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Base64 Encode and Decode in Java with Examples - Java 147

Base64 Encode and Decode in Java with Examples – Java 147

Base64 Encode and Decode in Java with Examples

從 Java 8 以來，已經提供 Base64 編碼器和解碼器，基本、 MIME 和 URL 三種編碼器，將二進位資料可視化，用 64 種字元組合成字串，而這個 Binary 資料和字串資料彼此之間是可以互相轉換的，十分方便，在實際應用上，常用來表示資料加密過後的內容及網路傳輸的內容， Base64 Java Encode Decode 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
       |                   +- EncodeDecodeExamplesTest.java

單元測試

Java Encode Decode 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。

encodeDecode

建立一個 String ，轉成 byte[] ，使用 Base64.Encoder 進行編碼，然後再使用 Base64.Decoder 進行解碼。

	@Test
	public void encodeDecode() throws Exception {
		Base64.Encoder encoder = Base64.getEncoder();
		String value = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
		System.out.println(value);
		String encodedString = encoder.encodeToString(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(encodedString);
		assertThat(encodedString)
				.isEqualTo("QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVphYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ejAxMjM0NTY3ODktXw==");

		Base64.Decoder decoder = Base64.getDecoder();
		byte[] result = decoder.decode(encodedString);
		System.out.println(result);
		System.out.println(new String(result));
		assertThat(new String(result)).isEqualTo("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_");
	}
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_
QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVphYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ejAxMjM0NTY3ODktXw==
[B@1b0375b3
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_

Base64_encodeDecode

Java Encode Decode Base64 建立一個 String ，使用 Apache Commons Codec 套件 Base64 進行編碼，然後再進行解碼。

	@Test
	public void Base64_encodeDecode() throws Exception {
		String value = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
		System.out.println(value);
		byte[] encodedByteArray = org.apache.commons.codec.binary.Base64
				.encodeBase64(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(encodedByteArray);
		System.out.println(new String(encodedByteArray));
		assertThat(new String(encodedByteArray))
				.isEqualTo("QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVphYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ejAxMjM0NTY3ODktXw==");

		byte[] result = org.apache.commons.codec.binary.Base64.decodeBase64(encodedByteArray);
		System.out.println(result);
		System.out.println(new String(result));
		assertThat(new String(result)).isEqualTo("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_");
	}
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_
[B@1a93a7ca
QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVphYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ejAxMjM0NTY3ODktXw==
[B@b684286
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_

mimeEncodeDecode

Java Encode Decode Base64 建立一個 String ，轉成 byte[] ，使用 Base64.MimeEncoder 進行編碼，然後再使用 Base64.MimeDecoder 進行解碼。

	@Test
	public void mimeEncodeDecode() throws Exception {
		Base64.Encoder encoder = Base64.getMimeEncoder();
		StringBuilder value = new StringBuilder();
		value.append("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_");
		System.out.println(value);
		String encodedString = encoder.encodeToString(value.toString().getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(encodedString);
		assertThat(encodedString).containsIgnoringNewLines(
				"QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVphYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ejAxMjM0\n" + "NTY3ODktXw==");

		Base64.Decoder decoder = Base64.getMimeDecoder();
		byte[] result = decoder.decode(encodedString);
		System.out.println(result);
		System.out.println(new String(result));
		assertThat(new String(result)).isEqualTo("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_");
	}
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_
QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVphYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ejAxMjM0
NTY3ODktXw==
[B@7c75222b
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_

Base64_mimeEncodeDecode

Java Encode Decode Base64 建立一個 String ，使用 Apache Commons Codec 套件 Base64 進行編碼，然後再進行解碼。

	@Test
	public void Base64_mimeEncodeDecode() throws Exception {
		StringBuilder value = new StringBuilder();
		value.append("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_");
		System.out.println(value);
		byte[] encodedByteArray = org.apache.commons.codec.binary.Base64
				.encodeBase64Chunked(value.toString().getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(encodedByteArray);
		System.out.println(new String(encodedByteArray));
		assertThat(new String(encodedByteArray)).containsIgnoringNewLines(
				"QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVphYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ejAxMjM0\n" + "NTY3ODktXw==");

		byte[] result = org.apache.commons.codec.binary.Base64.decodeBase64(encodedByteArray);
		System.out.println(result);
		System.out.println(new String(result));
		assertThat(new String(result)).isEqualTo("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_");
	}
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_
[B@1a93a7ca
QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVphYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ejAxMjM0
NTY3ODktXw==

