Java一直缺少BASE64编码 API，以至于通常在项目开发中会选用第三方的API实现。但是，Java 8实现了BASE64编解码API，它包含到java.util包。下面我会对Java 8的BASE64 API做一个介绍。

java.util.Base64工具类提供了一套静态方法获取下面三种BASE64编解码器：

1）Basic编码
2）URL编码
3）MIME编码

Basic编码是标准的BASE64编码，用于处理常规的需求：输出的内容不添加换行符，而且输出的内容由字母加数字组成。下面是用法：

    // 编码        String asB64 = Base64.getEncoder().encodeToString("some string".getBytes("utf-8"));        System.out.println(asB64); // 输出为: c29tZSBzdHJpbmc=                 // 解码        byte[] asBytes = Base64.getDecoder().decode("c29tZSBzdHJpbmc=");        System.out.println(new String(asBytes, "utf-8")); // 输出为: some string  

URL编码也是我们经常会面对的需求，但由于URL对反斜线“/”有特殊的意义，因此URL编码需要替换掉它，使用下划线替换。比如下面的例子：

    String basicEncoded = Base64.getEncoder().encodeToString("subjects?abcd".getBytes("utf-8"));        System.out.println("Using Basic Alphabet: " + basicEncoded);                 String urlEncoded = Base64.getUrlEncoder().encodeToString("subjects?abcd".getBytes("utf-8"));        System.out.println("Using URL Alphabet: " + urlEncoded);        // 输出为:        Using Basic Alphabet: c3ViamVjdHM/YWJjZA==        Using URL Alphabet: c3ViamVjdHM_YWJjZA==  

MIME编码器会使用基本的字母数字产生BASE64输出，而且对MIME格式友好：每一行输出不超过76个字符，而且每行以“\r\n”符结束。比如下面的例子：

    StringBuilder sb = new StringBuilder();        for (int t = 0; t < 10; ++t) {          sb.append(UUID.randomUUID().toString());        }                byte[] toEncode = sb.toString().getBytes("utf-8");        String mimeEncoded = Base64.getMimeEncoder().encodeToString(toEncode);        System.out.println(mimeEncoded);        // 输出为:        NDU5ZTFkNDEtMDVlNy00MDFiLTk3YjgtMWRlMmRkMWEzMzc5YTJkZmEzY2YtM2Y2My00Y2Q4LTk5        ZmYtMTU1NzY0MWM5Zjk4ODA5ZjVjOGUtOGMxNi00ZmVjLTgyZjctNmVjYTU5MTAxZWUyNjQ1MjJj        NDMtYzA0MC00MjExLTk0NWMtYmFiZGRlNDk5OTZhMDMxZGE5ZTYtZWVhYS00OGFmLTlhMjgtMDM1        ZjAyY2QxNDUyOWZiMjI3NDctNmI3OC00YjgyLThiZGQtM2MyY2E3ZGNjYmIxOTQ1MDVkOGQtMzIz        Yi00MDg0LWE0ZmItYzkwMGEzNDUxZTIwOTllZTJiYjctMWI3MS00YmQzLTgyYjUtZGRmYmYxNDA4        Mjg3YTMxZjMxZmMtYTdmYy00YzMyLTkyNzktZTc2ZDc5ZWU4N2M5ZDU1NmQ4NWYtMDkwOC00YjIy        LWIwYWItMzJiYmZmM2M0OTBm  

public void wrapping() throws IOException {      String src = "This is the content of any resource read from somewhere" +        " into a stream. This can be text, image, video or any other stream.";          // 编码器封装OutputStream, 文件/tmp/buff-base64.txt的内容是BASE64编码的形式      try (OutputStream os = Base64.getEncoder().wrap(newFileOutputStream("/tmp/buff-base64.txt"))) {        os.write(src.getBytes("utf-8"));      }          // 解码器封装InputStream, 以及以流的方式解码, 无需缓冲      // is being consumed. There is no need to buffer the content of the file just for decoding it.      try (InputStream is = Base64.getDecoder().wrap(newFileInputStream("/tmp/buff-base64.txt"))) {        int len;        byte[] bytes = new byte[100];        while ((len = is.read(bytes)) != -1) {          System.out.print(new String(bytes, 0, len, "utf-8"));        }      }    }  

来自：http://blog.csdn.net/chszs