What is base64 encoding in android

How to Encode and Decode Image in Base64 in Android?

Here, we are going to make an application of the “Encoding-Decoding” of an image. By making this application we will be able to learn that how we can encode an image in Base64. We will also be decoding our image with help of a button.

Prerequisite:

Attention reader! Don’t stop learning now. Get hold of all the important Java Foundation and Collections concepts with the Fundamentals of Java and Java Collections Course at a student-friendly price and become industry ready. To complete your preparation from learning a language to DS Algo and many more, please refer Complete Interview Preparation Course.

Before proceeding with this application you should be aware of Base64 in java. If you are not aware of it, use Basic Type Base64 Encoding and Decoding in Java.

What we are going to build in this article?

In this application, we will be using two buttons Encode and Decode to perform their respective operations. Moreover, we will be using a textView to display encoded text and finally an imageView to display the decoded image. Note that we are going to implement this application using Java language. A sample video is given below to get an idea about what we are going to do in this article.

Читайте также:  Размер обои рабочий стол для андроид

Step by Step Implementation

Step 1: Creating a new project

  • Open a new project.
  • We will be working on Empty Activity with language as Java. Leave all other options unchanged.
  • You can change the name of the project at your convenience.
  • There will be two default files named activity_main.xml and MainActivity.java.

If you don’t know how to create a new project in Android Studio then you can refer to How to Create/Start a New Project in Android Studio?

Step 2: Navigate to app > Manifests > AndroidManifest.xml file and add the following permission to it

Step 3: Working with the activity_main.xml file

Here we will design the user interface of our application. We will be using the following components for their respective works:

  • TextView – to show the encoded text
  • ImageView – to show the decoded image.
  • Button – to encode or decode the image on click.

Источник

Кодирование и декодирование в формате Base64

Документация

Base64 — это группа схожих binary-to-text encoding схем, которые представляют двоичные данные в ASCII-формате методом перевода в radix-64 представление. Термин Base64 происходит от a specific MIME content transfer encoding.

Кодирование Base64 широко используется в случаях, когда требуется перекодировать двоичные данные для передачи по каналу приспособленному для передачи текстовых данных. Это делается с целью защиты двоичных данных от любых возможных повреждений при передаче. Base64 широко используется во многих приложениях, включая электронную почту (MIME), и при сохранении больших объёмов данных в XML.

В языке JavaScript существуют две функции, для кодирования и декодирования данных в/из формат Base64 соответственно:

Функция atob() декодирует Base64-кодированную строку. В противоположность ей, функция btoa() создаёт Base64 кодированную ASCII строку из «строки» бинарных данных.

Читайте также:  Kingdom two crowns android управление

Обе функции atob() и btoa() работают со строками. Если вам необходимо работать с ArrayBuffers , обратитесь к этому параграфу.

Tools

The «Unicode Problem»

Since DOMString s are 16-bit-encoded strings, in most browsers calling window.btoa on a Unicode string will cause a Character Out Of Range exception if a character exceeds the range of a 8-bit byte (0x00

0xFF). There are two possible methods to solve this problem:

  • the first one is to escape the whole string (with UTF-8, see encodeURIComponent ) and then encode it;
  • the second one is to convert the UTF-16 DOMString to an UTF-8 array of characters and then encode it.

Here are the two possible methods.

Solution #1 – escaping the string before encoding it

To decode the Base64-encoded value back into a String:

Unibabel implements common conversions using this strategy.

Solution #2 – rewrite the DOMs atob() and btoa() using JavaScript’s TypedArray s and UTF-8

Use a TextEncoder polyfill such as TextEncoding (also includes legacy windows, mac, and ISO encodings), TextEncoderLite, combined with a Buffer and a Base64 implementation such as base64-js.

When a native TextEncoder implementation is not available, the most light-weight solution would be to use TextEncoderLite with base64-js. Use the browser implementation when you can.

The following function implements such a strategy. It assumes base64-js imported as

Источник

Читайте также:  Android studio отформатировать код
Оцените статью
data URIsdata URIs, описанные в RFC 2397, позволяют создателям контента встроить в документ маленькие файлы в виде строки (инлайном).Base64Wikipedia article about Base64 encoding.atob() (en-US)Decodes a string of data which has been encoded using base-64 encoding.btoa()Creates a base-64 encoded ASCII string from a «string» of binary data.The «Unicode Problem»In most browsers, calling btoa() on a Unicode string will cause a Character Out Of Range exception. This paragraph shows some solutions.URISchemeList of Mozilla supported URI schemesStringView In this article is published a library of ours whose aims are:
  • creating a C-like interface for strings (i.e. array of characters codes — ArrayBufferView in JavaScript) based upon the JavaScript ArrayBuffer interface,
  • creating a collection of methods for such string-like objects (since now: stringView s) which work strictly on array of numbers rather than on immutable JavaScript strings,
  • working with other Unicode encodings, different from default JavaScript’s UTF-16 DOMString s,