http://www.cnblogs.com/zealotrouge/p/3159772.html 思路是今天想到了一个Android自API1就有的一个类FileObserver，这个类用于监听某个文件的变化状态，如果是目录，这个类还可以监听其子目录及子目录文件的变化状态，通过阅读FileObserver源码，发现其实现利用了Linux内核中一个重要的机制inotify，它是一个内核用于通知用户空间程序文件系统变化的机制

android_monitor_uninstall.cpp

/* 头文件begin */
#include "main_activity_UninstalledObserverActivity.h"
/* 头文件end */

#ifdef __cplusplus
extern "C" {
#endif

/* 内全局变量begin */
static char c_TAG[] = "UninstalledObserverActivity.init";
static jboolean b_IS_COPY = JNI_TRUE;
/* 内全局变量 */

/*
 * Class:     main_activity_UninstalledObserverActivity
 * Method:    init
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_main_activity_UninstalledObserverActivity_init(JNIEnv *env, jobject obj)
{
    jstring tag = (*env)->NewStringUTF(env, c_TAG);

    //初始化log
    LOG_DEBUG((*env)->GetStringUTFChars(env, tag, &b_IS_COPY)
            , (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "init OK"), &b_IS_COPY));

    //fork子进程，以执行轮询任务
    pid_t pid = fork();
    if (pid < 0)
    {
        //出错log
        LOG_ERROR((*env)->GetStringUTFChars(env, tag, &b_IS_COPY)
                , (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "fork failed !!!"), &b_IS_COPY));
    }
    else if (pid == 0)
    {
        //子进程注册"/data/data/pym.test.uninstalledobserver"目录监听器
        int fileDescriptor = inotify_init();
        if (fileDescriptor < 0)
        {
            LOG_DEBUG((*env)->GetStringUTFChars(env, tag, &b_IS_COPY)
                    , (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "inotify_init failed !!!"), &b_IS_COPY));

             exit(1);
        }

        int watchDescriptor;
        watchDescriptor = inotify_add_watch(fileDescriptor, "/data/data/pym.test.uninstalledobserver", IN_DELETE);
        if (watchDescriptor < 0)
        {
            LOG_DEBUG((*env)->GetStringUTFChars(env, tag, &b_IS_COPY)
                    , (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "inotify_add_watch failed !!!"), &b_IS_COPY));

            exit(1);
        }

        //分配缓存，以便读取event，缓存大小=一个struct inotify_event的大小，这样一次处理一个event
        void *p_buf = malloc(sizeof(struct inotify_event));
        if (p_buf == NULL)
        {
            LOG_DEBUG((*env)->GetStringUTFChars(env, tag, &b_IS_COPY)
                    , (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "malloc failed !!!"), &b_IS_COPY));

            exit(1);
        }
        //开始监听
        LOG_DEBUG((*env)->GetStringUTFChars(env, tag, &b_IS_COPY)
                    , (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "start observer"), &b_IS_COPY));
        size_t readBytes = read(fileDescriptor, p_buf, sizeof(struct inotify_event));

        //read会阻塞进程，走到这里说明收到目录被删除的事件，注销监听器
        free(p_buf);
        inotify_rm_watch(fileDescriptor, IN_DELETE);

        //目录不存在log
        LOG_DEBUG((*env)->GetStringUTFChars(env, tag, &b_IS_COPY)
                    , (*env)->GetStringUTFChars(env, (*env)->NewStringUTF(env, "uninstalled"), &b_IS_COPY));

        //执行命令am start -a android.intent.action.VIEW -d http://shouji.360.cn/web/uninstall/uninstall.html
        execlp("am", "am", "start", "-a", "android.intent.action.VIEW", "-d", "http://shouji.360.cn/web/uninstall/uninstall.html", (char *)NULL);
    }
    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
    }
}

#ifdef __cplusplus
}
#endif

android_monitor_uninstall.h

/* 头文件begin */
#include <jni.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <android/log.h>
#include <unistd.h>
#include <sys/inotify.h>
#include <fcntl.h>
/* 头文件end */

/* 宏定义begin */
//清0宏
#define MEM_ZERO(pDest, destSize) memset(pDest, 0, destSize)

//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_WARN(tag, msg) __android_log_write(ANDROID_LOG_WARN, tag, msg)
#define LOG_ERROR(tag, msg) __android_log_write(ANDROID_LOG_ERROR, tag, msg)
/* 宏定义end */