[B@30c7da1e
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_

urlEncodeDecode

Base64 Java Encoder Decoder 建立一個 String ，轉成 byte[] ，使用 Base64.UrlEncoder 進行編碼，然後再使用 Base64.UrlDecoder 進行解碼。

	@Test
	public void urlEncodeDecode() throws Exception {
		Base64.Encoder encoder = Base64.getUrlEncoder();
		String value = "https://www.ruoxue.org/category/rd/java/java-base64/";
		System.out.println(value);
		String encodedString = encoder.encodeToString(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(encodedString);
		assertThat(encodedString).isEqualTo("aHR0cHM6Ly93d3cucnVveHVlLm9yZy9jYXRlZ29yeS9yZC9qYXZhL2phdmEtYmFzZTY0Lw==");

		Base64.Decoder decoder = Base64.getUrlDecoder();
		byte[] result = decoder.decode(encodedString);
		System.out.println(result);
		System.out.println(new String(result));
		assertThat(new String(result)).isEqualTo("https://www.ruoxue.org/category/rd/java/java-base64/");
	}
https://www.ruoxue.org/category/rd/java/java-base64/
aHR0cHM6Ly93d3cucnVveHVlLm9yZy9jYXRlZ29yeS9yZC9qYXZhL2phdmEtYmFzZTY0Lw==
[B@1b0375b3
https://www.ruoxue.org/category/rd/java/java-base64/

Base64_urlEncodeDecode

Base64 Java Encoder Decoder 建立一個 String ，使用 Apache Commons Codec 套件 Base64 進行編碼，然後再進行解碼。

	@Test
	public void Base64_urlEncodeDecode() throws Exception {
		String value = "https://www.ruoxue.org/category/rd/java/java-base64/";
		System.out.println(value);
		byte[] encodedByteArray = org.apache.commons.codec.binary.Base64
				.encodeBase64URLSafe(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(encodedByteArray);
		System.out.println(new String(encodedByteArray));
		assertThat(new String(encodedByteArray))
				.isEqualTo("aHR0cHM6Ly93d3cucnVveHVlLm9yZy9jYXRlZ29yeS9yZC9qYXZhL2phdmEtYmFzZTY0Lw");

		byte[] result = org.apache.commons.codec.binary.Base64.decodeBase64(encodedByteArray);
		System.out.println(result);
		System.out.println(new String(result));
		assertThat(new String(result)).isEqualTo("https://www.ruoxue.org/category/rd/java/java-base64/");
	}
https://www.ruoxue.org/category/rd/java/java-base64/
[B@1a93a7ca
aHR0cHM6Ly93d3cucnVveHVlLm9yZy9jYXRlZ29yeS9yZC9qYXZhL2phdmEtYmFzZTY0Lw
[B@b684286
https://www.ruoxue.org/category/rd/java/java-base64/

EncodeDecodeExamplesTest.java

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

package org.ruoxue.java_147.base64;

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

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

import org.junit.Test;

public class EncodeDecodeExamplesTest {

	@Test
	public void encodeDecode() throws Exception {
		Base64.Encoder encoder = Base64.getEncoder();
		String value = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
		System.out.println(value);
		String encodedString = encoder.encodeToString(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(encodedString);
		assertThat(encodedString)
				.isEqualTo("QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVphYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ejAxMjM0NTY3ODktXw==");

		Base64.Decoder decoder = Base64.getDecoder();
		byte[] result = decoder.decode(encodedString);
		System.out.println(result);
		System.out.println(new String(result));
		assertThat(new String(result)).isEqualTo("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_");
	}

