本博客是基于Android Studio 1.3 preview版本，且默认你已经安装了Android SDK， Android NDK。
用Android Studio新建一个工程叫AndroidJNI_IntArray，其目录结构如下：
├── AndroidJNI_IntArray.iml
├── app
│ ├── app.iml
│ ├── build
│ ├── build.gradle
│ ├── libs
│ ├── proguard-rules.pro
│ └── src
├── build
│ └── intermediates
├── build.gradle
├── gradle
│ └── wrapper
├── gradle.properties
├── gradlew
├── gradlew.bat
├── local.properties
└── settings.gradle
切换到android视图，可见如下目录：
第一步，编写JNI代码：
1、新建jni文件夹，在jni文件夹下创建logger.h，用来打印输出日志的，其内容如下：
#ifndef ANDROIDJNI_INTARRAY_LOGGER_H #define ANDROIDJNI_INTARRAY_LOGGER_H #include <jni.h> #include <android/log.h> /** * 定义log标签 */ #define TAG "jni_logger" /** * 定义info信息 */ #define LOGI(...) __android_log_print(ANDROID_LOG_INFO, TAG, __VA_ARGS__) /** * 定义debug信息 */ #define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG, TAG, __VA_ARGS__) /** * 定义error信息 */ #define LOGE(...) __android_log_print(ANDROID_LOG_ERROR, TAG, __VA_ARGS__) #endif //ANDROIDJNI_INTARRAY_LOGGER_H
2、接着创建intarray_jni.c主要用来注册绑定java函数和native函数，以及java函数在c中相应函数的具体实现， 内容如下：
#include "logger.h"
#ifndef NULL
#define NULL ((void *) 0)
#endif
/**
* 获取数组大小
*/
#define NELEM(x) ((int)(sizeof(x) / sizeof((x)[0])))
/**
* 指定要注册的类，对应完整的java类名
*/
#define JNIREG_CLASS "com/ndk/clarck/MainActivity"
/**
* 返回数组中元素的和
*/
JNIEXPORT jint JNICALL native_sumArray(JNIEnv *env, jobject obj, jintArray arr) {
jint *carr;
jint i, sum = 0;
carr = (*env)->GetIntArrayElements(env, arr, NULL);
if (carr == NULL) {
return 0;
}
for (i = 0; i < 10; i++) {
sum += carr[i];
}
(*env)->ReleaseIntArrayElements(env, arr, carr, 0);
return sum;
}
/**
* Java和JNI函数绑定
*/
static JNINativeMethod method_table[] = {
{"sumArray", "([I)I", (void *)native_sumArray},
};
/**
* 注册native方法到java中
*/
static int registerNativeMethods(JNIEnv *env, const char* className,
JNINativeMethod* gMethods, int numMethods) {
jclass clazz;
clazz = (*env)->FindClass(env, className);
if (clazz == NULL) {
return JNI_FALSE;
}
if ((*env)->RegisterNatives(env, clazz, gMethods, numMethods) < 0) {
return JNI_FALSE;
}
return JNI_TRUE;
}
/**
* 调用注册方法
*/
int register_ndk_load(JNIEnv *env) {
return registerNativeMethods(env, JNIREG_CLASS, method_table, NELEM(method_table));
}
JNIEXPORT jint JNI_OnLoad(JavaVM *vm, void *reserved) {
JNIEnv *env = NULL;
jint result = -1;
if ((*vm)->GetEnv(vm, (void**)&env, JNI_VERSION_1_4) != JNI_OK) {
return result;
}
register_ndk_load(env);
return JNI_VERSION_1_4;
}
3、java层调用如下：
package com.ndk.clarck;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
int arr[] = new int[10];
for (int i = 0; i < 10; i++) {
arr[i] = i;
}
int sum = sumArray(arr);
Log.d("Test", "sum: " + sum);
}
public native int sumArray(int[] arr);
static {
System.loadLibrary("intarray_jni");
}
}
第二步，配置如下环境，执行编译命令：
1、在local.properties配置SDK和NDK路径如下:
sdk.dir=xxxx
