1page.title=ProGuard 2parent.title=Tools 3parent.link=index.html 4@jd:body 5 6 <div id="qv-wrapper"> 7 <div id="qv"> 8 <h2>In this document</h2> 9 10 <ol> 11 <li><a href="#enabling">Enabling ProGuard</a></li> 12 13 <li><a href="#configuring">Configuring ProGuard</a></li> 14 15 <li> 16 <a href="#decoding">Decoding Obfuscated Stack Traces</a> 17 18 <ol> 19 <li><a href="#considerations">Debugging considerations for published 20 applications</a></li> 21 </ol> 22 </li> 23 </ol> 24 25 <h2>See also</h2> 26 27 <ol> 28 <li> 29 <a href="http://stuff.mit.edu/afs/sipb/project/android/sdk/android-sdk-linux/tools/proguard/docs/index.html#manual/introduction.html">ProGuard 30 Manual »</a> 31 </li> 32 <li> 33 <a href="http://stuff.mit.edu/afs/sipb/project/android/sdk/android-sdk-linux/tools/proguard/docs/index.html#manual/retrace/introduction.html">ProGuard 34 ReTrace Manual »</a> 35 </li> 36 </ol> 37 </div> 38 </div> 39 40 <p>The ProGuard tool shrinks, optimizes, and obfuscates your code by removing unused code and 41 renaming classes, fields, and methods with semantically obscure names. The result is a smaller 42 sized <code>.apk</code> file that is more difficult to reverse engineer. Because ProGuard makes your 43 application harder to reverse engineer, it is important that you use it 44 when your application utilizes features that are sensitive to security like when you are 45 <a href="{@docRoot}google/play/licensing/index.html">Licensing Your Applications</a>.</p> 46 47 <p>ProGuard is integrated into the Android build system, so you do not have to invoke it 48 manually. ProGuard runs only when you build your application in release mode, so you do not 49 have to deal with obfuscated code when you build your application in debug mode. 50 Having ProGuard run is completely optional, but highly recommended.</p> 51 52 <p>This document describes how to enable and configure ProGuard as well as use the 53 <code>retrace</code> tool to decode obfuscated stack traces.</p> 54 55 <h2 id="enabling">Enabling ProGuard</h2> 56 57 <p>When you create an Android project, a <code>proguard.cfg</code> file is automatically 58 generated in the root directory of the project. This file defines how ProGuard optimizes and 59 obfuscates your code, so it is very important that you understand how to customize it for your 60 needs. The default configuration file only covers general cases, so you most likely have to edit 61 it for your own needs. See the following section about <a href="#configuring">Configuring ProGuard</a> for information on 62 customizing the ProGuard configuration file.</p> 63 64 <p>To enable ProGuard so that it runs as part of an Ant or Eclipse build, set the 65 <code>proguard.config</code> property in the <code><project_root>/project.properties</code> 66 file. The path can be an absolute path or a path relative to the project's root.</p> 67 68<p class="note"><strong>Note:</strong> When using Android Studio, you must add Proguard 69to your <code>gradle.build</code> file's build types. For more information, see the 70<a href="http://tools.android.com/tech-docs/new-build-system/user-guide#TOC-Running-ProGuard" 71>Gradle Plugin User Guide</a>. 72 73<p>If you left the <code>proguard.cfg</code> file in its default location (the project's root directory), 74you can specify its location like this:</p> 75<pre class="no-pretty-print"> 76proguard.config=proguard.cfg 77</pre> 78<p> 79You can also move the the file to anywhere you want, and specify the absolute path to it: 80</p> 81<pre class="no-pretty-print"> 82proguard.config=/path/to/proguard.cfg 83</pre> 84 85 86 <p>When you build your application in release mode, either by running <code>ant release</code> or 87 by using the <em>Export Wizard</em> in Eclipse, the build system automatically checks to see if 88 the <code>proguard.config</code> property is set. If it is, ProGuard automatically processes 89 the application's bytecode before packaging everything into an <code>.apk</code> file. Building in debug mode 90 does not invoke ProGuard, because it makes debugging more cumbersome.</p> 91 92 <p>ProGuard outputs the following files after it runs:</p> 93 94 <dl> 95 <dt><code>dump.txt</code></dt> 96 <dd>Describes the internal structure of all the class files in the <code>.apk</code> file</dd> 97 98 <dt><code>mapping.txt</code></dt> 99 <dd>Lists the mapping between the original and obfuscated class, method, and field names. 100 This file is important when you receive a bug report from a release build, because it 101 translates the obfuscated stack trace back to the original class, method, and member names. 102 See <a href="#decoding">Decoding Obfuscated Stack Traces</a> for more information.</dd> 103 104 <dt><code>seeds.txt</code></dt> 105 <dd>Lists the classes and members that are not obfuscated</dd> 106 107 <dt><code>usage.txt</code></dt> 108 <dd>Lists the code that was stripped from the <code>.apk</code></dd> 109 </ul> 110 111 <p>These files are located in the following directories:</p> 112 113 <ul> 114 <li><code><project_root>/bin/proguard</code> if you are using Ant.