java - Android:使用 FileInputStream 的 FileNotFoundException

Question

我正在构建一个 FileManager 类来处理我所有的文件管理需求。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，我遇到了障碍。当我尝试使用新的 FileInputStream 对象加载文件时，我遇到了 FileNotFoundException。如果我尝试使用带有自定义文件路径的 context.openFileInput 这样做，我会遇到与我的路径分隔符相关的 IllegalArgumentException。

这是我的 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(例如data/user/0/com.app.package/files/recordings，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、写入和删除文本文件及其包含在内部存储器中的目录，我很困惑我做错了什么，因为我知道这应该相对简单.将不胜感激关于为什么这些方法没有按预期运行的一些信息。

Answer 1

在您的 readFile 方法中，您可以获得文件路径，我认为它可能如下所示:data/user/0/com.app.package/files/recordings/examplefile1.xml和这个路径目录，在这种情况下可能如下所示:data/user/0/com.app.package/files/recordings.

然后将这两个字符串连接起来，中间使用路径分隔符。这将导致在我的示例中出现以下结果: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/此路径将导致以下结果:data/user/0/com.app.package/files/recordings//data/user/0/com.app.package/files/recordings/examplefile1.xml

所以我看到两点

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