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==

与番石榴

pom.xml:

<dependency>
   <artifactId>guava</artifactId>
   <groupId>com.google.guava</groupId>
   <type>jar</type>
   <version>14.0.1</version>
</dependency>

示例代码:

// encode
String s = "Hello Việt Nam";
String base64 = BaseEncoding.base64().encode(s.getBytes("UTF-8"));

// decode
System.out.println("Base64:" + base64); // SGVsbG8gVmnhu4d0IE5hbQ==
byte[] bytes = BaseEncoding.base64().decode(base64);
System.out.println("Decoded: " + new String(bytes, "UTF-8")); // Hello Việt Nam

也可以使用Base64编码进行转换。为此，您可以使用javax.xml.bind。DatatypeConverter # printBase64Binary方法。

例如:

byte[] salt = new byte[] { 50, 111, 8, 53, 86, 35, -19, -47 };
System.out.println(DatatypeConverter.printBase64Binary(salt));

在Android上，使用Android .util的静态方法。Base64实用程序类。引用的文档说Base64类是在API级别8 (Android 2.2 (Froyo))中添加的。

import android.util.Base64;

byte[] encodedBytes = Base64.encode("Test".getBytes());
Log.d("tag", "encodedBytes " + new String(encodedBytes));

byte[] decodedBytes = Base64.decode(encodedBytes);
Log.d("tag", "decodedBytes " + new String(decodedBytes));

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。

使用Java 8中永不嫌晚的类:Java .util. base64

new String(Base64.getEncoder().encode(bytes));