在开发Java Web应用的时候,可能会在服务器端用Java做Base64编码,而在客户端用JavaScript进行解码。这样就要求两边的Base64编码机制保持一致。
使 用Base64编码,可能会碰到各种奇怪情况,甚至怀疑编码有bug。但实际上不是这样的。Base64理论上操作的对象不是字符串而是字节数组。它的原 理就是把ASCII码的255个字符缩小到用64个来表示。具体就是原来三个字节用四个字节表示,编码后长度有一定的增长。
1) 最好一次编码,避免分段编码,确实要分段编码,每一段字节数应该是3的倍数。
长字节流,如果要边读取边编码,每一段必须是3的倍数,否则就可能在还原的时候出乱。一般人喜欢用2的乘方来定义数组,例如 byte[1024],因为不是3的倍数,可能还原时出错。正确的例子是:
byte[] bs=new byte[3*100] ....inputStream.read(bs)......encode(bs )....
对于字符串,一般要整个一次编码,以避免分段编码出错。
当然,如果你分段编码,还原的时候也是一段一段地还原,那是没有问题的。
2)确保字符串还原的时候按照原来的编码还原。
因为它操作的是字节数组,所以对于GBK编码的汉字和UTF-8编码汉字,经过 Base64编码后结果是不一样的。例如“我们”这两个字如果是GBK编码,转成Base64后就是ztLDxw== ;如果是UTF-8编码,转成Base64后就是5oiR5Lus。
也就是 “我们” ==》 getBytes("GBK") ==> Base64
所以Java这边用什么编码转换,在JavaScript那边就要用什么编码还原。要保证Java和JavaScript通用,我们采用Unicode的编码(JavaScript转成UTF-8、GBK不方便,所以就采用了其本身的Unicode编码),具体如下:
服务器端:
1)用getBytes("Unicode")转成Unicode字节数组。
2) 编码成Base64字符串
3)传送到客户端
客户端:
1)Base64 解码成字节数组
2)按Unicode还原
代码如下(相关的函数看附件):
Base64.encode(data,"Unicode"); //java 端编码
decode64(data); //javascript解码
附一:Java中Base64编码
package websharp.util; public class Base64 { private static final byte[] encodingTable = { (byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F', (byte) 'G', (byte) 'H', (byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N', (byte) 'O', (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', (byte) 'U', (byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z', (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f', (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n', (byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r', (byte) 's', (byte) 't', (byte) 'u', (byte) 'v', (byte) 'w', (byte) 'x', (byte) 'y', (byte) 'z', (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', (byte) '6', (byte) '7', (byte) '8', (byte) '9', (byte) '+', (byte) '/' }; private static final byte[] decodingTable; static { decodingTable = new byte[128]; for (int i = 0; i < 128; i++) { decodingTable[i] = (byte) -1; } for (int i = 'A'; i <= 'Z'; i++) { decodingTable[i] = (byte) (i - 'A'); } for (int i = 'a'; i <= 'z'; i++) { decodingTable[i] = (byte) (i - 'a' + 26); } for (int i = '0'; i <= '9'; i++) { decodingTable[i] = (byte) (i - '0' + 52); } decodingTable['+'] = 62; decodingTable['/'] = 63; } public static byte[] encode(byte[] data,int offset) { byte[] bytes; int realCount=data.length-offset; int modulus = realCount % 3; if (modulus == 0) { bytes = new byte[(4 * realCount) / 3]; } else { bytes = new byte[4 * ((realCount / 3) + 1)]; } int dataLength = (data.length - modulus); int a1; int a2; int a3; for (int i = offset, j = 0; i < dataLength; i += 3, j += 4) { a1 = data[i] & 0xff; a2 = data[i + 1] & 0xff; a3 = data[i + 2] & 0xff; bytes[j] = encodingTable[(a1 >>> 2) & 0x3f]; bytes[j + 1] = encodingTable[((a1 << 4) | (a2 >>> 4)) & 0x3f]; bytes[j + 2] = encodingTable[((a2 << 2) | (a3 >>> 6)) & 0x3f]; bytes[j + 3] = encodingTable[a3 & 0x3f]; } int b1; int b2; int b3; int d1; int d2; switch (modulus) { case 0: /* nothing left to do */ break; case 1: d1 = data[data.length - 1] & 0xff; b1 = (d1 >>> 2) & 0x3f; b2 = (d1 << 4) & 0x3f; bytes[bytes.length - 4] = encodingTable[b1]; bytes[bytes.length - 3] = encodingTable[b2]; bytes[bytes.length - 2] = (byte) '='; bytes[bytes.length - 1] = (byte) '='; break; case 2: d1 = data[data.length - 2] & 0xff; d2 = data[data.length - 1] & 0xff; b1 = (d1 >>> 