如何在android studio中侦听来自shell命令的响应? [英] How do I listen for a response from shell command in android studio?

问题描述

在android终端模拟器中，我可以键入以下命令:

In an android terminal emulator I can type the following commands:

> su
> echo $(</sys/class/power_supply/battery/charge_rate)

，根据手机的充电方式，输出将为无"，普通"或涡轮".我希望能够检索此输出并将其作为字符串值存储在我的程序中.

and depending on how the phone is charging the output will be "None", "Normal" or "Turbo". I would like to be able to retrieve this output and store it as a string value in my program.

因此，我对此进行了一些研究，得出的代码如下:

So I've done a little bit of research into this and the code I came up with is as follows:

    String chargeRate = "None";
    try {
        Runtime rt = Runtime.getRuntime();
        Process process = rt.exec("su \"\"echo $(</sys/class/power_supply/battery/charge_rate)");

        BufferedReader stdInput = new BufferedReader(new InputStreamReader(process.getInputStream()));

        if ((chargeRate = stdInput.readLine()) == null)
            chargeRate = "None";
    }
    catch (Exception e) {
        // TODO
    }

这是从许多不同的答案中得出的，我不太确定这是怎么回事.在调试时，我无法越过或越过此行:

This is taken from a number of different answers and I'm not quite sure whats wrong with it. I can't step over or past this line while debugging:

if ((chargeRate = stdInput.readLine()) == null)

调试器到达此行后，立即显示应用程序正在运行"

As soon as the debugger reaches this line it says "The application is running"

推荐答案

更新:解决方案位于 :

UPDATE : Solution is in Unable using Runtime.exec() to execute shell command "echo" in Android Java code :

Runtime.getRuntime.exec()不会直接执行shell命令，它执行带有参数的可执行文件."echo"是一个内置的外壳命令.它实际上是可执行文件sh的参数的一部分使用选项-c.像 ls 这样的命令是实际的可执行文件.你可以在adb shell中使用 type echo 和 type ls 命令查看差异.

Runtime.getRuntime.exec() doesn't execute a shell command directly, it executes an executable with arguments. "echo" is a builtin shell command. It is actually a part of the argument of the executable sh with the option -c. Commands like ls are actual executables. You can use type echo and type ls command in adb shell to see the difference.

最后的代码是:

String[] cmdline = { "sh", "-c", "echo $..." }; 
Runtime.getRuntime().exec(cmdline);

还可以从 Runtime.exec()内部执行

cat ，而无需调用 sh

cat is also executable from within Runtime.exec() without invoking sh

https://www.javaworld.com/article/2071275/when-runtime-exec---won-t.html?page=2 命令是可执行程序

>执行shell命令并获取尽管TextView使用了直接可执行的命令( ls ，请参见上面的更新)，但它在TextView中的输出还是不错的:

The code in Execute shell commands and get output in a TextView is good although it uses a command that is executable directly (ls, see update above) :

try {
        // Executes the command.
        Process process = Runtime.getRuntime().exec("ls -l");

        // 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);
    }

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