Android使用JNI调用C/C++生成的.so库的流程(功能：apk卸载时调用web页面)

注：功能为在apk被卸载时，打开卸载反馈的web页面，其中linux的C代码源自http://www.cnblogs.com/zealotrouge/p/3182617.html，本文流程主要是生成.so流程、加载使用等

（核心功能代码版权是http://www.cnblogs.com/zealotrouge/的热气球所有，本人只是稍加改动）

注2：cygwin、NDK等其他配置请google

1. 在自己的apk中生成用于启动检测卸载的UninstallStatictics.java类

package jp.accessport.gamebox.utils;

import java.lang.reflect.Method;

import android.content.Context;
import android.os.Build;
import android.util.Log;

//被卸载的统计==处理

public class UninstallStatictics {

	//log
	private static final String	TAG = "UninstallStatictics";
	//生成的监听进程的库
	private static final String	S_ObserverLibrary = "observe-uninstall";
	
	//监听进程pid
	private int	m_nObserverProcessPid = -1;
	
	//初始化监听进程：此处无需实现
	private native int	initObserverProcess(String strUserSerial);
	
	//
	static {
		Log.d(TAG, "load observer process lib --> " + S_ObserverLibrary);
		System.loadLibrary(S_ObserverLibrary);
	}
	
	
	//启动后调用，用于启动监听进程
	public void start(Context context){
		//API level小于17，不需要获取userSerialNumber
		if (Build.VERSION.SDK_INT < 17)
			m_nObserverProcessPid = initObserverProcess(null);
		//否则，需要获取userSerialNumber
		else
			m_nObserverProcessPid = initObserverProcess(getUserSerial(context));
	}
	
	
	//由于targetSdkVersion低于17，只能通过反射获取
	//需要添加权限：<uses-permission android:name="android.permission.READ_PHONE_STATE" />
	private String getUserSerial(Context context){
		Object	objUserManager = context.getSystemService("user");
		if (objUserManager == null){
			Log.e(TAG, "userManager not exist!!!");
			return null;
		}

		String	strSN = null;
		try {
			Class<?>	classSP = Class.forName("android.os.SystemProperties");
			Method		methodGet = classSP.getMethod("get", String.class);
			strSN = (String)methodGet.invoke(classSP, "ro.serialno");
		}
		catch (Exception e){
			e.printStackTrace();
		}
		
		return strSN;
	}
}

2. 因为开发环境是Windows、eclipse，所以在eclipse的工程上刷新即可生成对应的.class文件（此处是UninstallStatictics.class），刚开始是为了生成.class使用javac，好一顿折腾，最后还是没生成出来，传说是android、java共用的情况下生成比较麻烦，看来毕竟不是做java的，有些命令==还是不太熟

3. 使用javah命令生成jp_accessport_gamebox_utils_UninstallStatictics.h头文件（命名==是有规则的，不用自己标示名字），因为使用的不是简单类型，而是包含如Context==的android的类库，所以生成过程中产生各种问题，解决方法参见http://blog.csdn.net/hejinjing_tom_com/article/details/8125648

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>

/* Header for class jp_accessport_gamebox_utils_UninstallStatictics */

#ifndef _Included_jp_accessport_gamebox_utils_UninstallStatictics
#define _Included_jp_accessport_gamebox_utils_UninstallStatictics
#ifdef __cplusplus
extern "C" {
#endif

/*
 * Class:     jp_accessport_gamebox_utils_UninstallStatictics
 * Method:    initObserverProcess
 * Signature: (Ljava/lang/String;)I
 */
JNIEXPORT jint JNICALL Java_jp_accessport_gamebox_utils_UninstallStatictics_initObserverProcess
  (JNIEnv *, jobject, jstring);

