JNI with android studio 1.3

Requirements

• Gradle 2.5 only
• Android NDK r10e (if you are using NDK)
• SDK with Build Tools at least version 19.0.0 and we aim to minimize the amount of changes needed for the migration process in the future. Some features may require a more recent version.

Migrating from Traditional Android Gradle Plugin

./gradle/wrapper/gradle-wrapper.properties

The new plugin supports only gradle-2.5.

distributionBase=GRADLE_USER_HOME
distributionPath=wrapper/dists
zipStoreBase=GRADLE_USER_HOME
zipStorePath=wrapper/dists
distributionUrl=https\://services.gradle.org/distributions/gradle-2.5-all.zip

./build.gradle

Classpath for the plugin is com.android.tools.build:gradle-experimental instead of com.android.tools.build:gradle.
The first version is 0.1.0.

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
repositories {
    jcenter()
}
dependencies {
    classpath 'com.android.tools.build:gradle-experimental:0.1.0'

    // NOTE: Do not place your application dependencies here; they belong
    // in the individual module build.gradle files
}
}

./app/build.gradle

There are significant changes to the DSL of the plugin. We understand that many of the changes are frustrating and seem unnecessary, and our goal is to remove some of these current changes to minimize the migration process from the traditional plugin in the future.

DSL Changes:

• Plugin name is com.android.model.application instead of com.android.application. Or use apply plugin: 'com.android.model.library' if you want to create an Android aar library.
• Configuration is wrapped with the model { } block
• Most properties require the = operator
• Adding elements to a Collection should be done using the += operator.

Current DSL Limitations that will hopefully go away:

• buildTypes, productFlavors and signingConfigs must be place outside of the android { } block.
• Nested options within the android { } block must be configured using the with keyword.
  Properties are only set with their direct types only, with no way to accept other types and adapting them. For instance:
• Properties of type File accepts only File instead of File and String objects.
  minSdkVersion cannot directly receive either an integer or string (for codename).
• Creating a buildType or productFlavor requires calling the create method. Modifying an existing one such as the release and debug buildType can be done using the just the name.
• The DSL for modifying variants and their tasks is very, very limited right now.

    apply plugin: 'com.android.model.application'

    model {
        android {
            compileSdkVersion = 22
            buildToolsVersion = "22.0.1"
    
            defaultConfig.with {
                applicationId =  "com.example.user.myapplication"
                minSdkVersion.apiLevel = 15
                targetSdkVersion.apiLevel = 22
                versionCode = 1
                versionName = "1.0"
            }
        }
        android.buildTypes {
            release {
                isMinifyEnabled = false
                proguardFiles += file('proguard-rules.pro')
            }
        }
        android.productFlavors {
            create("flavor1") {
                applicationId = ‘com.app’
            }
        }
    
        // Configures source set directory.
        android.sources {
            main {
                java {
                    source {
                        srcDir 'src'
                    }
                }
            }
        }
    }

    dependencies {
        compile fileTree(dir: 'libs', include: ['*.jar'])
        compile 'com.android.support:appcompat-v7:22.2.0'
    }

Ndk Integration

The experimental plugin comes with NDK integration for creating native applications. To use the NDK integration:

• Use the SDK Manager inside Studio to download the NDK.
• Set ndk.dir in local.properties or the ANDROID_NDK_HOME environment variable to the directory containing the NDK.
• Add an android.ndk block to the model in build.gradle.

Known Limitations

The build.gradle of a simple NDK application may look like this:

apply plugin: 'com.android.model.application'

model {
    android {
        compileSdkVersion = 22
        buildToolsVersion = "22.0.1"
    }
    android.ndk {
        moduleName = "native"
    }
}

Note that the moduleName is required. It determines the name of the resulting native library.

By default, it will look in src/main/jni for C/C++ file. Configure android.sources to change the source directory.

model {
    android {
        compileSdkVersion = 22
        buildToolsVersion = "22.0.1"
    }
    android.ndk {
        moduleName = "native"
    }
    android.sources {
        main {
            jni {
                source {
                    srcDir 'src'
                }
            }
        }
    }
}

Various build options can be set within the android.ndk { } block. For example,

model {
    android {
        compileSdkVersion = 22
        buildToolsVersion = "22.0.1"
    }
    android.ndk {
        // All configurations that can be changed in android.ndk.
        moduleName = "native"
        toolchain = "clang"
        toolchainVersion = "3.5"
        // Note that CFlags has a capital C, which is inconsistent with
        // the naming convention of other properties.  This is a
        // technical limitation that will be resolved
        CFlags += "-DCUSTOM_DEFINE"
        cppFlags += "-DCUSTOM_DEFINE"
        ldFlags += "-L/custom/lib/path"
        ldLibs += "log"
        stl = "stlport_static"
    }
    android.productFlavors {
        create("arm") {
            ndk.with {
                // You can customize the NDK configurations for each
                // productFlavors and buildTypes.
                abiFilters += "armeabi-v7a"
            }
        }
        create("fat") {
            // If ndk.abiFilters is not configured, the application
            // compile and package all suppported ABI.
        }
    }

    // You can modify the NDK configuration for each variant.
    components.android {
        binaries.afterEach { binary ->
            binary.mergedNdkConfig.cppFlags.add(
                    "-DVARIANT=\"" + binary.name + "\"")
        }
    }
}

sample

https://github.com/googlesamples/android-ndk