2) & 0x3f; b2 = ((d1 << 4) | (d2 >>> 4)) & 0x3f; b3 = (d2 << 2) & 0x3f; bytes[bytes.length - 4] = encodingTable[b1]; bytes[bytes.length - 3] = encodingTable[b2]; bytes[bytes.length - 2] = encodingTable[b3]; bytes[bytes.length - 1] = (byte) '='; break; } return bytes; } public static byte[] decode(byte[] data) { byte[] bytes; byte b1; byte b2; byte b3; byte b4; data = discardNonBase64Bytes(data); if (data[data.length - 2] == '=') { bytes = new byte[(((data.length / 4) - 1) * 3) + 1]; } else if (data[data.length - 1] == '=') { bytes = new byte[(((data.length / 4) - 1) * 3) + 2]; } else { bytes = new byte[((data.length / 4) * 3)]; } for (int i = 0, j = 0; i < (data.length - 4); i += 4, j += 3) { b1 = decodingTable[data[i]]; b2 = decodingTable[data[i + 1]]; b3 = decodingTable[data[i + 2]]; b4 = decodingTable[data[i + 3]]; bytes[j] = (byte) ((b1 << 2) | (b2 >> 4)); bytes[j + 1] = (byte) ((b2 << 4) | (b3 >> 2)); bytes[j + 2] = (byte) ((b3 << 6) | b4); } if (data[data.length - 2] == '=') { b1 = decodingTable[data[data.length - 4]]; b2 = decodingTable[data[data.length - 3]]; bytes[bytes.length - 1] = (byte) ((b1 << 2) | (b2 >> 4)); } else if (data[data.length - 1] == '=') { b1 = decodingTable[data[data.length - 4]]; b2 = decodingTable[data[data.length - 3]]; b3 = decodingTable[data[data.length - 2]]; bytes[bytes.length - 2] = (byte) ((b1 << 2) | (b2 >> 4)); bytes[bytes.length - 1] = (byte) ((b2 << 4) | (b3 >> 2)); } else { b1 = decodingTable[data[data.length - 4]]; b2 = decodingTable[data[data.length - 3]]; b3 = decodingTable[data[data.length - 2]]; b4 = decodingTable[data[data.length - 1]]; bytes[bytes.length - 3] = (byte) ((b1 << 2) | (b2 >> 4)); bytes[bytes.length - 2] = (byte) ((b2 << 4) | (b3 >> 2)); bytes[bytes.length - 1] = (byte) ((b3 << 6) | b4); } return bytes; } public static byte[] decode(String data) { byte[] bytes; byte b1; byte b2; byte b3; byte b4; data = discardNonBase64Chars(data); if (data.charAt(data.length() - 2) == '=') { bytes = new byte[(((data.length() / 4) - 1) * 3) + 1]; } else if (data.charAt(data.length() - 1) == '=') { bytes = new byte[(((data.length() / 4) - 1) * 3) + 2]; } else { bytes = new byte[((data.length() / 4) * 3)]; } for (int i = 0, j = 0; i < (data.length() - 4); i += 4, j += 3) { b1 = decodingTable[data.charAt(i)]; b2 = decodingTable[data.charAt(i + 1)]; b3 = decodingTable[data.charAt(i + 2)]; b4 = decodingTable[data.charAt(i + 3)]; bytes[j] = (byte) ((b1 << 2) | (b2 >> 4)); bytes[j + 1] = (byte) ((b2 << 4) | (b3 >> 2)); bytes[j + 2] = (byte) ((b3 << 6) | b4); } if (data.charAt(data.length() - 2) == '=') { b1 = decodingTable[data.charAt(data.length() - 4)]; b2 = decodingTable[data.charAt(data.length() - 3)]; bytes[bytes.length - 1] = (byte) ((b1 << 2) | (b2 >> 4)); } else if (data.charAt(data.length() - 1) == '=') { b1 = decodingTable[data.charAt(data.length() - 4)]; b2 = decodingTable[data.charAt(data.length() - 3)]; b3 = decodingTable[data.charAt(data.length() - 2)]; bytes[bytes.length - 2] = (byte) ((b1 << 2) | (b2 >> 4)); bytes[bytes.length - 1] = (byte) ((b2 << 4) | (b3 >> 2)); } else { b1 = decodingTable[data.charAt(data.length() - 4)]; b2 = decodingTable[data.charAt(data.length() - 3)]; b3 = decodingTable[data.charAt(data.length() - 2)]; b4 = decodingTable[data.charAt(data.length() - 1)]; bytes[bytes.length - 3] = (byte) ((b1 << 2) | (b2 >> 4)); bytes[bytes.length - 2] = (byte) ((b2 << 4) | (b3 >> 2)); bytes[bytes.length - 1] = (byte) ((b3 << 6) | b4); } for(int i=0;i<bytes.length;i++) System.out.println(","+bytes[i]); return bytes; } private static byte[] discardNonBase64Bytes(byte[] data) { byte[] temp = new byte[data.length]; int bytesCopied = 0; for (int i = 0; i < data.length; i++) { if (isValidBase64Byte(data[i])) { temp[bytesCopied++] = data[i]; } } byte[] newData = new byte[bytesCopied]; System.arraycopy(temp, 0, newData, 0, bytesCopied); return newData; } private static String discardNonBase64Chars(String data) { StringBuffer sb = new StringBuffer(); int length = data.length(); for (int i = 0; i < length; i++) { if (isValidBase64Byte((byte) (data.charAt(i)))) { sb.append(data.charAt(i)); } } return sb.toString(); } private static boolean isValidBase64Byte(byte b) { if (b == '=') { return true; } else if ((b < 0) || (b >= 128)) { return false; } else if (decodingTable[b] == -1) { return false; } return true; } public static String encode(String data,String charset)throws Exception { // byte[] result = (data.getBytes("Unicode")); if(data==null || data.length()==0) return data; int offset=0; // getBytes("unicode")转完后会在前头加上两字节”FE“ byte[] result=encode (data.getBytes(charset),offset); StringBuffer sb=new StringBuffer(result.length); for (int i=0;i<result.length;i++) sb.append((char)result[i]); return sb.toString(); } public static String decode(String data,String charset)throws Exception { if(data==null || data.length()==0) return data; return new String(Base64.decode(data),charset); } public static void main(String[] args) throws Exception { String data = "我们"; String data1=encode(data,"Unicode"); String data2=decode(data1,"Unicode"); System.out.println(data); System.out.println(data1); System.out.println(data2); } }
|
附二:JavaScript中Base64编码
<html>
<head>
<title>base64 Encoding/Decoding</title>
</head>
<script type="text/javascript"><!--
var keyStr = "ABCDEFGHIJKLMNOP" +
"QRSTUVWXYZabcdef" +
"ghijklmnopqrstuv" +
"wxyz0123456789+/" +
"=";
function encode64(input) {
input = unicodetoBytes(input);
var output = "";
var chr1, chr2, chr3 = "";
var enc1, enc2, enc3, enc4 = "";
var i = 0;
do {
chr1 = input[i++];
chr2 = input[i++];
chr3 = input[i++];
enc1 = chr1 >> 2;
enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
enc4 = chr3 & 63;
if (isNaN(chr2)) {
enc3 = enc4 = 64;
} else if (isNaN(chr3)) {
enc4 = 64;
}
output = output +
keyStr.charAt(enc1) +
keyStr.charAt(enc2) +
keyStr.charAt(enc3) +
keyStr.charAt(enc4);
chr1 = chr2 = chr3 = "";
enc1 = enc2 = enc3 = enc4 = "";
} while (i < input.length);
return output;
}
function decode64(input) {
var output = "";
var chr1, chr2, chr3 = "";
var enc1, enc2, enc3, enc4 = "";
var i = 0;
// remove all characters that are not A-Z, a-z, 0-9, +, /, or =
var base64test = /[^A-Za-z0-9/+///=]/g;
if (base64test.exec(input)) {
alert("There were invalid base64 characters in the input text./n" +
"Valid base64 characters are A-Z, a-z, 0-9, '+', '/', and '='/n" +
"Expect errors in decoding.");
}
input = input.replace(/[^A-Za-z0-9/+///=]/g, "");
output=new Array();
do {
enc1 = keyStr.indexOf(input.charAt(i++));
enc2 = keyStr.indexOf(input.charAt(i++));
enc3 = keyStr.indexOf(input.charAt(i++));
enc4 = keyStr.indexOf(input.charAt(i++));
chr1 = (enc1 << 2) | (enc2 >> 4);
chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
chr3 = ((enc3 & 3) << 6) | enc4;
output.push(chr1);
if (enc3 != 64) {
output.push(chr2);
}
if (enc4 != 64) {
output.push(chr3);
}
chr1 = chr2 = chr3 = "";
enc1 = enc2 = enc3 = enc4 = "";
} while (i < input.length);
return bytesToUnicode(output);
}
function unicodetoBytes(s)
{
var result=new Array();
if(s==null || s=="") return result;
result.push(255); // add "FE" to head
result.push(254);
for(var i=0;i<s.length;i++)
{
var c=s.charCodeAt(i).toString(16);
if(c.length==1) i="000"+c;
else if(c.length==2) c="00"+c;
else if(c.length==3) c="0"+c;
var var1=parseInt( c.substring(2),16);
var var2=parseInt( c.substring(0,2),16);
result.push( var1);
result.push(var2) ;
}
return result;
}
function bytesToUnicode(bs)
{
var result="";
var offset=0;
if(bs.length>=2 && bs[0]==255 && bs[1]==254) offset=2; // delete "FE"
for(var i=offset;i<bs.length;i+=2)
{
var code=bs[i]+(bs[i+1]<<8);
result+=String.fromCharCode(code);
}
return result;
}
//-->
</script>
<body>
<form name="base64Form">
Type in the message you want to encode in base64, or paste<br>
base64 encoded text into the text field, select Encode or Decode, <br>
and click the button!<br>
<textarea name="theText" cols="40" rows="6"></textarea><br>
<input type="button" name="encode" value="Encode to base64"
onClick="document.base64Form.theText.value=encode64(document.base64Form.theText.value);">
<input type="button" name="decode" value="Decode from base64"
onClick="document.base64Form.theText.value=decode64(document.base64Form.theText.value);">
</form>
</body>
</html>
相关推荐
主要介绍了Java 和 JavaScript 真正通用的Base64编码详解的相关资料,附有Java和Javascript 的Base64编码,需要的朋友可以参考下
Delphi进行Base64编码后,如果使用javascript解码,会出现如下问题: 1. 汉字乱码 2. 空格变成 + 号 本资源演示Delphi代码,实现javascript能正确进行Base64解码,不出现上述2个问题。 解决思路:进行Base64前先...
java端:返回类型非字符接口调用StringUtils#base64AndCompressJson进行编码压缩 ,返回类型为字符接口调用StringUtils#base64Andcompress js 端:引入压缩包中的js文件 ,调用deBase64AndUncompress进行解压解码
提供一种Base64编码,并输出UTF-8格式的BASE64编码方式。本程序在微信小程序开发工具中已经测试通过。 Base64代码: [javascript] view plain copy print? (function(){ var BASE64_MAPPING = [ 'A','B','C','D',...
由于遇到做一个支付平台的接口参数要做base64 于是就写了一个用javascript编写的方法,对方支付平台是java的 ,于就将中文做了一个unicode转为assi码处理。
3des加密解密 base64编码解码的源代码 完全与标准算法一致,与C# java 结果一致
在Base64中的可打印字符包括字母A-Z、a-z、数字0-9,这样共有62个字符,此外的两个可打印符号在不同的系统中而不同,一般为+和/。 转换原理 Base64的直接数据源是二进制序列(Binary Sequence)。当然,你也可以将图片...
本文实例讲述了jQuery实现文件编码成base64并通过AJAX上传的方法。...灵光一闪,利用javascript的FileReader对象将文件编码成base64再传服务器不就行了么~ 开始动手,丰衣足食。 前端对文件进行base64编码并通过aj
Javascript Base64编码解码
最近发现记忆力越来越差,所以需要记录下代码,能拿起来就用的那种。当前项目工程支持javascript和java之间相互转换,使用了url-safe(url安全)的模式。
javascript版本的 base64解码和编码函数。
javascript 下,将字符串按gbk方式编码的Base64加解码。js gbk的base64
用javascript实现的base64编码与解码器
用JavaScript实现PHP里的Base64编码与解码。 使用方法: encode64('要编码的字符串'); decode64('要解码的字符串');
base64.js 是 Base64 的 JavaScript 实现。浏览器:[removed][removed]node.jsvar Base64 = require('./base64.js').Base64;示例:Base64.encode('dankogai'); // ZGFua29nYWk= Base64.encode('小飼弾'); // ...
前端实现Base64对文本和图片的编码,后端用Java Servlet作为接口实现编码的解码.
获取图片的base64编码,和通过base64编码下载图片
JavaScript-base64的源码,可对明文密码进行加密解密; //1.加密 var str = '密码'; var base = new Base64(); var result = base.encode(str); //document.(result); //2.解密 var result2 = base.decode...
虽然JavaScript中可以使用原生的btoa和atob函数进行Base64的编解码。但是不支持中文字符,并且不支持url-safe的Base64编解码。当编码后的结果要是通过get请求传输时(比如跨域提交时),结果中包含有'/'字符将导致...