Android Studio(Gradle)解决库依赖冲突问题

最近在调整代码的时候，出现如下问题：

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Cause : com . android . dex . DexException : Multiple dex files define Landroid / support / annotation / AnimRes ;      UNEXPECTED TOP - LEVEL EXCEPTION : com . android . dex . DexException : Multiple dex files define Landroid / support / annotation / AnimRes ;          at com . android . dx . merge . DexMerger . readSortableTypes ( DexMerger . java : 579 )          at com . android . dx . merge . DexMerger . getSortedTypes ( DexMerger . java : 535 )          at com . android . dx . merge . DexMerger . mergeClassDefs ( DexMerger . java : 517 )          at com . android . dx . merge . DexMerger . mergeDexes ( DexMerger . java : 164 )          at com . android . dx . merge . DexMerger . merge ( DexMerger . java : 188 )          at com . android . dx . command . dexer . Main . mergeLibraryDexBuffers ( Main . java : 504 )          at com . android . dx . command . dexer . Main . runMonoDex ( Main . java : 334 )          at com . android . dx . command . dexer . Main . run ( Main . java : 277 )          at com . android . dx . command . dexer . Main . main ( Main . java : 245 )          at com . android . dx . command . Main . main ( Main . java : 106 )

网上查询了一下，找到如下的解决方法：

我们常常用 gradle.build文件导入依赖库，但是有时候库依赖会发生版本冲突或多个模块依赖同一个库的情况，这就引出两个问题，如下：

• 版本冲突时， Gradle会下载多个版本的依赖库吗？
• 当多个模块依赖同一个库时，每个模块都会去下载该依赖库吗？
  为解决这疑问，接下来我们在 Android Studio用 Gradle举个例子：
  gradle.build依赖部分的配置：

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dependencies {      compile 'com.android.support:appcompat-v7:22.2.1'      compile ( 'com.android.support:design:22.2.1' )      compile 'com.shamanland:fonticon:0.1.8'      androidTestCompile 'com.android.support:support-annotations:22.2.1'      androidTestCompile 'com.android.support.test:runner:0.3'      androidTestCompile ( 'com.android.support.test.espresso:espresso-core:2.2' ) }

