從 Java 8 開始，已經包含使用 Base64 編碼的內建編碼器和解碼器套件，其中之一 MIME 編碼器，會將輸出映射到 A-Za-z0-9+/ 中的一組字元，如果編碼的資料超過 76 個字元，則會資料將拆分為多行，每行最多包含 76 個字元，添加行分隔符號 \r\n ，輸出末尾不存在行分隔符號，將忽略所有在 Base64 字母表中，找不到的行分隔符號或其他字元，同時也使用 Apache Commons Codec 的實用 API 進行編解碼， MIME Encoding and Decoding in Java 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
| +- mime
| +- MIMEEncodingDecodingTest.java 單元測試
Java MIME Encoder Decoder 提供 Base64 MIME 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。
encode
建立一個 String ，轉成 byte[] ，使用 Base64.MimeEncoder 進行編碼。
@Test
public void encode() throws Exception {
Base64.Encoder encoder = Base64.getMimeEncoder();
StringBuilder value = new StringBuilder();
value.append("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
System.out.println(value);
byte[] result = encoder.encode(value.toString().getBytes(StandardCharsets.UTF_8.toString()));
System.out.println(result);
System.out.println(new String(result));
assertThat(new String(result)).containsIgnoringNewLines(
"SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0\n" + "NjAsIElUIDQ4NA==");
}Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484
[B@6aa8ceb6
SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0
NjAsIElUIDQ4NA==decode
Java MIME Encoder Decoder 建立一個 String ，轉成 byte[] ，使用 Base64.MimeDecoder 進行解碼。
@Test
public void decode() throws Exception {
Base64.Decoder decoder = Base64.getMimeDecoder();
String value = "SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0\n"
+ "NjAsIElUIDQ4NA==";
System.out.println(value);
byte[] result = decoder.decode(value.toString().getBytes(StandardCharsets.UTF_8.toString()));
System.out.println(result);
System.out.println(new String(result));
assertThat(new String(result)).isEqualTo("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
}SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0
NjAsIElUIDQ4NA==
[B@6aa8ceb6
Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484Base64_encodeBase64Chunked
Java MIME Encoder Decoder 建立一個 String ，轉成 byte[] 使用 Apache Commons Codec 套件 Base64 進行編碼。
@Test
public void Base64_encodeBase64Chunked() throws Exception {
StringBuilder value = new StringBuilder();
value.append("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
System.out.println(value);
byte[] result = org.apache.commons.codec.binary.Base64
.encodeBase64Chunked(value.toString().getBytes(StandardCharsets.UTF_8.toString()));
System.out.println(result);
System.out.println(new String(result));
assertThat(new String(result)).containsIgnoringNewLines(
"SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0\n" + "NjAsIElUIDQ4NA==");
}
Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484
[B@4c98385c
SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0
NjAsIElUIDQ4NA==Base64_decodeBase64
建立一個 String ，轉成 byte[] 使用 Apache Commons Codec 套件 Base64 進行解碼。
@Test
public void Base64_decodeBase64() throws Exception {
String value = "SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0\n"
+ "NjAsIElUIDQ4NA==";
System.out.println(value);
byte[] result = org.apache.commons.codec.binary.Base64
.decodeBase64(value.getBytes(StandardCharsets.UTF_8.toString()));
System.out.println(result);
System.out.println(new String(result));
assertThat(new String(result)).isEqualTo("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
}SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0
NjAsIElUIDQ4NA==
[B@4c98385c
Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484Base64_decodeBase64WithString
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 = "SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0\n"
+ "NjAsIElUIDQ4NA==";
System.out.println(value);
byte[] result = org.apache.commons.codec.binary.Base64.decodeBase64(value);
System.out.println(result);
System.out.println(new String(result));
assertThat(new String(result)).isEqualTo("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
}SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0
NjAsIElUIDQ4NA==
[B@6bf2d08e
Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484
MimeEncodingDecodingTest.java
MIME Encoder Decoder in Java 新增單元測試，驗證 Java MIME Encoding Decoding 是否符合預期。
package org.ruoxue.java_147.base64.mime;
import static org.assertj.core.api.Assertions.assertThat;
import java.nio.charset.StandardCharsets;
import java.util.Base64;
import org.junit.Test;
public class MIMEEncodingDecodingTest {
@Test
public void encode() throws Exception {
Base64.Encoder encoder = Base64.getMimeEncoder();
StringBuilder value = new StringBuilder();
value.append("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
System.out.println(value);
byte[] result = encoder.encode(value.toString().getBytes(StandardCharsets.UTF_8.toString()));
System.out.println(result);
System.out.println(new String(result));
assertThat(new String(result)).containsIgnoringNewLines(
"SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0\n" + "NjAsIElUIDQ4NA==");
}
@Test
public void decode() throws Exception {
Base64.Decoder decoder = Base64.getMimeDecoder();
String value = "SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0\n"
+ "NjAsIElUIDQ4NA==";
System.out.println(value);
byte[] result = decoder.decode(value.toString().getBytes(StandardCharsets.UTF_8.toString()));
System.out.println(result);
System.out.println(new String(result));
assertThat(new String(result)).isEqualTo("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
}
@Test
public void Base64_encodeBase64Chunked() throws Exception {
StringBuilder value = new StringBuilder();
value.append("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
System.out.println(value);
byte[] result = org.apache.commons.codec.binary.Base64
.encodeBase64Chunked(value.toString().getBytes(StandardCharsets.UTF_8.toString()));
System.out.println(result);
System.out.println(new String(result));
assertThat(new String(result)).containsIgnoringNewLines(
"SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0\n" + "NjAsIElUIDQ4NA==");
}
@Test
public void Base64_decodeBase64() throws Exception {
String value = "SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0\n"
+ "NjAsIElUIDQ4NA==";
System.out.println(value);
byte[] result = org.apache.commons.codec.binary.Base64
.decodeBase64(value.getBytes(StandardCharsets.UTF_8.toString()));
System.out.println(result);
System.out.println(new String(result));
assertThat(new String(result)).isEqualTo("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
}
@Test
public void Base64_decodeBase64WithString() throws Exception {
String value = "SmF2YSAxNDcsIFNwcmluZyBib290IDE2OCwgSnVuaXQgMTUxLCBBc3NlcnRKIDE1NSwgQmFzaCA0\n"
+ "NjAsIElUIDQ4NA==";
System.out.println(value);
byte[] result = org.apache.commons.codec.binary.Base64.decodeBase64(value);
System.out.println(result);
System.out.println(new String(result));
assertThat(new String(result)).isEqualTo("Java 147, Spring boot 168, Junit 151, AssertJ 155, Bash 460, IT 484");
}
}心得分享
Java MIME Encoding Decoding 依照 RFC 2045 中指定的 Base64 字母表，輸出映射到一組字元A-Za-z0-9+/ ，將忽略所有在 Base64 字母表中，找不到的行分隔符號或其他字元，熟悉 MIME Encoder Decoder in Java 工具類別提供的靜態方法，取得 MIME 編碼器，進行編碼解碼的操作。
