起因：

build.gradle的dependencies加入了

compile 'org.apache.httpcomponents:httpcore:4.3.3'
compile 'org.apache.httpcomponents:httpmime:4.3.6'

在構建時出現以下錯誤log

Information:Gradle tasks [:imagecloud:assembleDebug]
Warning:Dependency org.apache.httpcomponents:httpclient:4.3.6 is ignored for debug as it may be conflicting with the internal version provided by Android.
         In case of problem, please repackage it with jarjar to change the class packages
Warning:Dependency org.apache.httpcomponents:httpclient:4.3.6 is ignored for release as it may be conflicting with the internal version provided by Android.
         In case of problem, please repackage it with jarjar to change the class packages
:imagecloud:preBuild
:imagecloud:compileDebugNdk UP-TO-DATE
:imagecloud:preDebugBuild
:imagecloud:checkDebugManifest
:imagecloud:preReleaseBuild
:imagecloud:prepareComAndroidSupportAppcompatV72103Library UP-TO-DATE
:imagecloud:prepareComAndroidSupportSupportV42103Library UP-TO-DATE
:imagecloud:prepareDebugDependencies
:imagecloud:compileDebugAidl UP-TO-DATE
:imagecloud:compileDebugRenderscript UP-TO-DATE
:imagecloud:generateDebugBuildConfig UP-TO-DATE
:imagecloud:generateDebugAssets UP-TO-DATE
:imagecloud:mergeDebugAssets UP-TO-DATE
:imagecloud:generateDebugResValues UP-TO-DATE
:imagecloud:generateDebugResources UP-TO-DATE
:imagecloud:mergeDebugResources UP-TO-DATE
:imagecloud:processDebugManifest UP-TO-DATE
:imagecloud:processDebugResources UP-TO-DATE
:imagecloud:generateDebugSources UP-TO-DATE
:imagecloud:compileDebugJava UP-TO-DATE
:imagecloud:preDexDebug UP-TO-DATE
:imagecloud:dexDebug UP-TO-DATE
:imagecloud:processDebugJavaRes UP-TO-DATE
:imagecloud:validateDebugSigning
:imagecloud:packageDebug
Error:duplicate files during packaging of APK E:\workspace\project\android\AndroidStudio\imagecloud\build\outputs\apk\imagecloud-debug-unaligned.apk
	Path in archive: META-INF/DEPENDENCIES
	Origin 1: C:\Users\Administrator\.gradle\caches\modules-2\files-2.1\org.apache.httpcomponents\httpmime\4.3.6\cf8bacbf0d476c7f2221f861269365b66447f7ec\httpmime-4.3.6.jar
	Origin 2: C:\Users\Administrator\.gradle\caches\modules-2\files-2.1\org.apache.httpcomponents\httpcore\4.3.3\f91b7a4aadc5cf486df6e4634748d7dd7a73f06d\httpcore-4.3.3.jar
You can ignore those files in your build.gradle:
	android {
	  packagingOptions {
	    exclude 'META-INF/DEPENDENCIES'
	  }
	}
Error:Execution failed for task ':imagecloud:packageDebug'.
> Duplicate files copied in APK META-INF/DEPENDENCIES
	File 1: C:\Users\Administrator\.gradle\caches\modules-2\files-2.1\org.apache.httpcomponents\httpmime\4.3.6\cf8bacbf0d476c7f2221f861269365b66447f7ec\httpmime-4.3.6.jar
	File 2: C:\Users\Administrator\.gradle\caches\modules-2\files-2.1\org.apache.httpcomponents\httpmime\4.3.6\cf8bacbf0d476c7f2221f861269365b66447f7ec\httpmime-4.3.6.jar
Information:BUILD FAILED
Information:Total time: 4.954 secs
Information:2 errors
Information:2 warnings
Information:See complete output in console
 

在build.gradle的android{...}裡面加上

packagingOptions {
        exclude 'META-INF/DEPENDENCIES'
        exclude 'META-INF/NOTICE'
        exclude 'META-INF/LICENSE'
        exclude 'META-INF/LICENSE.txt'
        exclude 'META-INF/NOTICE.txt'
    }