Android: FileNotFoundException using FileInputStream

Question

我正在构建一个FileManager类来处理我的所有文件管理需求。理想情况下，这个FileManager应该完全依赖于Android SDK提供的方法。就正确管理子目录而言，我遇到了一个障碍。当我尝试使用新的FileInputStream对象加载文件时，会遇到FileNotFoundException。如果我尝试使用带有自定义文件路径的context.openFileInput来执行此操作，我会遇到与路径分隔符相关的IllegalArgumentException。

以下是我的writefile和readfile方法。传递给这些方法的所有目录字符串都是内部存储中的子目录（如data/user/0.com.app.package/files/recorations，其中recordings是我创建的子目录）

 /**
 * Writes the provided data to a file based on the designated filename and directory
 * @param data - Array of Strings to be written to the file
 * @param fileName - Relative path of the file being written
 * @param dir - Path of the directory where the file will be written
 * @throws IOException
 */
    private void writeFile(String[] data, String fileName, String dir) throws     IOException {
    Log.v(LOG_TAG, "writeFile");
    if(fileName == null) {
        Log.w(LOG_TAG, "No File Path Provided. File Not Written.");
        return;
    }
    /* Creates and Appends the directory to the provided filename */
    if(dir != null && dir.length() > 0) {
        createDirectory(dir);
        fileName = String.format("%s/%s", dir, fileName);
    }
    /* Opens the Output Stream */
    FileOutputStream fileStream = context.openFileOutput(fileName, Context.MODE_PRIVATE);
    /* Joins String Array into one string to be written to the file */
    String text = TextUtils.join(" ", data);
    /* Writes the String in bytes to the file stream */
    fileStream.write(text.getBytes());
    /* Closes the output stream */
    fileStream.close();
    //This Commented block was part of my previous method of writing files.
    /*
    OutputStreamWriter outputStream = new OutputStreamWriter(fileStream);
    for(int i = 0; i < data.length; i++){
        outputStream.write(data[i]);
        if(i < data.length - 1)
            outputStream.write("n");
    }
    outputStream.close();
    */
}
 /**
 *
 * @param filePath - Relative Filepath of the file being accessed
 * @param dir - Path of the Directory the file can be found in
 * @return - Array of Strings for containing each line of the accessed file.
 * @throws IOException
 */
private String[] readFile(String filePath, String dir) throws IOException {
    Log.v(LOG_TAG, "readFile");
    if(filePath == null)
        return null;
    /* Updates the Filepath with the directory */
    if(dir != null && dir.length() > 0)
        filePath = String.format("%s/%s", dir, filePath);
    String temp;
    ArrayList<String> list = new ArrayList<>();
    /* Initializing Input Stream & Reader */
    FileInputStream fileStream = new FileInputStream(new File(filePath));
    InputStreamReader inputStream = new InputStreamReader(fileStream);
    BufferedReader input = new BufferedReader(inputStream);
    /* Reads Each line into an Array List */
    while((temp = input.readLine()) != null){
        list.add(temp);
    }
    /* Close the Input Streams */
    input.close();
    inputStream.close();
    if(list.size() < 1)
        return null;
    String[] arr = new String[list.size()];
    arr = list.toArray(arr);
    return arr;
}

我需要能够一致地读取、写入和删除内部内存中的文本文件及其包含的目录，我很困惑自己做错了什么，因为我知道这应该相对简单。关于为什么这些方法没有如预期那样表现的一些信息将不胜感激。

Answer 1

在readFile方法中，您可以获得文件路径，我认为它可能看起来像这样：data/user/0/com.app.package/files/recordings/examplefile1.xml和这个路径目录，在这种情况下可能看起来像这样：CCD_ 2。

然后，您将这两个字符串用路径分隔符连接起来。在我的示例中，这将导致以下结果：data/user/0/com.app.package/files/recordings/data/user/0/com.app.package/files/recordings/examplefile1.xml

假设您按如下方式传入目录：data/user/0/com.app.package/files/recordings/该路径将产生以下结果：data/user/0/com.app.package/files/recordings//data/user/0/com.app.package/files/recordings/examplefile1.xml

所以我看到两点

1. 您必须确保filePath参数仅包含文件名
2. 您必须确保在dir参数的末尾已经没有路径分隔符