Android上执行shell命令的总结

Android提供了两种执行shell命令的方法。

1.Runtime.getRuntime().exec(cmds)

2.ProcessBuilder(cmds)

两种方法背后的逻辑相同。都是创建一个新的进程，执行shell命令。本文以第一种方法为例。代码如下：

public class RuntimeExcUtil {public static int run(String[] fCmds){int tCode=0;mLogger.i("APP_SHELL", "start run");try {Process tProcess = Runtime.getRuntime().exec(fCmds);printError(tProcess);tCode = tProcess.waitFor();mLogger.i("APP_SHELL", "Code Result= "+tCode);} catch (Exception e) {mLogger.e("APP_SHELL", "run Failed, Error Message :"+e.getMessage());}return tCode;}public static int runWithSu(String[] fCmds){int tCode=0;mLogger.i("APP_SHELL", "start run");try {Process tProcess = Runtime.getRuntime().exec("su");runShellScript(tProcess,fCmds);printError(tProcess);tCode = tProcess.waitFor();mLogger.i("APP_SHELL", "Code Result= "+tCode);} catch (Exception e) {mLogger.e("APP_SHELL", "runWithSu Failed, Error Message :"+e.getMessage());}return tCode;}private static void printError(Process fProcess){StringBuilder output = new StringBuilder();String line;try(BufferedReader tReader = new BufferedReader(new InputStreamReader(fProcess.getErrorStream()))) {while ((line = tReader.readLine()) != null) {output.append(line).append("\n");}if (output.toString().length()>0){mLogger.e("APP_SHELL", "Error Output = "+output);}}catch (Exception e){mLogger.e("APP_SHELL", "Print Error Output Failed, Error Message :"+e.getMessage());}}private static void runShellScript(Process fProcess, String[] fCmds){try(DataOutputStream outputStream = new DataOutputStream(fProcess.getOutputStream())) {for (String tCmd :fCmds) {Log.i("APP_SHELL", "Cmd :" + tCmd);outputStream.writeBytes(tCmd + "\n");}outputStream.flush();outputStream.writeBytes("exit\n");outputStream.flush();} catch (Exception e) {Log.e("APP_SHELL", "Run Shell Script Failed, Error Message :"+e.getMessage());}}
}

测试代码如下：

//case 1
RuntimeExcUtil.runWithSu(new String[]{"cp -a -p "+tJavaCrashLogFolderPath+" "+ tCollectFolder});
//case 2
RuntimeExcUtil.runWithSu(new String[]{"cd "+tJavaCrashLogFolderPath,"rm -f crash*"});
//case 3
RuntimeExcUtil.run(new String[]{"cd /sdcard/Download"});
//case 4
RuntimeExcUtil.run(new String[]{"cd", "/sdcard/Download"});
//case 5
RuntimeExcUtil.run(new String[]{"cp -a -p "+tJavaCrashLogFolderPath+" "+ tCollectFolder});
//case 6
RuntimeExcUtil.run(new String[]{"cp", "-a", "-p", tJavaCrashLogFolderPath,tCollectFolder});
//case 7
RuntimeExcUtil.run(new String[]{"rm -f /sdcard/crash/crash*"});
//case 8
RuntimeExcUtil.run(new String[]{"rm", "-f", "/sdcard/crash/crash*"});

Case	结果分析
1	结果：执行成功。原因：创建su窗口，并获取上下文，将后续指令写入 DataOutputStream。不会有权限问题，不会有指令解析问题。
2	结果：同1 原因：同1
3	结果：执行失败。返回Cannot run program "cd /sdcard/Download": error=2, No such file or directory。原因：将整个命令字符串作为一个参数传递给 `RuntimeExcUtil.run()` 方法。这个方法可能会将整个字符串解释为一个可执行程序的名称，而不是将其分解为命令和参数。因此，它会尝试去找一个名为 `cp -a -p /sdcard/crash/ /destination_folder` 的可执行程序。若找不到，则返回No such file or directory。
4	结果：执行失败。返回Cannot run program "cd": error=13, Permission denied。原因：“cd”是用来改变当前工作目录的 shell 命令，并不是一个可执行程序。所以会得到 "Permission denied" 的错误，这是因为 Android 不允许直接执行这种命令。
5	结果：同3 原因：同3
6	结果：执行成功原因：将指令与参数分开，方便解析。
7	结果：同3 原因：同3
8	结果：执行成功原因：将指令与参数分开，方便解析。