public static void execShellCmd(String cmd) { try { Process process = Runtime.getRuntime().exec("su"); OutputStream outputStream = process.getOutputStream(); DataOutputStream dataOutputStream = new DataOutputStream(outputStream); Log.d(TAG, "[TONY] cmd=" + cmd); dataOutputStream.writeBytes(cmd); dataOutputStream.flush(); dataOutputStream.close(); outputStream.close(); } catch (IOException e) { e.printStackTrace(); }} 这段代码为什么不起作用
时间: 2024-01-07 11:03:44 浏览: 24
这段代码是用于在 Android 设备上执行 shell 命令的。可能有以下几个原因导致它不起作用:
1. 你的设备没有 root 权限,使用 "su" 命令会失败。
2. 你的应用程序没有获取到执行 shell 命令的权限。你需要在 AndroidManifest.xml 文件中添加以下权限:
```xml
<uses-permission android:name="android.permission.ACCESS_SUPERUSER" />
```
3. 某些设备上可能需要使用 "sh" 命令而不是 "su" 命令来获取 root 权限。
4. 某些设备上可能需要在执行命令之前切换到 root 用户,可以尝试在命令执行之前添加以下命令:
```java
process = Runtime.getRuntime().exec("su");
process.waitFor();
```
如果你已经检查了以上原因,仍然无法执行 shell 命令,则需要检查日志以查看是否有其他错误信息。
相关问题
Process process = Runtime.getRuntime().exec("su"); OutputStream outputStream = process.getOutputStream();
这段代码是在 Android 系统上运行的,它的作用是获取 root 权限。`Runtime.getRuntime().exec("su")` 会执行 `su` 命令,如果设备已经 root,会弹出授权请求窗口,用户授权后,程序就会获得 root 权限。然后,通过 `process.getOutputStream()` 方法获取进程的输出流,可以向该进程发送命令,从而进行一些需要 root 权限的操作。需要注意的是,获取 root 权限是一个危险的操作,建议谨慎使用,避免对设备造成损害。
Process process = Runtime.getRuntime().exec(ffmpegCmd);
As an AI language model, I don't have access to the full context of your code. However, I can explain this line of code in general terms.
The line of code creates a new process using the `Runtime` class and the `exec` method. The `exec` method takes a command as a parameter and creates a subprocess to execute that command.
In this particular case, the command is `ffmpegCmd`, which is likely a string containing a command for the FFmpeg library. FFmpeg is a popular open-source multimedia framework that can encode, decode, transcode, and stream audio and video files.
So, this line of code is likely creating a new process to execute an FFmpeg command. The specifics of the command and what the process will do will depend on the code that precedes this line.