android.util.Base64OutputStream#write ( )源码实例Demo

/**
 * 
 * @param file
 * @return
 */
public static String fileToBase64(String file) {
    String result= null;
    try {
        FileInputStream fis = new FileInputStream(new File(file));
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        Base64OutputStream base64out = new Base64OutputStream(baos, Base64.NO_WRAP);
        byte[] buffer = new byte[1024];
        int len = 0;
        while ((len = fis.read(buffer)) >= 0) {
            base64out.write(buffer, 0, len);
        }
        base64out.flush();
        base64out.close();
        /*
         * Why should we close Base64OutputStream before processing the data:
         * http://stackoverflow.com/questions/24798745/android-file-to-base64-using-streaming-sometimes-missed-2-bytes
         */
        result = new String(baos.toByteArray(), "UTF-8");
        baos.close();
        fis.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
    return result;
}
 

String convertInputStreamToBase64OutputStream(InputStream is) throws IOException {
  ByteArrayOutputStream baos = new ByteArrayOutputStream();
  Base64OutputStream b64os = new Base64OutputStream(baos, Base64.NO_WRAP);
  byte[] buffer = new byte[BUFFER_SIZE];
  int bytesRead;
  try {
    while ((bytesRead = is.read(buffer)) > -1) {
      b64os.write(buffer, 0, bytesRead);
    }
  } finally {
    closeQuietly(b64os); // this also closes baos and flushes the final content to it
  }
  return baos.toString();
}
 

private void writeToFromStream(OutputStream os, StreamWrapper entry)
        throws IOException {

    // Send the meta data.
    writeMetaData(os, entry.name, entry.contentType);

    int bytesRead;

    // Upload the file's contents in Base64.
    Base64OutputStream bos = new Base64OutputStream(os, Base64.NO_CLOSE | Base64.NO_WRAP);

    // Read from input stream until no more data's left to read.
    while ((bytesRead = entry.inputStream.read(buffer)) != -1) {
        bos.write(buffer, 0, bytesRead);
    }

    // Close the Base64 output stream.
    if (bos != null) {
        bos.close();
    }

    // End the meta data.
    endMetaData(os);

    // Close input stream.
    if (entry.autoClose) {
        // Safely close the input stream.
        if (entry.inputStream != null) {
            entry.inputStream.close();
        }
    }
}
 

private void writeToFromFile(OutputStream os, FileWrapper wrapper)
        throws IOException {

    // Send the meta data.
    writeMetaData(os, wrapper.file.getName(), wrapper.contentType);

    int bytesRead;

    // Open the file for reading.
    FileInputStream in = new FileInputStream(wrapper.file);

    // Upload the file's contents in Base64.
    Base64OutputStream bos = new Base64OutputStream(os, Base64.NO_CLOSE | Base64.NO_WRAP);

    // Read from file until no more data's left to read.
    while ((bytesRead = in.read(buffer)) != -1) {
        bos.write(buffer, 0, bytesRead);
    }

    // Close the Base64 output stream.
    if (bos != null) {
        bos.close();
    }

    // End the meta data.
    endMetaData(os);

    // Safely close the input stream.
    if (in != null) {
        in.close();
    }
}
 

@Override
protected void setUp() throws Exception {
    super.setUp();

    Context context = this.getContext();
    PixateFreestyle.init(context.getApplicationContext());

    // Grab the bitmap placed in the assets. We can use it to compare
    // results later.
    InputStream is = context.getAssets().open(IMAGE_ASSET);
    assetBitmap = BitmapFactory.decodeStream(is);
    is.close();

    Resources resources = context.getResources();

    int rawFileId = resources.getIdentifier(RAW_TEST_FILE, "raw", this.getContext().getPackageName());

    testFileContents = readStream(resources.openRawResource(rawFileId));

    // Create a document file.
    OutputStreamWriter writer =
            new OutputStreamWriter(getContext().openFileOutput(DOCUMENT_FILE, Context.MODE_PRIVATE));
    try {
        writer.write(testFileContents);
    } finally {
        writer.close();
    }

    // Learn the document file's file:// uri so we can test that scheme.
    documentFileUri = new File(context.getFilesDir(), DOCUMENT_FILE).toURI().toString();

    // Clean it up to make it look like someone would type it in css
    // (file:// instead of just file:/)
    if (documentFileUri.startsWith("file:/") && !documentFileUri.startsWith("file://")) {
        documentFileUri = documentFileUri.replace("file:", "file://");
    }

    // Create a temp file.
    tempFile = new File(context.getCacheDir(), TMP_FILE);
    writer = new OutputStreamWriter(new FileOutputStream(tempFile));
    try {
        writer.write(testFileContents);
    } finally {
        writer.close();
    }

    // Get a base64 of the test asset image bytes so we can do a data: call
    // and compare results.
    is = context.getAssets().open(IMAGE_ASSET);
    ByteArrayOutputStream output = new ByteArrayOutputStream();
    Base64OutputStream bos = new Base64OutputStream(output, Base64.DEFAULT);

    try {
        byte[] buffer = new byte[2048];
        int count = is.read(buffer);

        while (count > 0) {
            bos.write(buffer, 0, count);
            count = is.read(buffer);
        }

        assetBitmapBase64 = output.toString();

    } finally {
        is.close();
        bos.close();
    }

}