JavaScript Base64 encoding and decoding to implement URL parameter passing.

JavaScript Base64 encoding and decoding to implement URL parameter passing. _javascript skills

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Release： 2016-05-16 19:26:15

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为什么需要对参数进行编码？相信有过开发的经验的广大程序员都知道，在Web中，若是直接在Url地址上传递参数值，若是中文，或者+等什么的就会出现乱码现象，若是数字或者英文的好象没有什么问题，简言之，传递过来的参数是需要进行编码的。
在这里，也许有人会说，为什么不直接用Server.UrlDecode和Server.UrlEncode这两个来进行编码和解码的操作呢？

的确，这两个服务器端对象很好使用，用起来也很方便，但是，若在客户端是HTML的Input，查询的时候页面是HTML或者其他的，反正不是.NET的，那这个对象还可以用吗？

我现在就遇到这样的问题，查询的东东放在页面，而且那个页面我根本不想让他是.aspx结尾的，哈，感觉HTML的挺不错，而且里面的控件也是用HTML对象的。

下面先来看两个函数，UTF16转UTF8和UTF8转Utf16的。
function utf16to8(str) {
var out, i, len, c;

    out = "";
    len = str.length;
    for(i = 0; i < len; i++) {
c = str.charCodeAt(i);
if ((c >= 0x0001) && (c <= 0x007F)) {
out += str.charAt(i);
} else if (c > 0x07FF) {
     out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
     out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F));
     out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
} else {
     out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F));
     out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
}
    }
    return out;
}

function utf8to16(str) {
var out, i, len, c;
var char2, char3;

    out = "";
    len = str.length;
    i = 0;
    while(i < len) {
c = str.charCodeAt(i++);
switch(c >> 4)
{
   case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
     // 0xxxxxxx
     out += str.charAt(i-1);
     break;
   case 12: case 13:
     // 110x xxxx   10xx xxxx
     char2 = str.charCodeAt(i++);
     out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
break;
case 14:
// 1110 xxxx 10xx xxxx 10xx xxxx
char2 = str.charCodeAt(i++);
char3 = str.charCodeAt(i++);
out += String.fromCharCode(((c & 0x0F) << 12) |
((char2 & 0x3F) << 6) |
((char3 & 0x3F) << 0));
break;
}
}

return out;
}

那么为什么需要进行转化呢？因为在JavaScript中获得的中文字符是用UTF16进行编码的，和我们统一的页面标准格式UTF-8可不一样哦，所以需要先进行转化，上面的函数UTF-16到UTF8，然后再进行Base64的编码。

下面是关于Js进行Base64编码和解码的相关操作：

var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var base64DecodeChars = new Array(
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1);
//客户端Base64编码
function base64encode(str) {
var out, i, len;
var c1, c2, c3;

len = str.length;
i = 0;
out = "";
while(i < len) {
c1 = str.charCodeAt(i++) & 0xff;
if(i == len)
{
out += base64EncodeChars.charAt(c1 >> 2);
     out += base64EncodeChars.charAt((c1 & 0x3) << 4);
out += "==";
break;
}
c2 = str.charCodeAt(i++);
if(i == len)
{
out += base64EncodeChars.charAt(c1 >> 2);
     out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));
     out += base64EncodeChars.charAt((c2 & 0xF) << 2);
out += "=";
break;
}
c3 = str.charCodeAt(i++);
out += base64EncodeChars.charAt(c1 >> 2);
out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));
out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >>6));
out += base64EncodeChars.charAt(c3 & 0x3F);
    }
    return out;
}
//客户端Base64解码
function base64decode(str) {
    var c1, c2, c3, c4;
    var i, len, out;

    len = str.length;
    i = 0;
    out = "";
    while(i < len) {
/* c1 */
do {
c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
} while(i < len && c1 == -1);
if(c1 == -1)
break;

/* c2 */
do {
c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
} while(i < len && c2 == -1);
if(c2 == -1)
break;

out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));

/* c3 */
do {
     c3 = str.charCodeAt(i++) & 0xff;
     if(c3 == 61)
return out;
     c3 = base64DecodeChars[c3];
} while(i < len && c3 == -1);
if(c3 == -1)
break;

out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));

/* c4 */
do {
     c4 = str.charCodeAt(i++) & 0xff;
     if(c4 == 61)
return out;
     c4 = base64DecodeChars[c4];
} while(i < len && c4 == -1);
if(c4 == -1)
break;
out += String.fromCharCode(((c3 & 0x03) << 6) | c4);
}
return out;
}

这样传递过去的值就可以在服务器端解码操作了。
下面是C#的Base64加码和解码的相关类：
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

namespace CNVP.Base64
{
///

/// Summary description of MyBase64
///

public class MyBase64
{
public MyBase64()
{
//
// TODO: Add constructor logic here
//
}
///

                                                                                                                     Server-side Base64 encoding                                                                                                             byte[] encData_byte = new byte[data.Length ];
encData_byte = System.Text.Encoding.UTF8.GetBytes(data);
string encodedData = Convert.ToBase64String(encData_byte);
return encodedData;
         }
              catch (Exception e ; >          /// Server-side Base64 decoding
///

///
///
public string base64Decode (string data) System.Text.Decoder utf8Decode = encoder. GetDecoder();
byte[] todecode_byte = Convert.FromBase64String(data); char[] decoded_char = new char[charCount ];
utf8Decode.GetChars(todecode_byte, 0, todecode_byte.Length, decoded_char, 0);
string result = new String(decoded_char);
return result;
         }
                  catch (Exception e)
                                                                                                                                                                                                                                                          throw new Exception(" "       e.Message);

var Keyword=base64encode(utf16to8(document.all.Keyword.value));
Keyword=Keyword.replace(" ","+" );//Replacement, otherwise an error will occur when the server decodes
The server side uses the following code call:
                                  .MyBase64(); Keyword=base64.base64Decode(Keyword);