如何在 android studio 中减小 Apk (.apk) 大小

当我运行我的应用程序时，apk 大小将为 21 MB。即使我启用了混淆器。我使用 android studio 来运行项目。在项目文件中，src 文件夹大小为 8.62 MB，lib 文件夹大小为 400 KB。那么我如何减小 .apk 文件的大小。 实际上，几天前，具有相同图像的 .apk 文件为 8 MB，但在集成 Paypal 后，我的应用程序大小将增加到 21 MB。 构建文件夹的大小为 127 MB。

build.gradle（模块应用程序）是：

apply plugin: 'com.android.application'

android {
    compileSdkVersion 23
    buildToolsVersion "23.0.2"
    useLibrary 'org.apache.http.legacy'
    defaultConfig {
        applicationId "com.oi.food"
        minSdkVersion 16
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

    packagingOptions{
        exclude 'AndroidManifest.xml'
    } }

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.1.1'
    compile files('libs/httpmime-4.1.1.jar')
    compile files('libs/apache-mime4j-0.6.jar')
    compile 'com.squareup.picasso:picasso:2.3.2'
    compile 'com.android.support:design:23.1.1'
    compile 'com.android.support:recyclerview-v7:23.1.1'
    compile 'com.paypal.sdk:paypal-android-sdk:2.14.1' }

我通过在模块应用程序 build.gradle 文件中添加此代码来解决此问题。

 android {
        packagingOptions{
            exclude 'AndroidManifest.xml'
            exclude 'lib/arm64-v8a/libcardioDecider.so'
            exclude 'lib/arm64-v8a/libcardioRecognizer.so'
            exclude 'lib/arm64-v8a/libcardioRecognizer_tegra2.so'
            exclude 'lib/arm64-v8a/libopencv_core.so'
            exclude 'lib/arm64-v8a/libopencv_imgproc.so'
            exclude 'lib/armeabi/libcardioDecider.so'
            exclude 'lib/armeabi-v7a/libcardioDecider.so'
            exclude 'lib/armeabi-v7a/libcardioRecognizer.so'
            exclude 'lib/armeabi-v7a/libcardioRecognizer_tegra2.so'
            exclude 'lib/armeabi-v7a/libopencv_core.so'
            exclude 'lib/armeabi-v7a/libopencv_imgproc.so'
            exclude 'lib/mips/libcardioDecider.so'
            exclude 'lib/x86/libcardioDecider.so'
            exclude 'lib/x86/libcardioRecognizer.so'
            exclude 'lib/x86/libcardioRecognizer_tegra2.so'
            exclude 'lib/x86/libopencv_core.so'
            exclude 'lib/x86/libopencv_imgproc.so'
            exclude 'lib/x86_64/libcardioDecider.so'
            exclude 'lib/x86_64/libcardioRecognizer.so'
            exclude 'lib/x86_64/libcardioRecognizer_tegra2.so'
            exclude 'lib/x86_64/libopencv_core.so'
            exclude 'lib/x86_64/libopencv_imgproc.so'
        }
    }

           dependencies {
            compile fileTree(include: ['*.jar'], dir: 'libs')
            compile 'com.paypal.sdk:paypal-android-sdk:2.14.1'
        }