#ifdef __cplusplus
}
#endif
#endif

4. 生成.h文件后，就可以写代码实现Java_jp_accessport_gamebox_utils_UninstallStatictics_initObserverProcess功能了，我生成的实现类时observe-file.c，没有对应.h文件的名字，因为在生成.so后，就不需要.h文件了，只要有.so的实现即可（且.so的名字也可随意，但内部的函数名不能随意，这个跟native的调用命名相关），代码如下

//注：因为生成.so文件后，所以不再需要对应的jp_accessport_gamebox_utils_UninstallStatictics.h头文件
//所以去掉默认的#include "jp_accessport_gamebox_utils_UninstallStatictics.h"
#include <jni.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/inotify.h>
#include <android/log.h>

//log宏定义
//#define LOG_INFO(tag, msg)		__android_log_write(ANDROID_LOG_INFO, tag, msg)
//#define LOG_DEBUG(tag, msg)		__android_log_write(ANDROID_LOG_DEBUG, tag, msg)
//#define LOG_WARNING(tag, msg)	__android_log_write(ANDROID_LOG_WARNING, tag, msg)
//#define LOG_ERROR(tag, msg)		__android_log_write(ANDROID_LOG_ERROR, tag, msg)

#undef jp_accessport_gamebox_utils_UninstallStatictics_MODE_PRIVATE
#define jp_accessport_gamebox_utils_UninstallStatictics_MODE_PRIVATE 0L
#undef jp_accessport_gamebox_utils_UninstallStatictics_MODE_WORLD_READABLE
#define jp_accessport_gamebox_utils_UninstallStatictics_MODE_WORLD_READABLE 1L
#undef jp_accessport_gamebox_utils_UninstallStatictics_MODE_WORLD_WRITEABLE
#define jp_accessport_gamebox_utils_UninstallStatictics_MODE_WORLD_WRITEABLE 2L
#undef jp_accessport_gamebox_utils_UninstallStatictics_MODE_APPEND
#define jp_accessport_gamebox_utils_UninstallStatictics_MODE_APPEND 32768L
#undef jp_accessport_gamebox_utils_UninstallStatictics_MODE_MULTI_PROCESS
#define jp_accessport_gamebox_utils_UninstallStatictics_MODE_MULTI_PROCESS 4L
#undef jp_accessport_gamebox_utils_UninstallStatictics_BIND_AUTO_CREATE
#define jp_accessport_gamebox_utils_UninstallStatictics_BIND_AUTO_CREATE 1L
#undef jp_accessport_gamebox_utils_UninstallStatictics_BIND_DEBUG_UNBIND
#define jp_accessport_gamebox_utils_UninstallStatictics_BIND_DEBUG_UNBIND 2L
#undef jp_accessport_gamebox_utils_UninstallStatictics_BIND_NOT_FOREGROUND
#define jp_accessport_gamebox_utils_UninstallStatictics_BIND_NOT_FOREGROUND 4L
#undef jp_accessport_gamebox_utils_UninstallStatictics_BIND_ABOVE_CLIENT
#define jp_accessport_gamebox_utils_UninstallStatictics_BIND_ABOVE_CLIENT 8L
#undef jp_accessport_gamebox_utils_UninstallStatictics_BIND_ALLOW_OOM_MANAGEMENT
