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Base64 Encoding and Decoding in Java with Examples - Java 147

Base64 Encoding and Decoding in Java with Examples – Java 147

Base64 Encoding and Decoding in Java with Examples

使用基本編碼器轉換成 Base64 ，是一種二進位到文字的編碼方案，會取得原始輸入的位元組，並使用字元 A-Z 、 a-z 、 0-9 以及 + 、 / 等，將其編碼，會根據需要在輸出末尾添加一兩個填充字元 (=)，當需要在僅支援文字資料的系統上儲存，或傳輸二進位資料而不遺失或損壞資料時，可以使用 Base64 編碼，Java 8 套件 Base64 類別中提供了一個基本編碼器，可用於將字串編碼為 Base64，並將 Base64 字串解碼為普通字串， Base64 Java Encoding Decoding 本篇增加了範例，並透過單元測試來驗證產出結果。

檔案目錄

./
   +- src
       +- test
       |   +- org
       |       +- ruoxue
       |           +- java_147
       |               +- base64
       |                   +- basic
       |                       +- EncodingDecodingExamplesTest.java

單元測試

Java Encoding Decoding Base64 提供 Base64 基本編碼器操作，將位元組編碼成 Base64 ，並將 Base64 字串解碼為普通字串。

encodeToString

建立一個 String ，轉成 byte[] ，使用 Base64.Encoder 進行編碼。

	@Test
	public void encodeToString() throws Exception {
		Base64.Encoder encoder = Base64.getEncoder();
		String value = "Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484";
		System.out.println(value);
		String result = encoder.encodeToString(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(result);
		assertThat(result).isEqualTo(
				"SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==");
	}
Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484
SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==

decodeWithString

Java Encoding Decoding Base64 建立一個 String ，使用 Base64.Decoder 進行解碼。

	@Test
	public void decodeWithString() throws Exception {
		Base64.Decoder decoder = Base64.getDecoder();
		String value = "SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==";
		System.out.println(value);
		byte[] result = decoder.decode(value);
		System.out.println(result);
		String stringResult = new String(result);
		System.out.println(stringResult);
		assertThat(stringResult).isEqualTo("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
	}
SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==
[B@6aa8ceb6
Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484

encodeWithDst

Java Encoding Decoding Base64 建立一個 String ，轉成 byte[] 使用 Base64.Encoder 進行編碼，將結果存放到另一個陣列。

	@Test
	public void encodeWithDst() throws Exception {
		Base64.Encoder encoder = Base64.getEncoder();
		String value = "Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484";
		System.out.println(value);
		int size = 100;
		byte[] dst = new byte[size];
		int result = encoder.encode(value.getBytes(StandardCharsets.UTF_8.toString()), dst);
		System.out.println(result);
		System.out.println(new String(dst));
		assertThat(new String(dst))
				.containsIgnoringWhitespaces(
						"SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==")
				.hasSize(size);
	}
Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484
92
SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==

decodeWithDst

Java Encoding Decoding Base64 建立一個 String ，轉成 byte[] 使用 Base64.Decoder 進行解碼，將結果存放到另一個陣列。

	@Test
	public void decodeWithDst() throws Exception {
		Base64.Decoder decoder = Base64.getDecoder();
		String value = "SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==";
		System.out.println(value);
		int size = 100;
		byte[] dst = new byte[size];
		int result = decoder.decode(value.getBytes(StandardCharsets.UTF_8.toString()), dst);
		System.out.println(result);
		System.out.println(new String(dst));
		assertThat(new String(dst))
				.containsIgnoringWhitespaces("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484")
				.hasSize(size);
	}
SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==
67
Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484

encodeWithByteBuffer

Base64 Java Encoder Decoder 建立一個 String ，轉成 byte[] 包裝成 ByteBuffer ，使用 Base64.Encoder 進行編碼，傳回 ByteBuffer 。

	@Test
	public void encodeWithByteBuffer() throws Exception {
		Base64.Encoder encoder = Base64.getEncoder();
		String value = "Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484";
		ByteBuffer byteBuffer = ByteBuffer.wrap(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(byteBuffer);
		ByteBuffer result = encoder.encode(byteBuffer);
		System.out.println(result);
		String stringResult = new String(result.array(), StandardCharsets.UTF_8.toString());
		System.out.println(stringResult);
		assertThat(stringResult).isEqualTo(
				"SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==");
	}
java.nio.HeapByteBuffer[pos=0 lim=67 cap=67]
java.nio.HeapByteBuffer[pos=0 lim=92 cap=92]
SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==

decodeWithByteBuffer

Base64 Java Encoder Decoder 建立一個 String ，轉成 byte[] 包裝成 ByteBuffer ，使用 Base64.Decoder 進行解碼，傳回 ByteBuffer 。

	@Test
	public void decodeWithByteBuffer() throws Exception {
		Base64.Decoder decoder = Base64.getDecoder();
		String value = "SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==";
		ByteBuffer byteBuffer = ByteBuffer.wrap(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(byteBuffer);
		ByteBuffer result = decoder.decode(byteBuffer);
		System.out.println(result);
		String stringResult = new String(result.array(), StandardCharsets.UTF_8.toString());
		System.out.println(stringResult);
		assertThat(stringResult).isEqualTo("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
	}	
java.nio.HeapByteBuffer[pos=0 lim=92 cap=92]
java.nio.HeapByteBuffer[pos=0 lim=67 cap=67]
Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484

