最近要求对安卓平板开发时导出Excel表格到插在平板的U盘上，初步尝试发现，对U盘的文件读写只能操作Android/包名/的目录，不能直接写在根目录，不方便客户使用，于是研究了libaums的库可用是可用，但是调用其device.init() 方法后，就不能在文件管理里面看到U盘了，所以客户使用起来还是不方便，于是想到了Linux文件操作命令。

思路是先生成文件在内置存储卡中，然后使用Linux命令将文件cp或者mv到U盘根目录

复制命令

cp -r srcPath targetPath

剪切命令

mv srcPath targetPath

首先获取U盘的路径，代码如下，有返回值说明有U盘挂载，返回值为空说明U盘未挂载

public static String getUDiskRealPath() {

String filePath = "/proc/mounts";

File file = new File(filePath);

List lineList = new ArrayList<>();

InputStream inputStream =null;

try {

inputStream = new FileInputStream(file);

if (inputStream != null) {

InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "GBK");

BufferedReader bufferedReader = new BufferedReader(inputStreamReader);

String line = "";

while ((line = bufferedReader.readLine()) != null) {

if (line.contains("vfat")) {

lineList.add(line);

}

}

}

} catch (FileNotFoundException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

} finally {

if (inputStream != null) {

try {

inputStream.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

if (lineList.isEmpty()){

Log.i(HEAD, "getUDiskPath no usb disk ");

return "";

}

String editPath = lineList.get(lineList.size() - 1);

Log.i(HEAD,"edit path = " + editPath);

int start = editPath.indexOf("/mnt");

int end = editPath.indexOf(" vfat");

String path = editPath.substring(start, end);

return path;

}

生成你要复制或剪切到U盘的文件并获取其路径srcPath

拼接命令传入下面的执行命令方法中，其中isRooted需传入true

/**

* Execute the command.

*

* @param commands The commands.

* @param isRooted True to use root, false otherwise.

* @param isNeedResultMsg True to return the message of result, false otherwise.

* @return the single {@link CommandResult} instance

*/

public static CommandResult execCmd(final String[] commands,

final boolean isRooted,

final boolean isNeedResultMsg) {

int result = -1;

if (commands == null || commands.length == 0) {

return new CommandResult(result, null, null);

}

Process process = null;

BufferedReader successResult = null;

BufferedReader errorResult = null;

StringBuilder successMsg = null;

StringBuilder errorMsg = null;

DataOutputStream os = null;

try {

process = Runtime.getRuntime().exec(isRooted ? "su" : "sh");

os = new DataOutputStream(process.getOutputStream());

for (String command : commands) {

if (command == null) continue;

os.write(command.getBytes());

os.writeBytes(LINE_SEP);

os.flush();

}

os.writeBytes("exit" + LINE_SEP);

os.flush();

result = process.waitFor();

if (isNeedResultMsg) {

successMsg = new StringBuilder();

errorMsg = new StringBuilder();

successResult = new BufferedReader(new InputStreamReader(process.getInputStream(),

"UTF-8"));

errorResult = new BufferedReader(new InputStreamReader(process.getErrorStream(),

"UTF-8"));

String line;

if ((line = successResult.readLine()) != null) {

successMsg.append(line);

while ((line = successResult.readLine()) != null) {

successMsg.append(LINE_SEP).append(line);

}

}

if ((line = errorResult.readLine()) != null) {

errorMsg.append(line);

while ((line = errorResult.readLine()) != null) {

errorMsg.append(LINE_SEP).append(line);

}

}

}

} catch (Exception e) {

e.printStackTrace();

} finally {

try {

if (os != null) {

os.close();

}

} catch (IOException e) {

e.printStackTrace();

}

try {

if (successResult != null) {

successResult.close();

}

} catch (IOException e) {

e.printStackTrace();

}

try {

if (errorResult != null) {

errorResult.close();

}

} catch (IOException e) {

e.printStackTrace();

}

if (process != null) {

process.destroy();

}

}

return new CommandResult(

result,

successMsg == null ? null : successMsg.toString(),

errorMsg == null ? null : errorMsg.toString()

);

}

例如

/**源文件*/

String srcPath = "/storage/emulated/0/test.txt";

/**目标位置，如U盘跟路径*/

String targetPath = getUDiskRealPath();

/**拼接复制命令*/

String cmd = "cp -r " + srcPath + " " + targetPath;

/**执行复制命令*/

execCmd(new String[]{cmd},true,true);

即可完成文件写在U盘根目录(或者其他目录)的操作。

写文件会了，读文件也就是反过来进行了，先复制或剪切文件到内置存储卡，在进行基本的文件操作即可。

标签：U盘,OTG,new,Android,null,os,line,String

来源： https://blog.csdn.net/Panda_Kill/article/details/106923326