#define jp_accessport_gamebox_utils_UninstallStatictics_BIND_ALLOW_OOM_MANAGEMENT 16L
#undef jp_accessport_gamebox_utils_UninstallStatictics_BIND_WAIVE_PRIORITY
#define jp_accessport_gamebox_utils_UninstallStatictics_BIND_WAIVE_PRIORITY 32L
#undef jp_accessport_gamebox_utils_UninstallStatictics_BIND_IMPORTANT
#define jp_accessport_gamebox_utils_UninstallStatictics_BIND_IMPORTANT 64L
#undef jp_accessport_gamebox_utils_UninstallStatictics_BIND_ADJUST_WITH_ACTIVITY
#define jp_accessport_gamebox_utils_UninstallStatictics_BIND_ADJUST_WITH_ACTIVITY 128L
#undef jp_accessport_gamebox_utils_UninstallStatictics_CONTEXT_INCLUDE_CODE
#define jp_accessport_gamebox_utils_UninstallStatictics_CONTEXT_INCLUDE_CODE 1L
#undef jp_accessport_gamebox_utils_UninstallStatictics_CONTEXT_IGNORE_SECURITY
#define jp_accessport_gamebox_utils_UninstallStatictics_CONTEXT_IGNORE_SECURITY 2L
#undef jp_accessport_gamebox_utils_UninstallStatictics_CONTEXT_RESTRICTED
#define jp_accessport_gamebox_utils_UninstallStatictics_CONTEXT_RESTRICTED 4L
#undef jp_accessport_gamebox_utils_UninstallStatictics_RESULT_CANCELED
#define jp_accessport_gamebox_utils_UninstallStatictics_RESULT_CANCELED 0L
#undef jp_accessport_gamebox_utils_UninstallStatictics_RESULT_OK
#define jp_accessport_gamebox_utils_UninstallStatictics_RESULT_OK -1L
#undef jp_accessport_gamebox_utils_UninstallStatictics_RESULT_FIRST_USER
#define jp_accessport_gamebox_utils_UninstallStatictics_RESULT_FIRST_USER 1L
#undef jp_accessport_gamebox_utils_UninstallStatictics_DEFAULT_KEYS_DISABLE
#define jp_accessport_gamebox_utils_UninstallStatictics_DEFAULT_KEYS_DISABLE 0L
#undef jp_accessport_gamebox_utils_UninstallStatictics_DEFAULT_KEYS_DIALER
#define jp_accessport_gamebox_utils_UninstallStatictics_DEFAULT_KEYS_DIALER 1L
#undef jp_accessport_gamebox_utils_UninstallStatictics_DEFAULT_KEYS_SHORTCUT
#define jp_accessport_gamebox_utils_UninstallStatictics_DEFAULT_KEYS_SHORTCUT 2L
#undef jp_accessport_gamebox_utils_UninstallStatictics_DEFAULT_KEYS_SEARCH_LOCAL
#define jp_accessport_gamebox_utils_UninstallStatictics_DEFAULT_KEYS_SEARCH_LOCAL 3L
#undef jp_accessport_gamebox_utils_UninstallStatictics_DEFAULT_KEYS_SEARCH_GLOBAL
#define jp_accessport_gamebox_utils_UninstallStatictics_DEFAULT_KEYS_SEARCH_GLOBAL 4L

