Run native executable in Android App

출처 : http://gimite.net/en/index.php?Run%20native%20executable%20in%20Android%20App

Demo †

Here's demo application called "Run Native Exe" to:

• run local UNIX commands
• run native executable downloaded from the Web

Package: NativeExe-0.2.apk
Source code: on Github (ADT project)

To install the package,

• Go to Settings→Application and check "Unknown sources"
• Open the package link above using Android Browser

or type "adb install NativeExe-*.apk" in your PC if you have Android SDK.

↑

How can I run UNIX commands in Android App? †

You can use Runtime.exec() in standard Java. Here's sample code to run /system/bin/ls /sdcard in Android App:

try {
    // Executes the command.
    Process process = Runtime.getRuntime().exec("/system/bin/ls /sdcard");
    
    // Reads stdout.
    // NOTE: You can write to stdin of the command using
    //       process.getOutputStream().
    BufferedReader reader = new BufferedReader(
            new InputStreamReader(process.getInputStream()));
    int read;
    char[] buffer = new char[4096];
    StringBuffer output = new StringBuffer();
    while ((read = reader.read(buffer)) > 0) {
        output.append(buffer, 0, read);
    }
    reader.close();
    
    // Waits for the command to finish.
    process.waitFor();
    
    return output.toString();
} catch (IOException e) {
    throw new RuntimeException(e);
} catch (InterruptedException e) {
    throw new RuntimeException(e);
}

This code is based on this article. Thanks yussi to let me know this by comment.

↑

OK, but how can I put my own native executable in Android App? †

First, you need to cross-compile your native executable for ARM. Here's a way (dynamic link version). Or you can use Scratchbox (Japanese). If you get a file with a format like this, it's probably OK:

% file yourapp
yourapp: ELF 32-bit LSB executable, ARM, version 1 (SYSV), for GNU/Linux 2.6.14, statically linked, not stripped

You have three ways to put the binary to the phone:

• From Android Java app, using assets folder (by fnerg in comment below)
  • Include the binary in the assets folder.
  • Use getAssets().open("YourBinaryHere") to get an InputStream.
  • Write it to /data/data/app-package-name (e.g. /data/data/net.gimite.nativeexe), where your application has access to write files and make it executable.
  • Run "/system/bin/chmod 744 /data/data/app-package-name/yourapp" using the code above.
  • Run your executable using the code above.

• From Android Java app, downloading via HTTP (which I use in my demo application above)
  • Dowload the executable using HTTP and put it to /data/data/app-package-name (e.g. /data/data/net.gimite.nativeexe), where your application has access to write files and make it executable. You can use standard Java FileOutputStream to write files there.
  • Run "/system/bin/chmod 744 /data/data/app-package-name/yourapp" using the code above.
  • Run your executable using the code above.

• By adb (needs SDK and root)
  • If you want to put the executable to YOUR phone connected with adb command in Android SDK and you have root, you can put the executable by:

    % adb shell
    $ su
    # mkdir /data/tmp
    # chmod 777 /data/tmp
    # exit
    $ exit
    % adb push yourapp /data/tmp
    % adb shell
    $ chmod 744 /data/tmp/yourapp
    $ /data/tmp/yourapp

  • Note that you cannot make files executable in /sdcard.

↑

Old way which no longer works †

This code doesn't work on Android 2.3 (and probably 2.2).

try {
    // android.os.Exec is not included in android.jar so we need to use reflection.
    Class<?> execClass = Class.forName("android.os.Exec");
    Method createSubprocess = execClass.getMethod("createSubprocess",
            String.class, String.class, String.class, int[].class);
    Method waitFor = execClass.getMethod("waitFor", int.class);
    
    // Executes the command.
    // NOTE: createSubprocess() is asynchronous.
    int[] pid = new int[1];
    FileDescriptor fd = (FileDescriptor)createSubprocess.invoke(
            null, "/system/bin/ls", "/sdcard", null, pid);
    
    // Reads stdout.
    // NOTE: You can write to stdin of the command using new FileOutputStream(fd).
    FileInputStream in = new FileInputStream(fd);
    BufferedReader reader = new BufferedReader(new InputStreamReader(in));
    String output = "";
    try {
        String line;
        while ((line = reader.readLine()) != null) {
            output += line + "\n";
        }
    } catch (IOException e) {
        // It seems IOException is thrown when it reaches EOF.
    }
    
    // Waits for the command to finish.
    waitFor.invoke(null, pid[0]);
    
    return output;
} catch (ClassNotFoundException e) {
    throw new RuntimeException(e.getMessage());
} catch (SecurityException e) {
    throw new RuntimeException(e.getMessage());
} catch (NoSuchMethodException e) {
    throw new RuntimeException(e.getMessage());
} catch (IllegalArgumentException e) {
    throw new RuntimeException(e.getMessage());
} catch (IllegalAccessException e) {
    throw new RuntimeException(e.getMessage());
} catch (InvocationTargetException e) {
    throw new RuntimeException(e.getMessage());
}

This code is based on source code of Android Terminal Emulator.