Base64_encodeBase64String

Base64 Java Encoding and Decoding Example 建立一個 String ，轉成 byte[] 使用 Apache Commons Codec 套件 Base64 進行編碼。

	@Test
	public void Base64_encodeBase64String() throws Exception {
		String value = "Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484";
		System.out.println(value);
		String result = org.apache.commons.codec.binary.Base64
				.encodeBase64String(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(result);
		assertThat(result).isEqualTo(
				"SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==");
	}
Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484
SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==

Base64_decodeBase64WithString

Base64 Java Encoding and Decoding Example 建立一個 String ，使用 Apache Commons Codec 套件 Base64 進行解碼。

	@Test
	public void Base64_decodeBase64WithString() throws Exception {
		String value = "SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==";
		System.out.println(value);
		byte[] result = org.apache.commons.codec.binary.Base64.decodeBase64(value);
		System.out.println(result);
		String stringResult = new String(result);
		System.out.println(stringResult);
		assertThat(stringResult).isEqualTo("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
	}
SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==
[B@6bf2d08e
Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484

EncodingDecodingExamplesTest.java

Base64 Java Encoder Decoder 新增單元測試，驗證 Base64 Java Encoding and Decoding Example 是否符合預期。

package org.ruoxue.java_147.base64.basic;

import static org.assertj.core.api.Assertions.assertThat;

import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;
import java.util.Base64;

import org.junit.Test;

public class EncodingDecodingExamplesTest {

	@Test
	public void encodeToString() throws Exception {
		Base64.Encoder encoder = Base64.getEncoder();
		String value = "Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484";
		System.out.println(value);
		String result = encoder.encodeToString(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(result);
		assertThat(result).isEqualTo(
				"SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==");
	}

	@Test
	public void decodeWithString() throws Exception {
		Base64.Decoder decoder = Base64.getDecoder();
		String value = "SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==";
		System.out.println(value);
		byte[] result = decoder.decode(value);
		System.out.println(result);
		String stringResult = new String(result);
		System.out.println(stringResult);
		assertThat(stringResult).isEqualTo("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
	}

	@Test
	public void encodeWithDst() throws Exception {
		Base64.Encoder encoder = Base64.getEncoder();
		String value = "Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484";
		System.out.println(value);
		int size = 100;
		byte[] dst = new byte[size];
		int result = encoder.encode(value.getBytes(StandardCharsets.UTF_8.toString()), dst);
		System.out.println(result);
		System.out.println(new String(dst));
		assertThat(new String(dst))
				.containsIgnoringWhitespaces(
						"SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==")
				.hasSize(size);
	}

	@Test
	public void decodeWithDst() throws Exception {
		Base64.Decoder decoder = Base64.getDecoder();
		String value = "SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==";
		System.out.println(value);
		int size = 100;
		byte[] dst = new byte[size];
		int result = decoder.decode(value.getBytes(StandardCharsets.UTF_8.toString()), dst);
		System.out.println(result);
		System.out.println(new String(dst));
		assertThat(new String(dst))
				.containsIgnoringWhitespaces("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484")
				.hasSize(size);
	}

	@Test
	public void encodeWithByteBuffer() throws Exception {
		Base64.Encoder encoder = Base64.getEncoder();
		String value = "Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484";
		ByteBuffer byteBuffer = ByteBuffer.wrap(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(byteBuffer);
		ByteBuffer result = encoder.encode(byteBuffer);
		System.out.println(result);
		String stringResult = new String(result.array(), StandardCharsets.UTF_8.toString());
		System.out.println(stringResult);
		assertThat(stringResult).isEqualTo(
				"SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==");
	}

	@Test
	public void decodeWithByteBuffer() throws Exception {
		Base64.Decoder decoder = Base64.getDecoder();
		String value = "SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==";
		ByteBuffer byteBuffer = ByteBuffer.wrap(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(byteBuffer);
		ByteBuffer result = decoder.decode(byteBuffer);
		System.out.println(result);
		String stringResult = new String(result.array(), StandardCharsets.UTF_8.toString());
		System.out.println(stringResult);
		assertThat(stringResult).isEqualTo("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
	}

	@Test
	public void Base64_encodeBase64String() throws Exception {
		String value = "Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484";
		System.out.println(value);
		String result = org.apache.commons.codec.binary.Base64
				.encodeBase64String(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(result);
		assertThat(result).isEqualTo(
				"SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==");
	}

	@Test
	public void Base64_decodeBase64WithString() throws Exception {
		String value = "SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0NjAsIElUIDQ4NA==";
		System.out.println(value);
		byte[] result = org.apache.commons.codec.binary.Base64.decodeBase64(value);
		System.out.println(result);
		String stringResult = new String(result);
		System.out.println(stringResult);
		assertThat(stringResult).isEqualTo("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
	}
}

心得分享

Base64 Java Encoding and Decoding Example 使用基本編碼器，將字串編碼為 Base64，首先將字串轉換為 byte 陣列，然後使用 Base64.Encoder 將 byte 陣列傳給 encode 方法，反之要解碼 Base64 編碼的字串，則使用 Base64.Decoder ，將字串傳給 decode 方法，取得 byte 陣列，提供 Base64 Java Encoder Decoder 工具類別的靜態方法，使用基本編碼器，進行編碼解碼的操作。

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