#ifdef __cplusplus
extern "C" {
#endif


//全局变量
static char		TAG[] = "UninstallStatictics.initObserverProcess";
static jboolean isCopy = JNI_TRUE;

static const char	APP_DIR[] = "/data/data/jp.accessport.gamebox";
static const char	APP_FILES_DIR[] = "/data/data/jp.accessport.gamebox/files";
static const char	APP_OBSERVED_FILE[] = "/data/data/jp.accessport.gamebox/files/observedFile";
static const char	APP_LOCK_FILE[] = "/data/data/jp.accessport.gamebox/files/lockFile";

/************************************************************************/
/* class:	jp_accessport_gamebox_utils_UninstallStatictics
/* method:	initObserverProcess
/* return:	子进程pid
/************************************************************************/
JNIEXPORT jint JNICALL Java_jp_accessport_gamebox_utils_UninstallStatictics_initObserverProcess(JNIEnv *env, jobject obj, jstring userSerial)
{
	jstring	tag = (*env)->NewStringUTF(env, TAG);
//	LOG_DEBUG((*env)->GetStringUTFChars(env, tag, &isCopy)
//				, (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "init observer"), &isCopy));

	//fork子进程，以执行轮询任务
	pid_t	pid = fork();
	if (pid < 0)
	{
//		LOG_ERROR((*env)->GetStringUTFChars(env, tag, &isCopy)
//					, (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "fork failed !!!"), &isCopy));
		exit(1);
	}
	else if (pid == 0)
	{
		//若监听文件所在文件夹不存在，则创建
		FILE*	pFilesDir = fopen(APP_FILES_DIR, "r");
		if (pFilesDir == NULL)
		{
			int	nRet = mkdir(APP_FILES_DIR, S_IRWXU | S_IRWXG | S_IXOTH);
			if (nRet == -1)
			{
//				LOG_ERROR((*env)->GetStringUTFChars(env, tag, &isCopy)
//							, (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "mkdir failed !!!"), &isCopy));
				exit(1);
			}
		}
		fclose(pFilesDir);

		//若被监听文件不存在，则创建文件
		FILE*	pObservedFile = fopen(APP_OBSERVED_FILE, "r");
		if (pObservedFile == NULL)
			pObservedFile = fopen(APP_OBSERVED_FILE, "w");
		fclose(pObservedFile);

		//创建琐文件，通过检查加锁状态来保证只有一个监听进程
		int		nLockFileDescriptor = open(APP_LOCK_FILE, O_RDONLY);
		if (nLockFileDescriptor == -1)
			nLockFileDescriptor = open(APP_LOCK_FILE, O_CREAT);
		int		nLockRet = flock(nLockFileDescriptor, LOCK_EX | LOCK_NB);
		if (nLockRet == -1)
		{
//			LOG_DEBUG((*env)->GetStringUTFChars(env, tag, &isCopy)
//						, (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "observed by another process"), &isCopy));
			exit(0);
		}
//		LOG_DEBUG((*env)->GetStringUTFChars(env, tag, &isCopy)
//					, (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "observed by child process"), &isCopy));

		//分配空间，以便读取event
		void*	pBuf = malloc(sizeof(struct inotify_event));
		if (pBuf == NULL)
		{
//			LOG_ERROR((*env)->GetStringUTFChars(env, tag, &isCopy)
//						, (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "malloc failed !!!"), &isCopy));
			exit(1);
		}

		//分配空间，以便打印mask
		int		nMaskStringLen = 7 + 10 + 1;	//mask=0x占7字节，32位整形数最大为10位，转换为字符串占10字节，'\0'占1字节
		char*	pMaskString = malloc(nMaskStringLen);
		if (pMaskString == NULL)
		{
			if (pBuf != NULL)
			{
				free(pBuf);
				pBuf = NULL;
			}
//			LOG_ERROR((*env)->GetStringUTFChars(env, tag, &isCopy)
//						, (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "malloc failed !!!"), &isCopy));
			exit(1);
		}

		//开始监听
//		LOG_DEBUG((*env)->GetStringUTFChars(env, tag, &isCopy)
//					, (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "start observe"), &isCopy));

		//初始化
		int		nFileDescriptor = inotify_init();
		if (nFileDescriptor < 0)
		{
			if (pMaskString != NULL)
			{
				free(pMaskString);
				pMaskString = NULL;
			}
			if (pBuf != NULL)
			{
				free(pBuf);
				pBuf = NULL;
			}

//			LOG_ERROR((*env)->GetStringUTFChars(env, tag, &isCopy)
//						, (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "inotify_init failed !!!"), &isCopy));
			exit(1);
		}

		//添加被监听文件到监听列表
		int		nWatchDescriptor = inotify_add_watch(nFileDescriptor, APP_OBSERVED_FILE, IN_ALL_EVENTS);
		if (nWatchDescriptor < 0)
		{
			if (pMaskString != NULL)
			{
				free(pMaskString);
				pMaskString = NULL;
			}
			if (pBuf != NULL)
			{
				free(pBuf);
				pBuf = NULL;
			}

//			LOG_ERROR((*env)->GetStringUTFChars(env, tag, &isCopy)
//						, (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "inotify_add_watch failed !!!"), &isCopy));
			exit(1);
		}

		//
		while (1)
		{
			//read会阻塞进程
			size_t	nReadBytes = read(nFileDescriptor, pBuf, sizeof(struct inotify_event));

