The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2006 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 | */ |
| 16 | |
| 17 | package android.util; |
| 18 | |
| 19 | import com.android.internal.os.RuntimeInit; |
| 20 | |
| 21 | import java.io.PrintWriter; |
| 22 | import java.io.StringWriter; |
| 23 | |
| 24 | /** |
| 25 | * API for sending log output. |
| 26 | * |
| 27 | * <p>Generally, use the Log.v() Log.d() Log.i() Log.w() and Log.e() |
| 28 | * methods. |
| 29 | * |
| 30 | * <p>The order in terms of verbosity, from least to most is |
| 31 | * ERROR, WARN, INFO, DEBUG, VERBOSE. Verbose should never be compiled |
| 32 | * into an application except during development. Debug logs are compiled |
| 33 | * in but stripped at runtime. Error, warning and info logs are always kept. |
| 34 | * |
| 35 | * <p><b>Tip:</b> A good convention is to declare a <code>TAG</code> constant |
| 36 | * in your class: |
| 37 | * |
| 38 | * <pre>private static final String TAG = "MyActivity";</pre> |
| 39 | * |
| 40 | * and use that in subsequent calls to the log methods. |
| 41 | * </p> |
| 42 | * |
| 43 | * <p><b>Tip:</b> Don't forget that when you make a call like |
| 44 | * <pre>Log.v(TAG, "index=" + i);</pre> |
| 45 | * that when you're building the string to pass into Log.d, the compiler uses a |
| 46 | * StringBuilder and at least three allocations occur: the StringBuilder |
| 47 | * itself, the buffer, and the String object. Realistically, there is also |
| 48 | * another buffer allocation and copy, and even more pressure on the gc. |
| 49 | * That means that if your log message is filtered out, you might be doing |
| 50 | * significant work and incurring significant overhead. |
| 51 | */ |
| 52 | public final class Log { |
| 53 | |
| 54 | /** |
| 55 | * Priority constant for the println method; use Log.v. |
| 56 | */ |
| 57 | public static final int VERBOSE = 2; |
| 58 | |
| 59 | /** |
| 60 | * Priority constant for the println method; use Log.d. |
| 61 | */ |
| 62 | public static final int DEBUG = 3; |
| 63 | |
| 64 | /** |
| 65 | * Priority constant for the println method; use Log.i. |
| 66 | */ |
| 67 | public static final int INFO = 4; |
| 68 | |
| 69 | /** |
| 70 | * Priority constant for the println method; use Log.w. |
| 71 | */ |
| 72 | public static final int WARN = 5; |
| 73 | |
| 74 | /** |
| 75 | * Priority constant for the println method; use Log.e. |
| 76 | */ |
| 77 | public static final int ERROR = 6; |
| 78 | |
| 79 | /** |
| 80 | * Priority constant for the println method. |
| 81 | */ |
| 82 | public static final int ASSERT = 7; |
| 83 | |
Dan Egnor | 60d8762 | 2009-12-16 16:32:58 -0800 | [diff] [blame] | 84 | /** |
| 85 | * Exception class used to capture a stack trace in {@link #wtf()}. |
| 86 | */ |
| 87 | private static class TerribleFailure extends Exception { |
| 88 | TerribleFailure(String msg, Throwable cause) { super(msg, cause); } |
| 89 | } |
| 90 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 91 | private Log() { |
| 92 | } |
| 93 | |
| 94 | /** |
| 95 | * Send a {@link #VERBOSE} log message. |
| 96 | * @param tag Used to identify the source of a log message. It usually identifies |
| 97 | * the class or activity where the log call occurs. |
| 98 | * @param msg The message you would like logged. |
| 99 | */ |
| 100 | public static int v(String tag, String msg) { |
| 101 | return println(VERBOSE, tag, msg); |
| 102 | } |
| 103 | |
| 104 | /** |
| 105 | * Send a {@link #VERBOSE} log message and log the exception. |
| 106 | * @param tag Used to identify the source of a log message. It usually identifies |
| 107 | * the class or activity where the log call occurs. |
| 108 | * @param msg The message you would like logged. |
| 109 | * @param tr An exception to log |
| 110 | */ |
| 111 | public static int v(String tag, String msg, Throwable tr) { |
| 112 | return println(VERBOSE, tag, msg + '\n' + getStackTraceString(tr)); |
| 113 | } |
| 114 | |
| 115 | /** |
| 116 | * Send a {@link #DEBUG} log message. |
| 117 | * @param tag Used to identify the source of a log message. It usually identifies |
| 118 | * the class or activity where the log call occurs. |
| 119 | * @param msg The message you would like logged. |
| 120 | */ |
