向android studio中导入带有jni的eclipse项目

引入

之前一直是用eclipse做android开发，相对于Google力推的android studio来说，eclipse不仅是个吃内存大户，而且android studio的界面更人性化，除此之外，eclipse对于高分屏并不支持，在笔者的Macbook pro上显得很是粗糙。所以决定把之前在正在eclipse上开发的一个使用NDK开发的android项目转移到android studio上。整个过程很是痛苦，参考了多个博客，终于完成了。记下来，希望能给你有所帮助。

步骤

关于向android studio中导入一般的android项目，请点击这个链接，这篇博客已经说得很好了，我想要说的是如何处理项目中的jni部分。

按照上面的博客导入，如果是一般的android工程，你会发现可以运行成功，但是如果是用NDK开发的native工程，你会发现native c＋＋部分并没有编译，你可以查看libs/armabi/目录下的.so库，你会发现文件的修改日期仍然是你在eclipse上最后编译的日期。

而且android studio不像eclipse，即使ndk环境有误，只要libs/armabi/目录下有编译成功的.so库，eclipse会调用该so库，笔者之前就是抱着这种想法，由于关于jni部分的代码，我并不会再修改，所以就没有配置ndk环境，但是后来发现，如果虽然能编译成功，但是jni部分就和没运行一样，传进去的任何值，返回都是零。

即使配置好了ndk环境，由于你是导入的并非原生在android studio上开发的ndk项目，所以要在根目录下的build.gradle文件中修改些内容。
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’]这时由于在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
    }

上述的src/main/jni是你的jni源码路径。
整个build.gradle应如下面：

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
    }
}