向android studio中導入帶有jni的eclipse項目

引入

之前一直是用eclipse做android開發，相對于Google力推的android studio來說，eclipse不僅是個吃內存大戶，而且android studio的界面更人性化，除此之外，eclipse對于高分屏并不支持，在筆者的Macbook pro上顯得很是粗糙。所以決定把之前在正在eclipse上開發的一個使用NDK開發的android項目轉移到android studio上。整個過程很是痛苦，參考了多個博客，終于完成了。記下來，希望能給你有所幫助。

步驟

關于向android studio中導入一般的android項目，請點擊這篇博客，這篇博客已經說得很好了，我想要說的是如何處理項目中的jni部分。

按照上面的博客導入，如果是一般的android工程，你會發現可以運行成功，但是如果是用NDK開發的native工程，你會發現native c＋＋部分并沒有編譯，你可以查看libs/armabi/目錄下的.so庫，你會發現文件的修改日期仍然是你在eclipse上最后編譯的日期。

而且android studio不像eclipse，即使ndk環境有誤，只要libs/armabi/目錄下有編譯成功的.so庫，eclipse會調用該so庫，筆者之前就是抱著這種想法，由于關于jni部分的代碼，我并不會再修改，所以就沒有配置ndk環境，但是后來發現，如果雖然能編譯成功，但是jni部分就和沒運行一樣，傳進去的任何值，返回都是零。

即使配置好了ndk環境，由于你是導入的并非原生在android studio上開發的ndk項目，所以要在根目錄下的build.gradle文件中修改些內容。
首先要

sourceSets {
        main {
            manifest.srcFile 'AndroidManifest.xml'
            java.srcDirs = ['src']
            resources.srcDirs = ['src']
            aidl.srcDirs = ['src']
            renderscript.srcDirs = ['src']
            res.srcDirs = ['res']
            assets.srcDirs = ['assets']
            jniLibs.srcDirs = ['libs']
        }

添加jniLibs.srcDirs = [‘libs’]這時由于在android studio中
然后

  task buildNative(type: Exec, description: 'Compile JNI source via NDK') {
        def ndkDir = android.ndkDirectory
        commandLine "$ndkDir/ndk-build",
                '-C', file('/src/main/jni').absolutePath, // Change src/main/jni the relative path to your jni source
                '-j', Runtime.runtime.availableProcessors(),
                'all',
                'NDK_DEBUG=1'
    }


task cleanNative(type: Exec, description: 'Clean JNI object files') {
    def ndkDir = android.ndkDirectory
    commandLine "$ndkDir/ndk-build",
            '-C', file('src/main/jni').absolutePath, // Change src/main/jni the relative path to your jni source
            'clean'
}

clean.dependsOn 'cleanNative'

tasks.withType(JavaCompile) {
    compileTask -> compileTask.dependsOn buildNative
}</pre> 

上述的src/main/jni是你的jni源碼路徑。 

 整個build.gradle應如下面：
buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:1.5.0'
    }
}
apply plugin: 'com.android.application'

dependencies {
    compile fileTree(include: '*.jar', dir: 'libs')
}
android {
    compileSdkVersion 21
    buildToolsVersion '23.0.2'

sourceSets {
    main {
        manifest.srcFile 'AndroidManifest.xml'
        java.srcDirs = ['src']
        resources.srcDirs = ['src']
        aidl.srcDirs = ['src']
        renderscript.srcDirs = ['src']
        res.srcDirs = ['res']
        assets.srcDirs = ['assets']
        jniLibs.srcDirs = ['libs']
    }

    // Move the tests to tests/java, tests/res, etc...
    instrumentTest.setRoot('tests')

    // Move the build types to build-types/<type>
    // For instance, build-types/debug/java, build-types/debug/AndroidManifest.xml, ...
    // This moves them out of them default location under src/<type>/... which would
    // conflict with src/ being used by the main source set.
    // Adding new build types or product flavors should be accompanied
    // by a similar customization.
    debug.setRoot('build-types/debug')
    release.setRoot('build-types/release')
}

task buildNative(type: Exec, description: 'Compile JNI source via NDK') {
    def ndkDir = android.ndkDirectory
    commandLine "$ndkDir/ndk-build",
            '-C', file('src/main/jni').absolutePath, // Change src/main/jni the relative path to your jni source
            '-j', Runtime.runtime.availableProcessors(),
            'all',
            'NDK_DEBUG=1'
}

task cleanNative(type: Exec, description: 'Clean JNI object files') {
    def ndkDir = android.ndkDirectory
    commandLine "$ndkDir/ndk-build",
            '-C', file('src/main/jni').absolutePath, // Change src/main/jni the relative path to your jni source
            'clean'
}

clean.dependsOn 'cleanNative'

tasks.withType(JavaCompile) {
    compileTask -> compileTask.dependsOn buildNative
}

}</pre> </div>