| 121 | public static int d(String tag, String msg) { |
| 122 | return println(DEBUG, tag, msg); |
| 123 | } |
| 124 | |
| 125 | /** |
| 126 | * Send a {@link #DEBUG} log message and log the exception. |
| 127 | * @param tag Used to identify the source of a log message. It usually identifies |
| 128 | * the class or activity where the log call occurs. |
| 129 | * @param msg The message you would like logged. |
| 130 | * @param tr An exception to log |
| 131 | */ |
| 132 | public static int d(String tag, String msg, Throwable tr) { |
| 133 | return println(DEBUG, tag, msg + '\n' + getStackTraceString(tr)); |
| 134 | } |
| 135 | |
| 136 | /** |
| 137 | * Send an {@link #INFO} log message. |
| 138 | * @param tag Used to identify the source of a log message. It usually identifies |
| 139 | * the class or activity where the log call occurs. |
| 140 | * @param msg The message you would like logged. |
| 141 | */ |
| 142 | public static int i(String tag, String msg) { |
| 143 | return println(INFO, tag, msg); |
| 144 | } |
| 145 | |
| 146 | /** |
| 147 | * Send a {@link #INFO} log message and log the exception. |
| 148 | * @param tag Used to identify the source of a log message. It usually identifies |
| 149 | * the class or activity where the log call occurs. |
| 150 | * @param msg The message you would like logged. |
| 151 | * @param tr An exception to log |
| 152 | */ |
| 153 | public static int i(String tag, String msg, Throwable tr) { |
| 154 | return println(INFO, tag, msg + '\n' + getStackTraceString(tr)); |
| 155 | } |
| 156 | |
| 157 | /** |
| 158 | * Send a {@link #WARN} log message. |
| 159 | * @param tag Used to identify the source of a log message. It usually identifies |
| 160 | * the class or activity where the log call occurs. |
| 161 | * @param msg The message you would like logged. |
| 162 | */ |
| 163 | public static int w(String tag, String msg) { |
| 164 | return println(WARN, tag, msg); |
| 165 | } |
| 166 | |
| 167 | /** |
| 168 | * Send a {@link #WARN} log message and log the exception. |
| 169 | * @param tag Used to identify the source of a log message. It usually identifies |
| 170 | * the class or activity where the log call occurs. |
| 171 | * @param msg The message you would like logged. |
| 172 | * @param tr An exception to log |
| 173 | */ |
| 174 | public static int w(String tag, String msg, Throwable tr) { |
| 175 | return println(WARN, tag, msg + '\n' + getStackTraceString(tr)); |
| 176 | } |
| 177 | |
| 178 | /** |
| 179 | * Checks to see whether or not a log for the specified tag is loggable at the specified level. |
Dan Egnor | 60d8762 | 2009-12-16 16:32:58 -0800 | [diff] [blame] | 180 | * |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 181 | * The default level of any tag is set to INFO. This means that any level above and including |
| 182 | * INFO will be logged. Before you make any calls to a logging method you should check to see |
| 183 | * if your tag should be logged. You can change the default level by setting a system property: |
| 184 | * 'setprop log.tag.<YOUR_LOG_TAG> <LEVEL>' |
Dan Egnor | 60d8762 | 2009-12-16 16:32:58 -0800 | [diff] [blame] | 185 | * Where level is either VERBOSE, DEBUG, INFO, WARN, ERROR, ASSERT, or SUPPRESS. SUPPRESS will |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 186 | * turn off all logging for your tag. You can also create a local.prop file that with the |
| 187 | * following in it: |
| 188 | * 'log.tag.<YOUR_LOG_TAG>=<LEVEL>' |
| 189 | * and place that in /data/local.prop. |
Dan Egnor | 60d8762 | 2009-12-16 16:32:58 -0800 | [diff] [blame] | 190 | * |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 191 | * @param tag The tag to check. |
| 192 | * @param level The level to check. |
| 193 | * @return Whether or not that this is allowed to be logged. |
| 194 | * @throws IllegalArgumentException is thrown if the tag.length() > 23. |
| 195 | */ |
| 196 | public static native boolean isLoggable(String tag, int level); |
Dan Egnor | 60d8762 | 2009-12-16 16:32:58 -0800 | [diff] [blame] | 197 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 198 | /* |
| 199 | * Send a {@link #WARN} log message and log the exception. |
| 200 | * @param tag Used to identify the source of a log message. It usually identifies |