在文件目录下或 Android Studio的 Terminal下敲 gradlew -q app:dependencies 命令，便有以下输出：

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_debugAndroidTestApk - # # Internal use , do not manually configure # # + -- - com . android . support : support - annotations : 22.2.1 + -- - com . android . support . test : runner : 0.3 |      + -- - com . android . support . test : exposed - instrumentation - api - publish : 0.3 |      + -- - junit : junit : 4.12 |      |      \ -- - org . hamcrest : hamcrest - core : 1.3 |      \ -- - com . android . support : support - annotations : 22.2.0 -> 22.2.1 \ -- - com . android . support . test . espresso : espresso - core : 2.2      + -- - com . android . support . test . espresso : espresso - idling - resource : 2.2      + -- - com . squareup : javawriter : 2.1.1      + -- - javax . inject : javax . inject : 1      + -- - org . hamcrest : hamcrest - library : 1.3      |      \ -- - org . hamcrest : hamcrest - core : 1.3      + -- - com . android . support . test : rules : 0.3      |      \ -- - com . android . support . test : runner : 0.3 ( * )      + -- - org . hamcrest : hamcrest - integration : 1.3      |      \ -- - org . hamcrest : hamcrest - library : 1.3 ( * )      + -- - com . google . code . findbugs : jsr305 : 2.0.1      + -- - javax . annotation : javax . annotation - api : 1.2      \ -- - com . android . support . test : runner : 0.3 ( * )   _debugAndroidTestCompile - # # Internal use , do not manually configure # # + -- - com . android . support : support - annotations : 22.2.1 + -- - com . android . support . test : runner : 0.3 |      + -- - com . android . support . test : exposed - instrumentation - api - publish : 0.3 |      + -- - junit : junit : 4.12 |      |      \ -- - org . hamcrest : hamcrest - core : 1.3 |      \ -- - com . android . support : support - annotations : 22.2.0 -> 22.2.1 \ -- - com . android . support . test . espresso : espresso - core : 2.2      + -- - com . android . support . test . espresso : espresso - idling - resource : 2.2      + -- - com . squareup : javawriter : 2.1.1      + -- - javax . inject : javax . inject : 1      + -- - org . hamcrest : hamcrest - library : 1.3      |      \ -- - org . hamcrest : hamcrest - core : 1.3      + -- - com . android . support . test : rules : 0.3      |      \ -- - com . android . support . test : runner : 0.3 ( * )      + -- - org . hamcrest : hamcrest - integration : 1.3      |      \ -- - org . hamcrest : hamcrest - library : 1.3 ( * )      + -- - com . google . code . findbugs : jsr305 : 2.0.1      + -- - javax . annotation : javax . annotation - api : 1.2      \ -- - com . android . support . test : runner : 0.3 ( * )   _debugApk - # # Internal use , do not manually configure # # + -- - com . android . support : multidex : 1.0.1 + -- - com . android . support : appcompat - v7 : 22.2.1 |      \ -- - com . android . support : support - v4 : 22.2.1 |          \ -- - com . android . support : support - annotations : 22.2.1 + -- - com . android . support : design : 22.2.1 |      + -- - com . android . support : appcompat - v7 : 22.2.1 ( * ) |      \ -- - com . android . support : support - v4 : 22.2.1 ( * ) \ -- - com . shamanland : fonticon : 0.1.8   _debugCompile - # # Internal use , do not manually configure # # + -- - com . android . support : multidex : 1.0.1 + -- - com . android . support : appcompat - v7 : 22.2.1 |      \ -- - com . android . support : support - v4 : 22.2.1 |          \ -- - com . android . support : support - annotations : 22.2.1 + -- - com . android . support : design : 22.2.1 |      + -- - com . android . support : appcompat - v7 : 22.2.1 ( * ) |      \ -- - com . android . support : support - v4 : 22.2.1 ( * ) \ -- - com . shamanland : fonticon : 0.1.8   _debugUnitTestApk - # # Internal use , do not manually configure # # No dependencies   _debugUnitTestCompile - # # Internal use , do not manually configure # # No dependencies   _releaseApk - # # Internal use , do not manually configure # # + -- - com . android . support : multidex : 1.0.1 + -- - com . android . support : appcompat - v7 : 22.2.1 |      \ -- - com . android . support : support - v4 : 22.2.1 |          \ -- - com . android . support : support - annotations : 22.2.1 + -- - com . android . support : design : 22.2.1 |      + -- - com . android . support : appcompat - v7 : 22.2.1 ( * ) |      \ -- - com . android . support : support - v4 : 22.2.1 ( * ) \ -- - com . shamanland : fonticon : 0.1.8   _releaseCompile - # # Internal use , do not manually configure # # + -- - com . android . support : multidex : 1.0.1 + -- - com . android . support : appcompat - v7 : 22.2.1 |      \ -- - com . android . support : support - v4 : 22.2.1 |          \ -- - com . android . support : support - annotations : 22.2.1 + -- - com . android . support : design : 22.2.1 |      + -- - com . android . support : appcompat - v7 : 22.2.1 ( * ) |      \ -- - com . android . support : support - v4 : 22.2.1 ( * ) \ -- - com . shamanland : fonticon : 0.1.8   _releaseUnitTestApk - # # Internal use , do not manually configure # # No dependencies   _releaseUnitTestCompile - # # Internal use , do not manually configure # # No dependencies   androidJacocoAgent - The Jacoco agent to use to get coverage data . \ -- - org . jacoco : org . jacoco . agent : 0.7.4.201502262128   androidJacocoAnt - The Jacoco ant tasks to use to get execute Gradle tasks . \ -- - org . jacoco : org . jacoco . ant : 0.7.4.201502262128      + -- - org . jacoco : org . jacoco . core : 0.7.4.201502262128      |      \ -- - org . ow2 . asm : asm - debug - all : 5.0.1      + -- - org . jacoco : org . jacoco . report : 0.7.4.201502262128      |      + -- - org . jacoco : org . jacoco . core : 0.7.4.201502262128 ( * )      |      \ -- - org . ow2 . asm : asm - debug - all : 5.0.1      \ -- - org . jacoco : org . jacoco . agent : 0.7.4.201502262128   androidTestApk - Classpath packaged with the compiled 'androidTest' classes . No dependencies   androidTestCompile - Classpath for compiling the androidTest sources . + -- - com . android . support : support - annotations : 22.2.1 + -- - com . android . support . test : runner : 0.3 |      + -- - com . android . support . test : exposed - instrumentation - api - publish : 0.3 |      + -- - junit : junit : 4.12 |      |      \ -- - org . hamcrest : hamcrest - core : 1.3 |      \ -- - com . android . support : support - annotations : 22.2.0 -> 22.2.1 \ -- - com . android . support . test . espresso : espresso - core : 2.2      + -- - com . android . support . test . espresso : espresso - idling - resource : 2.2      + -- - com . squareup : javawriter : 2.1.1      + -- - javax . inject : javax . inject : 1      + -- - org . hamcrest : hamcrest - library : 1.3      |      \ -- - org . hamcrest : hamcrest - core : 1.3      + -- - com . android . support . test : rules : 0.3      |      \ -- - com . android . support . test : runner : 0.3 ( * )      + -- - org . hamcrest : hamcrest - integration : 1.3      |      \ -- - org . hamcrest : hamcrest - library : 1.3 ( * )      + -- - com . google . code . findbugs : jsr305 : 2.0.1      + -- - javax . annotation : javax . annotation - api : 1.2      \ -- - com . android . support . test : runner : 0.3 ( * )   androidTestProvided - Classpath for only compiling the androidTest sources . No dependencies   androidTestWearApp - Link to a wear app to embed for object 'androidTest' . No dependencies   apk - Classpath packaged with the compiled 'main' classes . No dependencies   archives - Configuration for archive artifacts . No dependencies   compile - Classpath for compiling the main sources . + -- - com . android . support : appcompat - v7 : 22.2.1 |      \ -- - com . android . support : support - v4 : 22.2.1 |          \ -- - com . android . support : support - annotations : 22.2.1 + -- - com . android . support : design : 22.2.1 |      + -- - com . android . support : appcompat - v7 : 22.2.1 ( * ) |      \ -- - com . android . support : support - v4 : 22.2.1 ( * ) \