</li> 115 116 <li><code><project_root>/proguard</code> if you are using Eclipse.</li> 117 </ul> 118 119 120 <p class="caution"><strong>Caution:</strong> Every time you run a build in release mode, these files are 121 overwritten with the latest files generated by ProGuard. Save a copy of them each time you release your 122 application in order to de-obfuscate bug reports from your release builds. 123 For more information on why saving these files is important, see 124 <a href="#considerations">Debugging considerations for published applications</a>. 125 </p> 126 127 <h2 id="configuring">Configuring ProGuard</h2> 128 129 <p>For some situations, the default configurations in the <code>proguard.cfg</code> file will 130 suffice. However, many situations are hard for ProGuard to analyze correctly and it might remove code 131 that it thinks is not used, but your application actually needs. Some examples include:</p> 132 133 <ul> 134 <li>a class that is referenced only in the <code>AndroidManifest.xml</code> file</li> 135 136 <li>a method called from JNI</li> 137 138 <li>dynamically referenced fields and methods</li> 139 </ul> 140 141 <p>The default <code>proguard.cfg</code> file tries to cover general cases, but you might 142 encounter exceptions such as <code>ClassNotFoundException</code>, which happens when ProGuard 143 strips away an entire class that your application calls.</p> 144 145 <p>You can fix errors when ProGuard strips away your code by adding a <code>-keep</code> line in 146 the <code>proguard.cfg</code> file. For example:</p> 147 <pre> 148-keep public class <MyClass> 149</pre> 150 151 <p>There are many options and considerations when using the <code>-keep</code> option, so it is 152 highly recommended that you read the 153 <a href="http://stuff.mit.edu/afs/sipb/project/android/sdk/android-sdk-linux/tools/proguard/docs/index.html#manual/introduction.html">ProGuard 154 Manual</a> for more information about customizing your configuration file. The 155 <em>Overview of Keep options</em> and <em>Examples</em> sections are particularly helpful. 156 The <a href= 157 "http://stuff.mit.edu/afs/sipb/project/android/sdk/android-sdk-linux/tools/proguard/docs/index.html#manual/troubleshooting.html">Troubleshooting 158 </a> section of the ProGuard Manual outlines other common problems you might encounter 159 when your code gets stripped away.</p> 160 161 <h2 id="decoding">Decoding Obfuscated Stack Traces</h2> 162 163 <p>When your obfuscated code outputs a stack trace, the method names are obfuscated, which makes 164 debugging hard, if not impossible. Fortunately, whenever ProGuard runs, it outputs a 165 <code><project_root>/bin/proguard/mapping.txt</code> file, which shows you the original 166 class, method, and field names mapped to their obfuscated names.</p> 167 168 <p>The <code>retrace.bat</code> script on Windows or the <code>retrace.sh</code> script on Linux 169 or Mac OS X can convert an obfuscated stack trace to a readable one. It is located in the 170 <code><sdk_root>/tools/proguard/</code> directory. The syntax for executing the 171 <code>retrace</code> tool is:</p> 172 <pre>retrace.bat|retrace.sh [-verbose] mapping.txt [<stacktrace_file>]</pre> 173 <p>For example:</p> 174 175 <pre>retrace.bat -verbose mapping.txt obfuscated_trace.txt</pre> 176 177 <p>If you do not specify a value for <em><stacktrace_file></em>, the <code>retrace</code> tool reads 178 from standard input.</p> 179 180 <h3 id="considerations">Debugging considerations for published applications</h3> 181 182 <p>Save the <code>mapping.txt</code> file for every release that you publish to your users. 183 By retaining a copy of the <code>mapping.txt</code> file for each release build, 184 you ensure that you can debug a problem if a user encounters a bug and submits an obfuscated stack trace. 185 A project's <code>mapping.txt</code> file is overwritten every time you do a release build, so you must be 186 careful about saving the versions that you need.</p> 187 188 <p>For example, say you publish an application and continue developing new features of 189 the application for a new version. You then do a release build using ProGuard soon after. The 190 build overwrites the previous <code>mapping.txt</code> file. A user submits a bug report 191 containing a stack trace from the application that is currently published. You no longer have a way 192 of debugging the user's stack trace, because the <code>mapping.txt</code> file associated with the version 193 on the user's device is gone. There are other situations where your <code>mapping.txt</code> file can be overwritten, so 194 ensure that you save a copy for every release that you anticipate you have to debug.</p> 195 196 <p>How you save the <code>mapping.txt</code> file is your decision. For example, you can rename them to 197 include a version or build number, or you can version control them along with your source 198 code.</p> 199