| 201 | * the class or activity where the log call occurs. |
| 202 | * @param tr An exception to log |
| 203 | */ |
| 204 | public static int w(String tag, Throwable tr) { |
| 205 | return println(WARN, tag, getStackTraceString(tr)); |
| 206 | } |
| 207 | |
| 208 | /** |
| 209 | * Send an {@link #ERROR} log message. |
| 210 | * @param tag Used to identify the source of a log message. It usually identifies |
| 211 | * the class or activity where the log call occurs. |
| 212 | * @param msg The message you would like logged. |
| 213 | */ |
| 214 | public static int e(String tag, String msg) { |
| 215 | return println(ERROR, tag, msg); |
| 216 | } |
| 217 | |
| 218 | /** |
| 219 | * Send a {@link #ERROR} log message and log the exception. |
| 220 | * @param tag Used to identify the source of a log message. It usually identifies |
| 221 | * the class or activity where the log call occurs. |
| 222 | * @param msg The message you would like logged. |
| 223 | * @param tr An exception to log |
| 224 | */ |
| 225 | public static int e(String tag, String msg, Throwable tr) { |
Dan Egnor | b7f0367 | 2009-12-09 16:22:32 -0800 | [diff] [blame] | 226 | return println(ERROR, tag, msg + '\n' + getStackTraceString(tr)); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 227 | } |
| 228 | |
| 229 | /** |
Dan Egnor | 60d8762 | 2009-12-16 16:32:58 -0800 | [diff] [blame] | 230 | * What a Terrible Failure: Report a condition that should never happen. |
| 231 | * The error will always be logged at level ASSERT with the call stack. |
| 232 | * Depending on system configuration, a report may be added to the |
| 233 | * {@link android.os.DropBoxManager} and/or the process may be terminated |
| 234 | * immediately with an error dialog. |
| 235 | * @param tag Used to identify the source of a log message. |
| 236 | * @param msg The message you would like logged. |
Dan Egnor | 60d8762 | 2009-12-16 16:32:58 -0800 | [diff] [blame] | 237 | */ |
| 238 | public static int wtf(String tag, String msg) { |
| 239 | return wtf(tag, msg, null); |
| 240 | } |
| 241 | |
| 242 | /** |
| 243 | * What a Terrible Failure: Report an exception that should never happen. |
| 244 | * Similar to {@link #wtf(String, String)}, with an exception to log. |
| 245 | * @param tag Used to identify the source of a log message. |
| 246 | * @param tr An exception to log. |
Dan Egnor | 60d8762 | 2009-12-16 16:32:58 -0800 | [diff] [blame] | 247 | */ |
| 248 | public static int wtf(String tag, Throwable tr) { |
| 249 | return wtf(tag, tr.getMessage(), tr); |
| 250 | } |
| 251 | |
| 252 | /** |
| 253 | * What a Terrible Failure: Report an exception that should never happen. |
| 254 | * Similar to {@link #wtf(String, Throwable)}, with a message as well. |
| 255 | * @param tag Used to identify the source of a log message. |
| 256 | * @param msg The message you would like logged. |
| 257 | * @param tr An exception to log. May be null. |
Dan Egnor | 60d8762 | 2009-12-16 16:32:58 -0800 | [diff] [blame] | 258 | */ |
| 259 | public static int wtf(String tag, String msg, Throwable tr) { |
| 260 | tr = new TerribleFailure(msg, tr); |
| 261 | int bytes = println(ASSERT, tag, getStackTraceString(tr)); |
| 262 | RuntimeInit.wtf(tag, tr); |
| 263 | return bytes; |
| 264 | } |
| 265 | |
| 266 | /** |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 267 | * Handy function to get a loggable stack trace from a Throwable |
| 268 | * @param tr An exception to log |
| 269 | */ |
| 270 | public static String getStackTraceString(Throwable tr) { |
| 271 | if (tr == null) { |
| 272 | return ""; |
| 273 | } |
| 274 | StringWriter sw = new StringWriter(); |
| 275 | PrintWriter pw = new PrintWriter(sw); |
| 276 | tr.printStackTrace(pw); |
| 277 | return sw.toString(); |
| 278 | } |
| 279 | |
| 280 | /** |
| 281 | * Low-level logging call. |
| 282 | * @param priority The priority/type of this log message |
| 283 | * @param tag Used to identify the source of a log message. It usually identifies |
| 284 | * the class or activity where the log call occurs. |
| 285 | * @param msg The message you would like logged. |
| 286 | * @return The number of bytes written. |
| 287 | */ |
| 288 | public static native int println(int priority, String tag, String msg); |
| 289 | } |