			//打印mask
			snprintf(pMaskString, nMaskStringLen, "mask=0x%x\0", ((struct inotify_event *)pBuf)->mask);

//			LOG_DEBUG((*env)->GetStringUTFChars(env, tag, &isCopy)
//						, (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, pMaskString), &isCopy));

			//若文件被删除，则可能被卸载，还需进一步判断app文件是否存在
			if (IN_DELETE_SELF == ((struct inotify_event *)pBuf)->mask)
			{
				FILE*	pAppDir = fopen(APP_DIR, "r");
				//确认已卸载
				if (pAppDir == NULL)
				{
					inotify_rm_watch(nFileDescriptor, nWatchDescriptor);
					break;
				}
				//未卸载
				else
				{
					fclose(pAppDir);

					//重新创建监听文件，并重新监听
					FILE*	pObservedFile = fopen(APP_OBSERVED_FILE, "w");
					fclose(pObservedFile);

					nWatchDescriptor = inotify_add_watch(nFileDescriptor, APP_OBSERVED_FILE, IN_ALL_EVENTS);
					if (nWatchDescriptor < 0)
					{
						if (pMaskString != NULL)
						{
							free(pMaskString);
							pMaskString = NULL;
						}
						if (pBuf != NULL)
						{
							free(pBuf);
							pBuf = NULL;
						}

//						LOG_ERROR((*env)->GetStringUTFChars(env, tag, &isCopy)
//									, (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "inotify_add_watch failed !!!"), &isCopy));
						exit(1);
					}
				}
			}
		}

		//释放资源
		if (pMaskString != NULL)
		{
			free(pMaskString);
			pMaskString = NULL;
		}
		if (pBuf != NULL)
		{
			free(pBuf);
			pBuf = NULL;
		}

		//停止监听
//		LOG_DEBUG((*env)->GetStringUTFChars(env, tag, &isCopy)
//					, (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "stop observe"), &isCopy));

		if (userSerial == NULL)
		{
			// 执行命令am start -a android.intent.action.VIEW -d $(url)
			execlp("am", "am", "start", "-a", "android.intent.action.VIEW", "-d", "http://www.so.com", (char *)NULL);
		}
		else
		{
			// 执行命令am start --user userSerial -a android.intent.action.VIEW -d $(url)
			execlp("am", "am", "start", "--user", (*env)->GetStringUTFChars(env, userSerial, &isCopy), "-a", "android.intent.action.VIEW", "-d", "http://www.so.com", (char *)NULL);
		}

		// 执行命令失败log
//		LOG_ERROR((*env)->GetStringUTFChars(env, tag, &isCopy)
//					, (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "exec AM command failed !!!"), &isCopy));
	}
	else
	{
		// 父进程直接退出，使子进程被init进程领养，以避免子进程僵死，同时返回子进程pid
		return pid;
	}
}


#ifdef __cplusplus
}
#endif

5. 为了生成让JNI调用的库文件，在D:\ProgramFiles\android-ndk-r8e\samples\test-jni目录下（本人的ndk安装目录），我copy了份test-jni工程test-jni2，将observe-file.c拷贝到test-jni2\jni\目录下面，修改Android.mk文件如下

# Copyright (C) 2009 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_MODULE    := observe-uninstall	#生成的.so文件的名字，可随意起
LOCAL_SRC_FILES := observe-file.c	#打包编译的文件，此处即是自己生成的用于监控文件是否删除的实现文件

#这个是不能少的，因为observe-file.c中使用了很多的linux的库，此处若不包含，在使用cygwin时编译通不过，就这行，还得我一顿编译不通过啊...
LOCAL_C_INCLUDES := $(LOCAL_PATH)/../../../platforms/android-14/arch-arm/usr/include

LOCAL_EXPORT_LDLIBS:= -llog		#此处忘了哪儿写的了，好像是链接需要的.so库文件

include $(BUILD_SHARED_LIBRARY)
include $(CLEAR_VARS) 

