(PHP 5 >= 5.3.0)
json_last_error — 返回最后发生的错误
如果有，返回 JSON 编码解码时最后发生的错误。
此函数没有参数。
返回一个整型（integer），这个值会是以下的常量之一：
| 常量 | 含义 | 可用性 |
|---|---|---|
JSON_ERROR_NONE |
没有错误发生 | |
JSON_ERROR_DEPTH |
到达了最大堆栈深度 | |
JSON_ERROR_STATE_MISMATCH |
无效或异常的 JSON | |
JSON_ERROR_CTRL_CHAR |
控制字符错误，可能是编码不对 | |
JSON_ERROR_SYNTAX |
语法错误 | |
JSON_ERROR_UTF8 |
异常的 UTF-8 字符，也许是因为不正确的编码。 | PHP 5.3.3 |
Example #1 json_last_error() 例子
<?php
// 一个有效的 json 字符串
$json[] = '{"Organization": "PHP Documentation Team"}';
// 一个无效的 json 字符串会导致一个语法错误，在这个例子里我们使用 ' 代替了 " 作为引号
$json[] = "{'Organization': 'PHP Documentation Team'}";
foreach ($json as $string) {
echo 'Decoding: ' . $string;
json_decode($string);
switch (json_last_error()) {
case JSON_ERROR_NONE:
echo ' - No errors';
break;
case JSON_ERROR_DEPTH:
echo ' - Maximum stack depth exceeded';
break;
case JSON_ERROR_STATE_MISMATCH:
echo ' - Underflow or the modes mismatch';
break;
case JSON_ERROR_CTRL_CHAR:
echo ' - Unexpected control character found';
break;
case JSON_ERROR_SYNTAX:
echo ' - Syntax error, malformed JSON';
break;
case JSON_ERROR_UTF8:
echo ' - Malformed UTF-8 characters, possibly incorrectly encoded';
break;
default:
echo ' - Unknown error';
break;
}
echo PHP_EOL;
}
?>
以上例程会输出：
Decoding: {"Organization": "PHP Documentation Team"} - No errors
Decoding: {'Organization': 'PHP Documentation Team'} - Syntax error, malformed JSON
Example #2 json_encode() 的 json_last_error()
<?php
// 无效的 UTF8 序列
$text = "\xB1\x31";
$json = json_encode($text);
$error = json_last_error();
var_dump($json, $error === JSON_ERROR_UTF8);
?>
以上例程会输出：
string(4) "null" bool(true)
jimmetry at gmail dot com (2011-11-23 21:16:31)
While this can obviously change between versions, the current error codes are as follows:
0 = JSON_ERROR_NONE
1 = JSON_ERROR_DEPTH
2 = JSON_ERROR_STATE_MISMATCH
3 = JSON_ERROR_CTRL_CHAR
4 = JSON_ERROR_SYNTAX
5 = JSON_ERROR_UTF8
I'm only posting these for people who may be trying to understand why specific JSON files are not being decoded. Please do not hard-code these numbers into an error handler routine.
lior at mytopia dot com (2009-03-09 05:17:14)
For those of you who prefer a more object oriented approach (as I do), here is a fairly simple wrapper that handles errors using exceptions:
<?php
class JSON
{
public static function Encode($obj)
{
return json_encode($obj);
}
public static function Decode($json, $toAssoc = false)
{
$result = json_decode($json, $toAssoc);
switch(json_last_error())
{
case JSON_ERROR_DEPTH:
$error = ' - Maximum stack depth exceeded';
break;
case JSON_ERROR_CTRL_CHAR:
$error = ' - Unexpected control character found';
break;
case JSON_ERROR_SYNTAX:
$error = ' - Syntax error, malformed JSON';
break;
case JSON_ERROR_NONE:
default:
$error = '';
}
if (!empty($error))
throw new Exception('JSON Error: '.$error);
return $result;
}
}
?>