	@Test
	public void Base64_encodeDecode() throws Exception {
		String value = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
		System.out.println(value);
		byte[] encodedByteArray = org.apache.commons.codec.binary.Base64
				.encodeBase64(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(encodedByteArray);
		System.out.println(new String(encodedByteArray));
		assertThat(new String(encodedByteArray))
				.isEqualTo("QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVphYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ejAxMjM0NTY3ODktXw==");

		byte[] result = org.apache.commons.codec.binary.Base64.decodeBase64(encodedByteArray);
		System.out.println(result);
		System.out.println(new String(result));
		assertThat(new String(result)).isEqualTo("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_");
	}

	@Test
	public void mimeEncodeDecode() throws Exception {
		Base64.Encoder encoder = Base64.getMimeEncoder();
		StringBuilder value = new StringBuilder();
		value.append("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_");
		System.out.println(value);
		String encodedString = encoder.encodeToString(value.toString().getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(encodedString);
		assertThat(encodedString).containsIgnoringNewLines(
				"QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVphYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ejAxMjM0\n" + "NTY3ODktXw==");

		Base64.Decoder decoder = Base64.getMimeDecoder();
		byte[] result = decoder.decode(encodedString);
		System.out.println(result);
		System.out.println(new String(result));
		assertThat(new String(result)).isEqualTo("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_");
	}

	@Test
	public void Base64_mimeEncodeDecode() throws Exception {
		StringBuilder value = new StringBuilder();
		value.append("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_");
		System.out.println(value);
		byte[] encodedByteArray = org.apache.commons.codec.binary.Base64
				.encodeBase64Chunked(value.toString().getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(encodedByteArray);
		System.out.println(new String(encodedByteArray));
		assertThat(new String(encodedByteArray)).containsIgnoringNewLines(
				"QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVphYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ejAxMjM0\n" + "NTY3ODktXw==");

		byte[] result = org.apache.commons.codec.binary.Base64.decodeBase64(encodedByteArray);
		System.out.println(result);
		System.out.println(new String(result));
		assertThat(new String(result)).isEqualTo("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_");
	}

	@Test
	public void urlEncodeDecode() throws Exception {
		Base64.Encoder encoder = Base64.getUrlEncoder();
		String value = "https://www.ruoxue.org/category/rd/java/java-base64/";
		System.out.println(value);
		String encodedString = encoder.encodeToString(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(encodedString);
		assertThat(encodedString).isEqualTo("aHR0cHM6Ly93d3cucnVveHVlLm9yZy9jYXRlZ29yeS9yZC9qYXZhL2phdmEtYmFzZTY0Lw==");

		Base64.Decoder decoder = Base64.getUrlDecoder();
		byte[] result = decoder.decode(encodedString);
		System.out.println(result);
		System.out.println(new String(result));
		assertThat(new String(result)).isEqualTo("https://www.ruoxue.org/category/rd/java/java-base64/");
	}

	@Test
	public void Base64_urlEncodeDecode() throws Exception {
		String value = "https://www.ruoxue.org/category/rd/java/java-base64/";
		System.out.println(value);
		byte[] encodedByteArray = org.apache.commons.codec.binary.Base64
				.encodeBase64URLSafe(value.getBytes(StandardCharsets.UTF_8.toString()));
		System.out.println(encodedByteArray);
		System.out.println(new String(encodedByteArray));
		assertThat(new String(encodedByteArray))
				.isEqualTo("aHR0cHM6Ly93d3cucnVveHVlLm9yZy9jYXRlZ29yeS9yZC9qYXZhL2phdmEtYmFzZTY0Lw");

		byte[] result = org.apache.commons.codec.binary.Base64.decodeBase64(encodedByteArray);
		System.out.println(result);
		System.out.println(new String(result));
		assertThat(new String(result)).isEqualTo("https://www.ruoxue.org/category/rd/java/java-base64/");
	}
}

心得分享

Base64 Java Encode and Decode Example 將字串編碼為 Base64，首先將字串轉換為 byte 陣列，然後使用 Encoder 將 byte 陣列傳給 encode 方法，反之要解碼 Base64 編碼的字串，則使用 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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