) {
40        mNext = node;
41    }
42
43    /**
44     * Prints data out to the console using Android's native log mechanism.
45     * @param priority Log level of the data being logged.  Verbose, Error, etc.
46     * @param tag Tag for for the log data.  Can be used to organize log statements.
47     * @param msg The actual message to be logged. The actual message to be logged.
48     * @param tr If an exception was thrown, this can be sent along for the logging facilities
49     *           to extract and print useful information.
50     */
51    @Override
52    public void println(int priority, String tag, String msg, Throwable tr) {
53        // There actually are log methods that don't take a msg parameter.  For now,
54        // if that's the case, just convert null to the empty string and move on.
55        String useMsg = msg;
56        if (useMsg == null) {
57            useMsg = "";
58        }
59
60        // If an exeption was provided, convert that exception to a usable string and attach
61        // it to the end of the msg method.
62        if (tr != null) {
63            msg += "\n" + Log.getStackTraceString(tr);
64        }
65
66        // This is functionally identical to Log.x(tag, useMsg);
67        // For instance, if priority were Log.VERBOSE, this would be the same as Log.v(tag, useMsg)
68        Log.println(priority, tag, useMsg);
69
70        // If this isn't the last node in the chain, move things along.
71        if (mNext != null) {
72            mNext.println(priority, tag, msg, tr);
73        }
74    }
75}
76