android实现app通过jni调用C/C++方法

本文实现在android app中使用调用jni库调用本地C/C++方法。

1.新建android工程

2.新建java上层方法

本例子在工程中新建 cn.landsem.jnistudy 包，在其中新建TestManager类用于调用本地C/C++方法，该类的代码如下：

package cn.landsem.jnistudy;import android.util.Log;public class TestManager {public static String TAG = "TestManager";static {        try {              System.loadLibrary("lstest");          } catch (Exception e) {        e.printStackTrace();        Log.d(TAG,e.getMessage());        }  Log.d(TAG, "native_init");nativeInit();}public int add(int i,int j) {Log.d(TAG,"add");return nativeAdd(i,j);}private static native void nativeInit();private static native int nativeAdd(int i,int j);}

3.创建jni头文件

打开dos命令窗口，切换到工程目录下的“bin\classes”目录，输入javah -jni cn.landsem.jnistudy.TestManager命令，命令执行成功后会在该目录下生成对应的jni头文件，如本文中完成上述命令会生成 cn_landsem_jnistudy_TestManager.h 文件，文件内容如下：

/* DO NOT EDIT THIS FILE - it is machine generated */#include /* Header for class cn_landsem_jnistudy_TestManager */#ifndef _Included_cn_landsem_jnistudy_TestManager#define _Included_cn_landsem_jnistudy_TestManager#ifdef __cplusplusextern "C" {#endif/* * Class:     cn_landsem_jnistudy_TestManager * Method:    nativeInit * Signature: ()V */JNIEXPORT void JNICALL Java_cn_landsem_jnistudy_TestManager_nativeInit(JNIEnv *, jclass);/* * Class:     cn_landsem_jnistudy_TestManager * Method:    nativeAdd * Signature: (II)I */JNIEXPORT jint JNICALL Java_cn_landsem_jnistudy_TestManager_nativeAdd(JNIEnv *, jclass, jint, jint);#ifdef __cplusplus}#endif#endif

4.新建jni实现

在工程中新建jni目录，将上部操作中生成的jni头文件拷贝到该目录，新建一个c++源文件实现jni中定义的方法，如本文在jni目录下新建cn_landsem_jnistudy_TestManager.cpp文件用于实现上述方法，该方法实现代码如下：

#include "android_runtime/AndroidRuntime.h"#include "JNIHelp.h"#include "jni.h"#include "utils/Log.h"#include "utils/misc.h"#include "cn_landsem_jnistudy_TestManager.h"#include  #include #include #include #include #include #include #define LOG_TAG "Test_JNI"JNIEXPORT void JNICALL Java_cn_landsem_jnistudy_TestManager_nativeInit  (JNIEnv *, jclass)  {ALOGD("call Java_cn_landsem_jnistudy_TestManager_nativeInit");}/* * Class:     cn_landsem_jnistudy_TestManager * Method:    native_add * Signature: (II)I */JNIEXPORT jint JNICALL Java_cn_landsem_jnistudy_TestManager_nativeAdd  (JNIEnv *, jclass, jint, jint) {ALOGD("call Java_cn_landsem_jnistudy_TestManager_nativeAdd");return 0;}

5、生成jni so库

在jni目录下新建Android.mk文件用于编译生成jni库，该文件内容如下：

# Copyright (C) 2010 The Android Open Source Project## Licensed under the Apache License, Version 2.0 (the "License");# you may not use this file except in compliance with the License.# You may obtain a copy of the License at##      http://www.apache.org/licenses/LICENSE-2.0## Unless required by applicable law or agreed to in writing, software# distributed under the License is distributed on an "AS IS" BASIS,# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.# See the License for the specific language governing permissions and# limitations under the License.LOCAL_PATH:= $(call my-dir)include $(CLEAR_VARS)LOCAL_SRC_FILES := cn_landsem_jnistudy_TestManager.cppLOCAL_SHARED_LIBRARIES := \libcutils \libutils \    liblog  \LOCAL_MODULE:= liblstestinclude $(BUILD_SHARED_LIBRARY)

6、包含jni库到工程中

在工程libs目录下新建armeabi目录和armeabi-v7a目录，将生成的jni库放到该目录下。

7、调用

在工程中调用 TestManager 类即可测试。

8、源码下载

源码可以从如下路径下载：http://download.csdn.net/detail/yxtouch/9620436