タイプフィールドの入力をバイナリーではなく、ベース64でデータを送信します。

Question

html4に簡単なアップロードフォームを書いています。通常、これは非常に単純なプロセスです。私が実行している問題は、画像データのためのものです。サーバーはbase64を期待していて、base64として送信するものは何も処理しないため、画像が壊れてしまいます。フォームに設定できる属性がありますか？もしそうでなければ、サーバーに送る前にbase64にデータをエンコードするためのjavascriptを設定できますか？

Answer 1

ここにはよく文書化されたbase64エンコーダ/デコーダhttp://hellerim.net/base64_src.phpへのリンクがあります。私はこのコードを修正しました（下記参照）ので、 "コア"クラスは必要ありませんでした。

/// BEGIN_DOC(base64).METHOD(decode) 
/// 
// method RETURNTYPE base64.decode(String inp [, enum outType [, bool safe [, bool lax]]]) 
// 
// Encode input data into a base64 character string. 
// 
// Function arguments: 
//  String inp:   base64 encoded data string to be decoded. 
//  enum outType   Optional. This parameter specifies the type of the output and determines 
//       how the input data is to be interpreted.: 
//        0 - binary data; create a byte array (default) 
//        1 - 8-bit character string, assuming 1-byte characters encoded in inp 
//        2 - 16-bit (UniCode) character string, assuming 2-byte 
//         characters encoded in inp 
//       If 2 is passed to the function, but the number of base64 characters 
//       is odd, a value of null is returned. 
//  bool safe    Optional. If this parameter is set to true, the standard base64 
//       character set is replaced with a modified version where 
//       the characters '+' and '/' are replaced with '-' and '_', 
//       repectively, in order to avoid problems with file system 
//       namings which otherwise could occur on some systems. 
//       By default, the value of this argument is assumed to be 
//       false. 
//  bool lax    Optional. If set to true, the function skips all input characters which 
//       cannot be processed. This includes the character '=', too, if 
//       it is followed by at least one different character before the string 
//       ends. However, if skipping infeasible characters amounts to a number 
//       of allowed base64 characters which is not amultiple of 4, 
//       this is considered an error and null is returned. 
//       If lax is set to false (the default), null is returned 
//       whenever an infeasible character is found. 
//       The purpose of this parameter is to give support in cases 
//       where data has been base64 encoded and later on was folded by 
//       some other software, e.g. '\r\n\'s have been inserted in email. 
//       exchange. 
// Return value:    The function's processing result value is stored in a string or in 
//       a byte array before it is returned, depending on the value 
//       assigned to the type parameter. In each case, the value 
//       maybe empty but not null if no error occurred. 
// Errors:     Whenever an error occurs, null is returned. Parameter values 
//       not defined above are considered errors. 
// 
/// END_DOC 

base64.decode = function(inp, outType, safe, lax) { 

    // do some argument checking 
    if (arguments.length < 1) return null; 
    if (arguments.length < 2) outType = 0; // produce character array by default 
    if (outType != 0 && outType != 1 && outType != 2) return null; 
    if (arguments.length >= 3 && safe != true && safe != false) return null; 
    var sEnc = (arguments.length >= 3 && safe) ? this.encStringS : this.encString; // select encoding character set 
    if (arguments.length >= 4 && lax != true && lax != false) return null; 
    var aDec = {};    // create an associative array for decoding 
    for (var p = 0; p < sEnc.length; p++) { // populate array 
    aDec[sEnc.charAt(p)] = p; 
    } 
    var out = (outType == 0) ? [] : ''; 
    lax = (arguments.length == 4 && lax); // ignore non-base64 characters 
    var l = 0;    // work area 
    var i = 0;    // index into input 
    var j = 0;    // sextett counter 
    var c = 0;    // input buffer 
    var k = 0;    // index into work area 
    var end = inp.length; // one position past the last character to be processed 
    var C = ''; 
    // check input 
    if (lax) { 
    var inpS = '';   // shadow input 
    var ignore = false; // determines wether '=' must be counted 
    var cnt = 0; 
    for (var p = 1; p <= inp.length; p++) { // check and cleanup string before trying to decode 
     c = inp.charAt(end - p); 
     if (c == '=') { 
     if (!ignore) { 
      if (++cnt > 1) ignore = true; 
     } else { 
      continue; 
     } 
     } else if (undefined != aDec[c]) { // the character is base64, hence feasible 
     if (!ignore) ignore = true;  // no more '=' allowed 
     inpS = c + inpS;     // prepend c to shadow input 
     } 
    } 
    for (var p = 0; p <= cnt; p++) {  // at most cnt '=''s were garbage, a number in 
     if (p == 2) return null;   // [inpS.length, inpS.length + cnt] must be a 
     if ((inpS.length + cnt) % 4 == 0) break; // multiple of 4 
    } 
    if (inpS.length % 4 == 1) return null; // must be 0, 2, or 3 for inpS to contain correctly base64 encoded data 
    inp = inpS;       // inp now contains feasible characters only 
    end = inp.length; 
    } else { 
    if (inp.length % 4 > 0) return null; // invalid length 
    for (var p = 0; p < 2; p++) {  // search for trailing '=''s 
     if (inp.charAt(end - 1) == '=') { 
     end--; 
     } else { 
     break; 
     } 
    } 
    } 
    // convert 
    for (i = 0; i < end; i++) { 
    l <<= 6;        // clear space for next sextett 
    if (undefined == (c = aDec[inp.charAt(i)])) return null; // lax must be false at this place! 
    l |= (c & 0x3f); // append it 
    if (j == 0) { 
     j++; 
     continue;       // work area contains incomplete byte only 
    } 
    if (outType == 2) { 
     if (k == 1) {      // work area contains complete double byte 
     out += String.fromCharCode(l >> (2 * (3 - j))); // convert leftmost 16 bits and append them to string 
     l &= ~(0xffff << (2 * (3 - j)));  // clear the 16 processed bits 
     } 
     k = ++k % 2; 
    } else {        // work area contains complete byte 
     if (outType == 0) { 
     out.push(l >> (2 * (3 - j)));   // append byte to array 
     } else { 
     out += String.fromCharCode(l >> (2 * (3 - j))); // convert leftmost 8 bits and append them to String 
     } 
     l &= ~(0xff << (2 * (3 - j)));   // clear the 8 processed bits 
    } 
    j = ++j % 4;       // increment sextett counter cyclically 
    } 
    if (outType == 2 && k == 1) return null; // incomplete double byte in work area 

    return out; 
}