开始活动时将USB拇指驱动器安装到android事物上 [英] Mount USB thumb drive to android things when starting the activity

问题描述

我正在尝试将USB大容量存储设备安装到运行android系统的Raspberry Pi上.我遇到了此答案，该答案说明了如何使用命令行ADB shell进行安装.但是问题是我每次设备启动时都必须运行那些命令.我想将USB驱动器安装在启动活动的 onCreate()中.这是代码:

I am trying to mount the USB mass storage device to my Raspberry Pi running the android things. I came across this answer which shows how to mount it using command line ADB shell. But the problem is I have to run those command every time my device boots. I want to mount the USB drive in onCreate() of my launch activity. Here is the code:

//Here is the mount drive function which I called in onCreate of my activity.

 private void mountDrive() throws IOException, InterruptedException {
        Process mProcess = Runtime.getRuntime().exec("/system/xbin/su");
        BufferedReader reader = new BufferedReader(new InputStreamReader(mProcess.getInputStream()));

        DataOutputStream dos = new DataOutputStream(mProcess.getOutputStream());
        dos.writeBytes("mkdir /mnt/usb\n");
        dos.flush();
        dos.writeBytes("mount -t vfat -o rw /dev/block/sda1 /mnt/usb\n");
        dos.flush();
        dos.writeBytes("exit\n");

        //Read the response
        String line, result = "";
        while ((line = reader.readLine()) != null) {
            result += line;
            Log.d("CMD","RESULT:"+result);
        }
        reader.close();
        dos.flush();
        dos.close();

        mProcess.waitFor();
    }

但是我收到此错误:

I/sh: type=1400 audit(0.0:31): avc: denied { read } for name="/" dev="mmcblk0p6" ino=2 scontext=u:r:untrusted_app:s0:c512,c768 tcontext=u:object_r:rootfs:s0 tclass=dir permissive=1
I/sh: type=1400 audit(0.0:32): avc: denied { open } for path="/" dev="mmcblk0p6" ino=2 scontext=u:r:untrusted_app:s0:c512,c768 tcontext=u:object_r:rootfs:s0 tclass=dir permissive=1
W/System.err: java.io.IOException: Cannot run program "su": error=13, Permission denied
W/System.err:     at java.lang.ProcessBuilder.start(ProcessBuilder.java:983)
W/System.err:     at java.lang.Runtime.exec(Runtime.java:691)
W/System.err:     at java.lang.Runtime.exec(Runtime.java:524)
W/System.err:     at java.lang.Runtime.exec(Runtime.java:421)

如何在我的Android Things中使用我的应用程序挂载USB设备?

How can I mount the USB device using from my application on Android Things?

推荐答案

另一种方法是修改 init.rc 文件.在 init.rc 文件中搜索 on属性:sys.boot_completed = 1 :

An alternative is to modify the init.rc file. Search the init.rc file for on property: sys.boot_completed = 1:

on property: sys.boot_completed = 1
bootchart stop
  # WLD 201805031702
  mkdir / mnt / usb
  chmod 777 / mnt / usb
  exec / system / bin / mount -t vfat / dev / block / sda1 / mnt / usb

#operate only if the pendrive is placed before powering on, if you remove and put it will not work

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