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jQuery AJAX call messes up character encoding

由 与世无争的帅哥 提交于 2019-12-04 05:33:12

I finally figured it out. It's pretty weird!

response.setCharacterEncoding(String) does not work (don't know if it's related to my setup or what). It looks like it sets the character encoding, but for some reason jQuery messes it all up. You have the explicitly set the headers like so:

response.setHeader("Content-Type", "application/json; charset=ISO-8859-1");

Thanks for all the help, everyone!

EDIT

I did some research and checked out the JavaDocs and saw this:

Containers must communicate the character encoding used for the servlet response's writer to the client if the protocol provides a way for doing so. In the case of HTTP, the character encoding is communicated as part of the Content-Type header for text media types. Note that the character encoding cannot be communicated via HTTP headers if the servlet does not specify a content type; however, it is still used to encode text written via the servlet response's writer.

So the above still works, but you can also (and probably should) do this:

response.setContentType("application/json");
response.setCharacterEncoding("ISO-8859-1");

Can you use UTF-8, instead?

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

In PHP, you can encode JSON data as UTF-8:

/**
 * Applies a UTF-8 encoding conversion for text.
 */
function utf8_enc( $rows ) {
  $encoded = array();

  foreach( $rows as $row ) {
    $temp = array();

    foreach( $row as $name => $value ) {
      $temp[ $name ] = $value = mb_convert_encoding( $value, 'auto', 'UTF-8' );
    }

    array_push( $encoded, $temp );
  }

  return $encoded;
}

function db_json( $query ) {
  echo json_encode( utf8_enc( db_fetch_all( db_query( $query ) ) ) );
}

I was seeing some strange results using the ISO-8859-1 accented character set. I switched to UTF-8 and the encoding problems disappeared.

For what it's worth, I have coded getJSON as follows:

  $.getJSON( HOST + 'cat.dhtml', function( data ) {
    var h = '';
    var len = data.length;

    for( var i = 0; i < len; i++ ) {
      h += '<option value="' + data[i].id + '">' + data[i].name + '</option>';
      categories[ data[i].id ] = data[i];
    }

    $('#category').html(h);
  });

It seems to me you receive a parsing error because the response data are wrong decoded and so contain some wrong characters.

You could try to insert in jQuery.ajax an additional parameter

dataFilter : function ( data, type ) {
    alert(data);
    return data;
}

If you will have wrong but different characters for all non-ASCII characters ('ï', 'é' and so on) you can try to replace the wrong encoded characters to the correct characters and return correct encoded data from the dataFilter.

RFC 4627 states that JSON text SHALL be encoded in Unicode, whatever that means, and json.org indicates that all characters be "unicode characters":

  • Encoding

    JSON text SHALL be encoded in Unicode. The default encoding is UTF-8.

    Since the first two characters of a JSON text will always be ASCII characters [RFC0020], it is possible to determine whether an octet stream is UTF-8, UTF-16 (BE or LE), or UTF-32 (BE or LE) by looking at the pattern of nulls in the first four octets.

       00 00 00 xx  UTF-32BE
   00 xx 00 xx  UTF-16BE
   xx 00 00 00  UTF-32LE
   xx 00 xx 00  UTF-16LE
   xx xx xx xx  UTF-8

So if you're transferring JSON and saying that it's ISO-8859-1 then different JSON libraries may interpret the SHALL clause from the RFC that defines JSON in various ways, e.g. by encoding the replacement character or by sniffing the encoding. The best way if obviously to take this to whatever is outside your control and tell them to fix it :-)

Workarounds

One way to work around it is to create a servlet filter that removes all characters that are incompatible with both UTF-8 and ISO-8859-1 and replace them with JSON escapes:

In the following fragment, replace 'é' with '\u00E9' so that any offending ISO-8859-1 character is safely transported in the 7-bits that are identical:

Before: { "a" : "éte" }

After: { "a" : "\u00E9te" }

It's not as legible, but semantically speaking, it's the same, and any good JSON library should treat them identically.

The php function json_encode does not support ISO-8859-1 encoded data.

This article might help you with your problem: http://www.pabloviquez.com/2009/07/json-iso-8859-1-and-utf-8-%E2%80%93-part2/

if you want retrieved data from database you should write these under sentences in the page that send request from ajax page. For example if you write HTML and AJAX code in page "A" and send variable from java code to page "B", write these codes in page "B".
don't forgot your database should be in unicode mode such as "utf8_general_ci". 

mysqli_query ($conn,"set character_set_client='utf8'");
mysqli_query ($conn,"set character_set_results='utf8'");
mysqli_query ($conn,"set collation_connection='utf8_general_ci'");
mysqli_query($conn,"set collation_connection='utf8_persian_ci'");
mysqli_set_charset($conn,"set character_set_results='utf8'") ;
mysqli_set_charset($conn,"set collation_connection='utf8_general_ci'") ;

; I wrote these sentence for Persian language, you can modify it. $conn is a variable for connect to specified table in database of MySQL.

标签
java
jquery
ajax
json
iso-8859-1
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