因为我原来是windows下的C++，linux的C编程是真的不熟悉，看到网上关于android的JNI可以调用.dll文件，但反复想过后感觉windows下的api实现，在以linux为基础的android系统中估计不能发挥作用，最后还是硬着头皮整了linux下的.so

另：个人感觉android可以调用.dll主要是指.dll是自己的功能实现，不依赖于系统，否则估计调用不会成功

另2：原来不知道咋搞，找了网上的教程很多，但有的编译不了，有的根本就不行，我连cocos2d-x都实验了，最后还是有问题（说明自己这块是真的不熟悉啊）

6. 使用cygwin，cd到test-jni2目录中：cd /cygdrive/D/ProgramFiles/android-ndk-r8e/samples/test-jni2/，然后使用命令$NDK_ROOT/ndk-build即可进行编译

注1：NDK_ROOT是cygwin的安装目录下D:\ProgramFiles\cygwin\home\gxj\.bash_profile文件的最后添加的执行ndk根目录的变量名，如下面代码的最下面两行的名字，自己也可以修改

# To the extent possible under law, the author(s) have dedicated all 
# copyright and related and neighboring rights to this software to the 
# public domain worldwide. This software is distributed without any warranty. 
# You should have received a copy of the CC0 Public Domain Dedication along 
# with this software. 
# If not, see <http://creativecommons.org/publicdomain/zero/1.0/>. 

# base-files version 4.1-1

# ~/.bash_profile: executed by bash(1) for login shells.

# The latest version as installed by the Cygwin Setup program can
# always be found at /etc/defaults/etc/skel/.bash_profile

# Modifying /etc/skel/.bash_profile directly will prevent
# setup from updating it.

# The copy in your home directory (~/.bash_profile) is yours, please
# feel free to customise it to create a shell
# environment to your liking.  If you feel a change
# would be benifitial to all, please feel free to send
# a patch to the cygwin mailing list.

# User dependent .bash_profile file

# source the users bashrc if it exists
if [ -f "${HOME}/.bashrc" ] ; then
  source "${HOME}/.bashrc"
fi

# Set PATH so it includes user's private bin if it exists
# if [ -d "${HOME}/bin" ] ; then
#   PATH="${HOME}/bin:${PATH}"
# fi

# Set MANPATH so it includes users' private man if it exists
# if [ -d "${HOME}/man" ]; then
#   MANPATH="${HOME}/man:${MANPATH}"
# fi

# Set INFOPATH so it includes users' private info if it exists
# if [ -d "${HOME}/info" ]; then
#   INFOPATH="${HOME}/info:${INFOPATH}"
# fi

NDK_ROOT=/cygdrive/D/ProgramFiles/android-ndk-r8e
export NDK_ROOT

注2：使用编译命令时要使用“$NDK_ROOT/ndk-build”而不是“NDK_ROOT/ndk-build”，之前编译时，因为在光标前有默认的符号“$”，以为编译命令不用输入了，搞了几次都没成功，最后整个copy进去才发现命令“$NDK_ROOT/ndk-build”才有效，无语

7. 编译成功后生成D:\ProgramFiles\android-ndk-r8e\samples\test-jni2\libs\armeabi\libobserve-uninstall.so文件，将libobserve-uninstall.so文件拷贝到自己的apk工程目录E:\Company\Client\Android\GameBox\android_app_gamebox\libs\armeabi\下，注意别直接放在libs下面，要放在libs\armeabi\下面，否则打包.apk时不能打包进去

另：生成的.so的名字是lib+自己的命名，但在android中调用时，若使用System.loadLibrary时，则不要带前面的lib后后边的后缀.so，即System.loadLibrary("observe-uninstall");，当然若是使用System.load，好像得加上全路径了好像，名称也得是全名

8. 刷新编译.apk工程，测试，则可发现在启动自己的apk后，卸载apk则会弹出网页www.so.com，以上