对于老的php版本是没有json_encode 和json_decode函数的，但是又想使用这个功能。下边就是一个用php代码写的json encode 和decode 的函数。
function fromJSON ( $json, $assoc = false ) {
/* by default we don't tolerate ' as string delimiters
if you need this, then simply change the comments on
the following lines: */
$matchString = '/(".*?(?<!\\\\)"|\'.*?(?<!\\\\)\')/';
//$matchString = '/".*?(?<!\\\\)"/';
// safety / validity test
$t = preg_replace( $matchString, '', $json );
$t = preg_replace( '/[,:{}\[\]0-9.\-+Eaeflnr-u \n\r\t]/', '', $t );
if ($t != '') { return null; }
// build to/from hashes for all strings in the structure
$s2m = array();
$m2s = array();
preg_match_all( $matchString, $json, $m );
foreach ($m[0] as $s) {
$hash = '"' . md5( $s ) . '"';
$s2m[$s] = $hash;
$m2s[$hash] = str_replace( '$', '\$', $s ); // prevent $ magic
}
// hide the strings
$json = strtr( $json, $s2m );
// convert JS notation to PHP notation
$a = ($assoc) ? '' : '(object) ';
$json = strtr( $json,
array(
':' => '=>',
'[' => 'array(',
'{' => "{$a}array(",
']' => ')',
'}' => ')'
)
);
// remove leading zeros to prevent incorrect type casting
$json = preg_replace( '~([\s\(,>])(-?)0~', '$1$2', $json );
// return the strings
$json = strtr( $json, $m2s );
/* "eval" string and return results.
As there is no try statement in PHP4, the trick here
is to suppress any parser errors while a function is
built and then run the function if it got made. */
$f = @create_function( '', "return {$json};" );
$r = ($f) ? $f() : null;
// free mem (shouldn't really be needed, but it's polite)
unset( $s2m ); unset( $m2s ); unset( $f );
return $r;
}
/**
* Encodes a PHP variable into a JSON string.
* @param mixed $value A PHP variable to be encoded.
*/
function toJSON ( $value ) {
if ($value === null) { return 'null'; }; // gettype fails on null?
$out = '';
$esc = "\"\\/\n\r\t" . chr( 8 ) . chr( 12 ); // escaped chars
$l = '.'; // decimal point
switch ( gettype( $value ) )
{
case 'boolean':
$out .= $value ? 'true' : 'false';
break;
case 'float':
case 'double':
// PHP uses the decimal point of the current locale but JSON expects %x2E
$l = localeconv();
$l = $l['decimal_point'];
// fallthrough...
case 'integer':
$out .= str_replace( $l, '.', $value ); // what, no getlocale?
break;
case 'array':
// if array only has numeric keys, and is sequential... ?
for ($i = 0; ($i < count( $value ) && isset( $value[$i]) ); $i++);
if ($i === count($value)) {
// it's a "true" array... or close enough
$out .= '[' . implode(',', array_map('toJSON', $value)) . ']';
break;
}
// fallthrough to object for associative arrays...
case 'object':
$arr = is_object($value) ? get_object_vars($value) : $value;
$b = array();
foreach ($arr as $k => $v) {
$b[] = '"' . addcslashes($k, $esc) . '":' . toJSON($v);
}
$out .= '{' . implode( ',', $b ) . '}';
break;
default: // anything else is treated as a string
return '"' . addcslashes($value, $esc) . '"';
break;
}
return $out;
}