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Вячеслав
Asked:2020-11-28 03:35:00 +0000 UTC2020-11-28 03:35:00 +0000 UTC

将 Json 文件写入和读取到设备内存

  • 772

有两种方法，一种是从服务器下载文件，然后将其写入设备的内存。使用 Fetch 库。第二种方法是读取文件。我不明白我的错误 - 正在创建文件，但是在读取它时，它给出了“”。根据日志，下载正常进行。

private void BookLoader(int bookId) {
    String bookIdJson = "http://****.ru/todbook/book" + bookId + ".json";
    Fetch bFetch;
    String folderJsB = getApplicationContext().getFilesDir().getPath();
    String fileName = "list_"+Uri.parse(bookIdJson).getLastPathSegment();
    Request request = new Request(bookIdJson, folderJsB, fileName);
    bFetch = Fetch.newInstance(getApplicationContext());
    bFetch.removeRequests();
    long resD = bFetch.enqueue(request);
    resD = 0;
}

这是读取方法代码

private String GetJson(String fileListBook) {
    try {
        File f = new File(getApplicationContext().getFilesDir().getPath() + "/" + fileListBook);
        //check whether file exists
        if(!f.exists()){
            return null;
        }
        FileInputStream is = new FileInputStream(f);
        int size = is.available();
        byte[] buffer = new byte[size];
        is.read(buffer);
        is.close();
        return new String(buffer);

    } catch (IOException e) {
        Log.e("TAG", "Error in Reading: " + e.getLocalizedMessage());
        return null;
    }
}
android

2 个回答

  1. Best Answer

    尝试使用此方法读取文件：

    public static String getStringFromFile(String filePath) throws Exception {
        String jString;
        File yourFile = new File(filePath);
        FileInputStream stream = new FileInputStream(yourFile);
        FileChannel fc = stream.getChannel();
        MappedByteBuffer bb = fc.map(FileChannel.MapMode.READ_ONLY, 0, fc.size());
        jString = Charset.defaultCharset().decode(bb).toString();
        stream.close();
        return jString;
    }
    • 1

  2. 读取文件最简单的方法是：

    public static String readTextFromFile(File file) throws IOException {
    StringBuilder result = new StringBuilder();
    BufferedReader br = new BufferedReader(new FileReader(file));
    String line;
    while ((line = br.readLine()) != null) result.append(line).append("\n");
    br.close();
    return result.toString();
}
    • 1

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