ndk.dir=xxx
2、打开gradle-wrapper.properties，将其配置修改为使用Gradle 2.5来编译(详情参考:http://www.cnblogs.com/tanlon/p/4731283.html)：
#Mon Aug 17 20:34:50 HKT 2015 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
3、配置Project下面的build.gradle，其内容如下：
// 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:0.2.0‘
// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
}
}
allprojects {
repositories {
jcenter()
}
}
4、配置Module下面的build.gradle，其内容如下：
apply plugin: ‘com.android.model.application‘
model {
android {
compileSdkVersion = 22
buildToolsVersion = "22.0.1"
defaultConfig.with {
applicationId = "com.ndk.clarck"
minSdkVersion.apiLevel = 15
targetSdkVersion.apiLevel = 21
}
}
android.ndk {
moduleName = "intarray_jni"
ldLibs += ["log"]
}
android.buildTypes {
release {
minifyEnabled = false
proguardFiles += file(‘proguard-rules.pro‘)
}
}
android.productFlavors {
create ("arm7") {
ndk.abiFilters += "armeabi-v7a"
}
create ("arm8") {
ndk.abiFilters += "arm64-v8a"
}
create ("x86-32") {
ndk.abiFilters += "x86"
}
// for detailed abiFilter descriptions, refer to "Supported ABIs" @
// https://developer.android.com/ndk/guides/abis.html#sa
// build one including all cpu architectures
create("all")
}
}
dependencies {
compile fileTree(dir: ‘libs‘, include: [‘*.jar‘])
compile ‘com.android.support:appcompat-v7:22.2.0‘
}
5、执行Build->Make Project，得到如下输出：
Information:Gradle tasks [:app:assembleAllDebug] :app:copyArm64-v8aDebugAllIntarray_jniSharedLibraryGdbServer UP-TO-DATE :app:createArm64-v8aDebugAllIntarray_jniSharedLibraryGdbsetup :app:compileArm64-v8aDebugAllIntarray_jniSharedLibraryIntarray_jniMainC UP-TO-DATE :app:linkArm64-v8aDebugAllIntarray_jniSharedLibrary UP-TO-DATE :app:stripSymbolsArm64-v8aDebugAllIntarray_jniSharedLibrary UP-TO-DATE :app:arm64-v8aDebugAllIntarray_jniSharedLibrary :app:copyArmeabi-v7aDebugAllIntarray_jniSharedLibraryGdbServer UP-TO-DATE :app:createArmeabi-v7aDebugAllIntarray_jniSharedLibraryGdbsetup :app:compileArmeabi-v7aDebugAllIntarray_jniSharedLibraryIntarray_jniMainC UP-TO-DATE :app:linkArmeabi-v7aDebugAllIntarray_jniSharedLibrary UP-TO-DATE :app:stripSymbolsArmeabi-v7aDebugAllIntarray_jniSharedLibrary UP-TO-DATE :app:armeabi-v7aDebugAllIntarray_jniSharedLibrary :app:copyArmeabiDebugAllIntarray_jniSharedLibraryGdbServer UP-TO-DATE :app:createArmeabiDebugAllIntarray_jniSharedLibraryGdbsetup :app:compileArmeabiDebugAllIntarray_jniSharedLibraryIntarray_jniMainC UP-TO-DATE :app:linkArmeabiDebugAllIntarray_jniSharedLibrary UP-TO-DATE :app:stripSymbolsArmeabiDebugAllIntarray_jniSharedLibrary UP-TO-DATE :app:armeabiDebugAllIntarray_jniSharedLibrary :app:preBuild UP-TO-DATE :app:preAllDebugBuild UP-TO-DATE :app:checkAllDebugManifest :app:preAllReleaseBuild UP-TO-DATE :app:preArm7DebugBuild UP-TO-DATE :app:preArm7ReleaseBuild UP-TO-DATE :app:preArm8DebugBuild UP-TO-DATE :app:preArm8ReleaseBuild UP-TO-DATE :app:preX86-32DebugBuild UP-TO-DATE :app:preX86-32ReleaseBuild UP-TO-DATE :app:prepareComAndroidSupportAppcompatV72220Library UP-TO-DATE :app:prepareComAndroidSupportSupportV42220Library UP-TO-DATE :app:prepareAllDebugDependencies :app:compileAllDebugAidl UP-TO-DATE :app:compileAllDebugRenderscript UP-TO-DATE :app:generateAllDebugBuildConfig UP-TO-DATE :app:generateAllDebugAssets UP-TO-DATE :app:mergeAllDebugAssets UP-TO-DATE :app:generateAllDebugResValues UP-TO-DATE :app:generateAllDebugResources UP-TO-DATE :app:mergeAllDebugResources UP-TO-DATE :app:processAllDebugManifest UP-TO-DATE :app:processAllDebugResources UP-TO-DATE :app:generateAllDebugSources UP-TO-DATE :app:processAllDebugJavaRes UP-TO-DATE :app:compileAllDebugJavaWithJavac :app:copyMips64DebugAllIntarray_jniSharedLibraryGdbServer UP-TO-DATE :app:createMips64DebugAllIntarray_jniSharedLibraryGdbsetup :app:compileMips64DebugAllIntarray_jniSharedLibraryIntarray_jniMainC UP-TO-DATE :app:linkMips64DebugAllIntarray_jniSharedLibrary UP-TO-DATE :app:stripSymbolsMips64DebugAllIntarray_jniSharedLibrary UP-TO-DATE :app:mips64DebugAllIntarray_jniSharedLibrary :app:copyMipsDebugAllIntarray_jniSharedLibraryGdbServer UP-TO-DATE :app:createMipsDebugAllIntarray_jniSharedLibraryGdbsetup :app:compileMipsDebugAllIntarray_jniSharedLibraryIntarray_jniMainC UP-TO-DATE :app:linkMipsDebugAllIntarray_jniSharedLibrary UP-TO-DATE :app:stripSymbolsMipsDebugAllIntarray_jniSharedLibrary UP-TO-DATE :app:mipsDebugAllIntarray_jniSharedLibrary :app:copyX86DebugAllIntarray_jniSharedLibraryGdbServer UP-TO-DATE :app:createX86DebugAllIntarray_jniSharedLibraryGdbsetup :app:compileX86DebugAllIntarray_jniSharedLibraryIntarray_jniMainC UP-TO-DATE :app:linkX86DebugAllIntarray_jniSharedLibrary UP-TO-DATE :app:stripSymbolsX86DebugAllIntarray_jniSharedLibrary UP-TO-DATE :app:x86DebugAllIntarray_jniSharedLibrary :app:copyX86_64DebugAllIntarray_jniSharedLibraryGdbServer UP-TO-DATE :app:createX86_64DebugAllIntarray_jniSharedLibraryGdbsetup :app:compileX86_64DebugAllIntarray_jniSharedLibraryIntarray_jniMainC UP-TO-DATE :app:linkX86_64DebugAllIntarray_jniSharedLibrary UP-TO-DATE :app:stripSymbolsX86_64DebugAllIntarray_jniSharedLibrary UP-TO-DATE :app:x86_64DebugAllIntarray_jniSharedLibrary :app:compileAllDebugSources :app:preDexAllDebug UP-TO-DATE :app:dexAllDebug :app:validateDebugSigning :app:packageAllDebug :app:zipalignAllDebug :app:assembleAllDebug Information:BUILD SUCCESSFUL Information:Total time: 2.772 secs Information:0 errors Information:0 warnings Information:See complete output in console
6、执行Run，即可运行项目了。
经验：
Error:Cause: com.android.build.gradle.managed.AndroidConfig Impl 原因：
defaultConfig 必须写成 defaultConfig.with
时间： 2024-10-07 10:23:58