Question

尝试创建并写入文件，但每次都得到FileNotFoundException，这是我正在使用的方法：

public void saveFileAsPRN(Context context){
    byte[] dataFile = getPrintableFileData();


    String filename = "TestPrn.prn"; 

    // instantiate a file object using the path
    File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), filename);
    Log.e(TAG, Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).toString());

    //determine if the media is mounted with read & write access
    String state = Environment.getExternalStorageState();
    if (Environment.MEDIA_MOUNTED.equals(state)) {
        Log.e(TAG, "media mounted"); //good
    }else{
        Log.e(TAG, "media NOT mounted"); //bad
    }

    //create directory if it does not exist
    //the default Download directory should always exist
    if (!file.mkdirs()) {
        Log.e(TAG, "Directory not created");
    }

    // determine if the file exists, create it if it does not
    if(!file.exists()){
        try {
            Log.e(TAG, "File does not exist, creating..");
            file.createNewFile();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }else{
        Log.e(TAG, "File Exists");
    }    

    //this makes the blank file visible in the file browser
    MediaScannerConnection.scanFile(context, new String[]{Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).toString() + "/" + filename}, null, null);

    //create output stream - send data; saving to file
    OutputStream out = null;
    try {           
        FileOutputStream fos = null;
        fos = new FileOutputStream(file); // <---- CRASHES HERE; FileNotFoundException              
        out = new BufferedOutputStream(fos);
        out.write(dataFile);
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } finally {
        try {
            out.flush();
            out.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }   
}

在以下行引发FileNotFoundException：

fos = new FileOutputStream(file); // <---- CRASHES HERE;

目录存在，并在目标目录中创建一个空白文件（通过浏览PC上的目标文件夹可见）。

调用canWrite()对象上的方法File返回true - 我有写访问权。

清单包含：android.permission.WRITE_EXTERNAL_STORAGE“

所以我没有想法，我看到有几个人有类似的问题，但我找不到答案。

Answer 1

注释掉以下代码修复了问题：

//create directory if it does not exist
//the default Download directory should always exist
if (!file.mkdirs()) {
    Log.e(TAG, "Directory not created");
}

该代码确实创建了一个空白文件，你可以看到它包含在文件夹中，但是 - 这很容易让人误解;你不能对这个文件做任何事情，我试着把它从我的设备转移到我的电脑上，我也无法打开它。并且你无法在代码中打开它的流。

Answer 2

试试这可能对你有帮助。

替换此行

File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), filename);

使用

File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getAbsolutePath(), filename);

FileOutputStream：尝试实例化时的FileNotFoundException

2 个答案: