从android执行shell命令

Question

我正在尝试从应用程序模拟器终端执行此命令（您可以在 google play 中找到它）在这个应用程序中我写 su 并按 enter，所以写：

screenrecord --time-limit 10 /sdcard/MyVideo.mp4

再按一次enter，使用android kitkat的新功能开始录屏。

所以，我尝试使用这个从 java 执行相同的代码：

Process su = Runtime.getRuntime().exec("su");
Process execute = Runtime.getRuntime().exec("screenrecord --time-limit 10 /sdcard/MyVideo.mp4");

但不工作，因为文件没有创建。显然我在安装了 android kitkat 的 root 设备上运行。问题出在哪里？我该如何解决？因为终端模拟器可以工作，而 Java 不行？

Answer 1

您应该获取刚刚启动的su 进程的标准输入并在那里写下命令，否则您正在使用当前UID 运行命令。

试试这样的：

try{
    Process su = Runtime.getRuntime().exec("su");
    DataOutputStream outputStream = new DataOutputStream(su.getOutputStream());

    outputStream.writeBytes("screenrecord --time-limit 10 /sdcard/MyVideo.mp4\n");
    outputStream.flush();

    outputStream.writeBytes("exit\n");
    outputStream.flush();
    su.waitFor();
}catch(IOException e){
    throw new Exception(e);
}catch(InterruptedException e){
    throw new Exception(e);
}

Answer 2

@CarloCannas 对代码的修改：

public static void sudo(String...strings) {
    try{
        Process su = Runtime.getRuntime().exec("su");
        DataOutputStream outputStream = new DataOutputStream(su.getOutputStream());

        for (String s : strings) {
            outputStream.writeBytes(s+"\n");
            outputStream.flush();
        }

        outputStream.writeBytes("exit\n");
        outputStream.flush();
        try {
            su.waitFor();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        outputStream.close();
    }catch(IOException e){
        e.printStackTrace();
    }
}

（欢迎大家为outputStream.close()寻找更好的地方）

使用示例：

private static void suMkdirs(String path) {
    if (!new File(path).isDirectory()) {
        sudo("mkdir -p "+path);
    }
}

更新： 要获得结果（输出到标准输出），请使用：

public static String sudoForResult(String...strings) {
    String res = "";
    DataOutputStream outputStream = null;
    InputStream response = null;
    try{
        Process su = Runtime.getRuntime().exec("su");
        outputStream = new DataOutputStream(su.getOutputStream());
        response = su.getInputStream();

        for (String s : strings) {
            outputStream.writeBytes(s+"\n");
            outputStream.flush();
        }

        outputStream.writeBytes("exit\n");
        outputStream.flush();
        try {
            su.waitFor();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        res = readFully(response);
    } catch (IOException e){
        e.printStackTrace();
    } finally {
        Closer.closeSilently(outputStream, response);
    }
    return res;
}
public static String readFully(InputStream is) throws IOException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    byte[] buffer = new byte[1024];
    int length = 0;
    while ((length = is.read(buffer)) != -1) {
        baos.write(buffer, 0, length);
    }
    return baos.toString("UTF-8");
}

静默关闭多个 Closeables (Soсket may be no Closeable) 的实用程序是：

public class Closer {
// closeAll()
public static void closeSilently(Object... xs) {
    // Note: on Android API levels prior to 19 Socket does not implement Closeable
    for (Object x : xs) {
        if (x != null) {
            try {
                Log.d("closing: "+x);
                if (x instanceof Closeable) {
                    ((Closeable)x).close();
                } else if (x instanceof Socket) {
                    ((Socket)x).close();
                } else if (x instanceof DatagramSocket) {
                    ((DatagramSocket)x).close();
                } else {
                    Log.d("cannot close: "+x);
                    throw new RuntimeException("cannot close "+x);
                }
            } catch (Throwable e) {
                Log.x(e);
            }
        }
    }
}
}

Answer 3

Process p;
StringBuffer output = new StringBuffer();
try {
    p = Runtime.getRuntime().exec(params[0]);
    BufferedReader reader = new BufferedReader(
            new InputStreamReader(p.getInputStream()));
    String line = "";
    while ((line = reader.readLine()) != null) {
        output.append(line + "\n");
        p.waitFor();
    }
} 
catch (IOException e) {
    e.printStackTrace();
} catch (InterruptedException e) {
    e.printStackTrace();
}
String response = output.toString();
return response;