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

#undef main_activity_UninstalledObserverActivity_MODE_PRIVATE
#define main_activity_UninstalledObserverActivity_MODE_PRIVATE 0L
#undef main_activity_UninstalledObserverActivity_MODE_WORLD_READABLE
#define main_activity_UninstalledObserverActivity_MODE_WORLD_READABLE 1L
#undef main_activity_UninstalledObserverActivity_MODE_WORLD_WRITEABLE
#define main_activity_UninstalledObserverActivity_MODE_WORLD_WRITEABLE 2L
#undef main_activity_UninstalledObserverActivity_MODE_APPEND
#define main_activity_UninstalledObserverActivity_MODE_APPEND 32768L
#undef main_activity_UninstalledObserverActivity_MODE_MULTI_PROCESS
#define main_activity_UninstalledObserverActivity_MODE_MULTI_PROCESS 4L
#undef main_activity_UninstalledObserverActivity_BIND_AUTO_CREATE
#define main_activity_UninstalledObserverActivity_BIND_AUTO_CREATE 1L
#undef main_activity_UninstalledObserverActivity_BIND_DEBUG_UNBIND
#define main_activity_UninstalledObserverActivity_BIND_DEBUG_UNBIND 2L
#undef main_activity_UninstalledObserverActivity_BIND_NOT_FOREGROUND
#define main_activity_UninstalledObserverActivity_BIND_NOT_FOREGROUND 4L
#undef main_activity_UninstalledObserverActivity_BIND_ABOVE_CLIENT
#define main_activity_UninstalledObserverActivity_BIND_ABOVE_CLIENT 8L
#undef main_activity_UninstalledObserverActivity_BIND_ALLOW_OOM_MANAGEMENT
#define main_activity_UninstalledObserverActivity_BIND_ALLOW_OOM_MANAGEMENT 16L
#undef main_activity_UninstalledObserverActivity_BIND_WAIVE_PRIORITY
#define main_activity_UninstalledObserverActivity_BIND_WAIVE_PRIORITY 32L
#undef main_activity_UninstalledObserverActivity_BIND_IMPORTANT
#define main_activity_UninstalledObserverActivity_BIND_IMPORTANT 64L
#undef main_activity_UninstalledObserverActivity_BIND_ADJUST_WITH_ACTIVITY
#define main_activity_UninstalledObserverActivity_BIND_ADJUST_WITH_ACTIVITY 128L
#undef main_activity_UninstalledObserverActivity_CONTEXT_INCLUDE_CODE
#define main_activity_UninstalledObserverActivity_CONTEXT_INCLUDE_CODE 1L
#undef main_activity_UninstalledObserverActivity_CONTEXT_IGNORE_SECURITY
#define main_activity_UninstalledObserverActivity_CONTEXT_IGNORE_SECURITY 2L
#undef main_activity_UninstalledObserverActivity_CONTEXT_RESTRICTED
#define main_activity_UninstalledObserverActivity_CONTEXT_RESTRICTED 4L
#undef main_activity_UninstalledObserverActivity_RESULT_CANCELED
#define main_activity_UninstalledObserverActivity_RESULT_CANCELED 0L
#undef main_activity_UninstalledObserverActivity_RESULT_OK
#define main_activity_UninstalledObserverActivity_RESULT_OK -1L
#undef main_activity_UninstalledObserverActivity_RESULT_FIRST_USER
#define main_activity_UninstalledObserverActivity_RESULT_FIRST_USER 1L
#undef main_activity_UninstalledObserverActivity_DEFAULT_KEYS_DISABLE
#define main_activity_UninstalledObserverActivity_DEFAULT_KEYS_DISABLE 0L
#undef main_activity_UninstalledObserverActivity_DEFAULT_KEYS_DIALER
#define main_activity_UninstalledObserverActivity_DEFAULT_KEYS_DIALER 1L
#undef main_activity_UninstalledObserverActivity_DEFAULT_KEYS_SHORTCUT
#define main_activity_UninstalledObserverActivity_DEFAULT_KEYS_SHORTCUT 2L
#undef main_activity_UninstalledObserverActivity_DEFAULT_KEYS_SEARCH_LOCAL
#define main_activity_UninstalledObserverActivity_DEFAULT_KEYS_SEARCH_LOCAL 3L
#undef main_activity_UninstalledObserverActivity_DEFAULT_KEYS_SEARCH_GLOBAL
#define main_activity_UninstalledObserverActivity_DEFAULT_KEYS_SEARCH_GLOBAL 4L

/*
 * Class:     main_activity_UninstalledObserverActivity
 * Method:    init
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_main_activity_UninstalledObserverActivity_init(JNIEnv *, jobject);

#ifdef __cplusplus
}
#endif
#endif