java - 如何从 SD 卡中获取图像？以及如何转换为字符串（base64）

Question

我需要从 sd 卡访问图像。我有他们的路。我怎样才能将它们转换为基于 64 位的字符串？

Answer 1

做这样的事情......然后，您可以根据需要读取文件。

File dir = Environment.getExternalStorageDirectory();
File yourFile = new File(dir, "path/to/the/file/inside/the/sdcard.ext");

尝试这个。

Answer 2

您可以使用以下代码。

File dir = Environment.getExternalStorageDirectory();
File yourFile = new File(dir, "path/to/the/file/inside/the/sdcard.ext");
String encodeFileToBase64Binary = encodeFileToBase64Binary(yourFile);

private static String encodeFileToBase64Binary(File fileName) throws IOException {
    byte[] bytes = loadFile(fileName);
    byte[] encoded = Base64.encodeBase64(bytes);
    String encodedString = new String(encoded);
    return encodedString;
}

private static byte[] loadFile(File file) throws IOException {
    InputStream is = new FileInputStream(file);

    long length = file.length();
    if (length > Integer.MAX_VALUE) {
        // File is too large
    }
    byte[] bytes = new byte[(int) length];
    int offset = 0;
    int numRead = 0;
    while (offset < bytes.length && (numRead = is.read(bytes, offset, bytes.length - offset)) >= 0) {
        offset += numRead;
    }

    if (offset < bytes.length) {
        throw new IOException("Could not completely read file " + file.getName());
    }

    is.close();
    return bytes;
}