英文:
Convert a bit to Base64 character
问题
我需要将一个二进制字符串（"110100"，十进制为52）转换为对应的Base64字符，我知道对应的字符是"0"。在Java中有没有这样的方法？我阅读了多个Base64指南，但是我找不到答案。
为了澄清起见，转换表在这里：https://www.lifewire.com/base64-encoding-overview-1166412（Base64编码表部分）。我想要在已知52的情况下，将其转换为"0"字符。
非常感谢。
英文:
I need to convert a binary String ("110100", 52 in decimal) to its corresponding Base64 character, that I know is "0". Is any way in Java to do that? I was reading multiple base 64 guides but I cant reach the answer.
For clarification, the conversion table is here: https://www.lifewire.com/base64-encoding-overview-1166412 (Base64 Encoding Table section) I want having the 52, convert it to "0" char.
Thanks a lot.
答案1
得分: 1
由于一个字节长度为8位，而Base64通过仅使用6位来构造其值，我能想到的最简单的方法是在所需字符开头附加两个字符，然后仅取结果的最后一个字符：
String encode = String.format("00%s", (char) Integer.parseInt("110100", 2));
String encoded = new String(Base64.getEncoder().encode(encode.getBytes()));
System.out.println(encoded.charAt(encoded.length() - 1));
// 输出：0
英文:
Since a byte is 8 bits long and Base64 makes up its values by grabbing only 6 bits the simplest way I can think of is appending two characters at the beginning of your desired character and taking only the last character of the result:
String encode = String.format("00%s", (char) Integer.parseInt("110100", 2));
String encoded = new String(Base64.getEncoder().encode(encode.getBytes()));
System.out.println(encoded.charAt(encoded.length() - 1));
// Prints: 0
答案2
得分: 0
你首先需要将二进制字符串转换为字节数组。有很多关于如何完成这个操作的帖子，但在伪代码中，它看起来像是这样的。
读取最多4个字符；
Byte.parseByte(chars, 2);
添加到字节数组；
然后你可以使用 Base64.Encoder 来对字节进行编码。
英文:
You first need to convert your binary string into a byte array. There are a number of posts on how to accomplish this but in pseudo code it would look like the following.
Read up to 4 characters;
Byte.parseByte(chars, 2);
Append to byte array;
Then you can use Base64.Encoder to encode the bytes.
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