在Java 7中，我编写了这个方法

import javax.xml.bind.DatatypeConverter;

public static String toBase64(String data) {
    return DatatypeConverter.printBase64Binary(data.getBytes());
}

在Java 8中，它可以这样做: Base64.getEncoder () .encodeToString (string.getBytes (StandardCharsets.UTF_8))

下面是一个简短、完整的例子:

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

public class Temp {
    public static void main(String... args) throws Exception {
        final String s = "old crow medicine show";
        final byte[] authBytes = s.getBytes(StandardCharsets.UTF_8);
        final String encoded = Base64.getEncoder().encodeToString(authBytes);
        System.out.println(s + " => " + encoded);
    }
}

输出:

old crow medicine show => b2xkIGNyb3cgbWVkaWNpbmUgc2hvdw==

我尝试使用以下代码片段。它运行得很好。: -)

com.sun.org.apache.xml.internal.security.utils.Base64.encode("The string to encode goes here");

GZIP + Base64

Base64格式的字符串长度比原始长度大:平均133%。因此，首先用GZIP压缩它，然后编码到Base64是有意义的。对于超过200个字符的字符串，它最多可以减少77%。例子:

public static void main(String[] args) throws IOException {
    byte[] original = randomString(100).getBytes(StandardCharsets.UTF_8);

    byte[] base64 = encodeToBase64(original);
    byte[] gzipToBase64 = encodeToBase64(encodeToGZIP(original));

    byte[] fromBase64 = decodeFromBase64(base64);
    byte[] fromBase64Gzip = decodeFromGZIP(decodeFromBase64(gzipToBase64));

    // test
    System.out.println("Original: " + original.length + " bytes, 100%");
    System.out.println("Base64: " + base64.length + " bytes, "
            + (base64.length * 100 / original.length) + "%");
    System.out.println("GZIP+Base64: " + gzipToBase64.length + " bytes, "
            + (gzipToBase64.length * 100 / original.length) + "%");

    //Original: 3700 bytes, 100%
    //Base64: 4936 bytes, 133%
    //GZIP+Base64: 2868 bytes, 77%

    System.out.println(Arrays.equals(original, fromBase64)); // true
    System.out.println(Arrays.equals(original, fromBase64Gzip)); // true
}

public static byte[] decodeFromBase64(byte[] arr) {
    return Base64.getDecoder().decode(arr);
}

public static byte[] encodeToBase64(byte[] arr) {
    return Base64.getEncoder().encode(arr);
}

public static byte[] decodeFromGZIP(byte[] arr) throws IOException {
    ByteArrayInputStream bais = new ByteArrayInputStream(arr);
    GZIPInputStream gzip = new GZIPInputStream(bais);
    return gzip.readAllBytes();
}

public static byte[] encodeToGZIP(byte[] arr) throws IOException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    GZIPOutputStream gzip = new GZIPOutputStream(baos);
    gzip.write(arr);
    gzip.finish();
    return baos.toByteArray();
}

public static String randomString(int count) {
    StringBuilder str = new StringBuilder();
    for (int i = 0; i < count; i++) {
        str.append(" ").append(UUID.randomUUID().toString());
    }
    return str.toString();
}

请参见:如何获取sun.misc的JAR文件。BASE64Encoder课吗?

Java 8包含它自己的Base64实现。然而，我发现了一个有点令人不安的区别。为了说明，我将提供一个代码示例:

我的编解码器包装:

public interface MyCodec
{
  static String apacheDecode(String encodedStr)
  {
    return new String(Base64.decodeBase64(encodedStr), Charset.forName("UTF-8"));
  }

  static String apacheEncode(String decodedStr)
  {
    byte[] decodedByteArr = decodedStr.getBytes(Charset.forName("UTF-8"));
    return Base64.encodeBase64String(decodedByteArr);
  }

  static String javaDecode(String encodedStr)
  {
    return new String(java.util.Base64.getDecoder().decode(encodedStr), Charset.forName("UTF-8"));
  }

  static String javaEncode(String decodedStr)
  {
    byte[] decodedByteArr = decodedStr.getBytes(Charset.forName("UTF-8"));
    return java.util.Base64.getEncoder().encodeToString(decodedByteArr);
  }
}

测试类:

public class CodecDemo
{
  public static void main(String[] args)
  {
    String decodedText = "Hello World!";

    String encodedApacheText = MyCodec.apacheEncode(decodedText);
    String encodedJavaText = MyCodec.javaEncode(decodedText);

    System.out.println("Apache encoded text: " + MyCodec.apacheEncode(encodedApacheText));
    System.out.println("Java encoded text: " + MyCodec.javaEncode(encodedJavaText));

    System.out.println("Encoded results equal: " + encodedApacheText.equals(encodedJavaText));

    System.out.println("Apache decode Java: " + MyCodec.apacheDecode(encodedJavaText));
    System.out.println("Java decode Java: " + MyCodec.javaDecode(encodedJavaText));

    System.out.println("Apache decode Apache: " + MyCodec.apacheDecode(encodedApacheText));
    System.out.println("Java decode Apache: " + MyCodec.javaDecode(encodedApacheText));
  }
}

输出:

Apache encoded text: U0dWc2JHOGdWMjl5YkdRaA0K

Java encoded text: U0dWc2JHOGdWMjl5YkdRaA==
Encoded results equal: false
Apache decode Java: Hello World!
Java decode Java: Hello World!
Apache decode Apache: Hello World!
Exception in thread "main" java.lang.IllegalArgumentException: Illegal base64 character d
    at java.util.Base64$Decoder.decode0(Base64.java:714)
    at java.util.Base64$Decoder.decode(Base64.java:526)
    at java.util.Base64$Decoder.decode(Base64.java:549)

注意，Apache编码文本在结尾包含额外的换行符(空格)。因此，为了让我的编解码器产生相同的结果，不管Base64实现如何，我必须在Apache编码的文本上调用trim()。在我的例子中，我简单地将前面提到的方法调用添加到我的编解码器的apacheDecode()，如下所示:

return Base64.encodeBase64String(decodedByteArr).trim();

一旦做出了这个改变，结果就像我所期望的那样:

Apache encoded text: U0dWc2JHOGdWMjl5YkdRaA==
Java encoded text: U0dWc2JHOGdWMjl5YkdRaA==
Encoded results equal: true
Apache decode Java: Hello World!
Java decode Java: Hello World!
Apache decode Apache: Hello World!
Java decode Apache: Hello World!

结论:如果你想从Apache Base64切换到Java，你必须:

用Apache解码器解码已编码的文本。 用Java编码产生的(纯)文本。

如果您没有按照这些步骤进行切换，很可能会遇到问题。这就是我的发现。

Apache Commons有一个很好的Base64实现。你可以简单地这样做:

// Encrypt data on your side using BASE64
byte[] bytesEncoded = Base64.encodeBase64(str .getBytes());
System.out.println("ecncoded value is " + new String(bytesEncoded));

// Decrypt data on other side, by processing encoded data
byte[] valueDecoded= Base64.decodeBase64(bytesEncoded );
System.out.println("Decoded value is " + new String(valueDecoded));

你可以在使用Java和JavaScript的base64编码中找到关于base64编码的更多细节。