1.通过jni实现函数

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//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)   /* 内全局变量begin */ static char c_TAG [ ] = "onEvent" ; static jboolean b_IS_COPY = JNI_TRUE ;   jstring Java_com_example_uninstallself_Observer_register ( JNIEnv* env ,          jobject thiz , jstring path , jstring url , jint version ) {      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。以运行轮询任务      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 ) {          //子进程注冊文件夹监听器          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 ,                  ( * env ) -> GetStringUTFChars ( env , path , NULL ) , 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 ) ;          }          //開始监听          LOG_DEBUG ( ( * env ) -> GetStringUTFChars ( env , tag , & b_IS_COPY ) ,                  ( * env ) -> GetStringUTFChars ( env ,                          ( * env ) -> NewStringUTF ( env , "start observer" ) ,                          & b_IS_COPY ) ) ;          //read会堵塞进程，          size_t readBytes = read ( fileDescriptor , p_buf ,                  sizeof ( struct inotify_event ) ) ;            //走到这里说明收到文件夹被删除的事件。注销监听器          free ( p_buf ) ;          inotify_rm_watch ( fileDescriptor , IN_DELETE ) ;            //文件夹不存在log          LOG_DEBUG ( ( * env ) -> GetStringUTFChars ( env , tag , & b_IS_COPY ) ,                  ( * env ) -> GetStringUTFChars ( env ,                          ( * env ) -> NewStringUTF ( env , "uninstalled" ) , & b_IS_COPY ) ) ;            if ( version >= 17 ) {              //4.2以上的系统因为用户权限管理更严格，须要加上 --user 0              execlp ( "am" , "am" , "start" , "--user" , "0" , "-a" ,                      "android.intent.action.VIEW" , "-d" ,                      ( * env ) -> GetStringUTFChars ( env , url , NULL ) , ( char * ) NULL ) ;          } else {              execlp ( "am" , "am" , "start" , "-a" , "android.intent.action.VIEW" ,                      "-d" , ( * env ) -> GetStringUTFChars ( env , url , NULL ) ,                      ( char * ) NULL ) ;          }          //扩展：能够运行其它shell命令，am(即activity manager)，能够打开某程序、服务，broadcast intent，等等        } 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      }        return ( * env ) -> NewStringUTF ( env , "Hello from JNI !" ) ; }

2.定义UninstallObserver

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public class UninstallObserver {        static {          System . loadLibrary ( "observer" ) ;      }      /***      *      * @param path 须要监听的文件路径。可用 getApplicationContext().getFilesDir().getPath()      * @param url 卸载调转http      * @param version android.os.Build.VERSION.SDK_INT      * @return      */      public static native String register ( String path , String url , int version ) ; }

3.简单使用

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@ Override protected void onCreate ( Bundle savedInstanceState ) {      super . onCreate ( savedInstanceState ) ;      setContentView ( R . layout . activity_main ) ;        Toast . makeText ( getApplicationContext ( ) ,              getApplicationContext ( ) . getFilesDir ( ) . getPath ( ) + "," + Build . VERSION . SDK_INT , 1 ) . show ( ) ;      long a = System . currentTimeMillis ( ) ;      String str = UninstallObserver . register ( getApplicationContext ( ) . getFilesDir ( ) . getPath ( ) , "http://www.baidu.com" ,              android . os . Build . VERSION . SDK_INT ) ;      long b = System . currentTimeMillis ( ) ;      Toast . makeText ( getApplicationContext ( ) , str + "," + ( b - a ) , 1 ) . show ( ) ;   }