我需要一个非常非常快的方法来检查字符串是否为JSON。我觉得这不是最好的方式:
function isJson($string) {
return ((is_string($string) &&
(is_object(json_decode($string)) ||
is_array(json_decode($string))))) ? true : false;
}
有没有表演爱好者想改进这种方法?
我需要一个非常非常快的方法来检查字符串是否为JSON。我觉得这不是最好的方式:
function isJson($string) {
return ((is_string($string) &&
(is_object(json_decode($string)) ||
is_array(json_decode($string))))) ? true : false;
}
有没有表演爱好者想改进这种方法?
当前回答
为PHP 5.2兼容性新创建的函数,如果你需要成功解码的数据:
function try_json_decode( $json, & $success = null ){
// non-strings may cause warnings
if( !is_string( $json )){
$success = false;
return $json;
}
$data = json_decode( $json );
// output arg
$success =
// non-null data: success!
$data !== null ||
// null data from 'null' json: success!
$json === 'null' ||
// null data from ' null ' json padded with whitespaces: success!
preg_match('/^\s*null\s*$/', $json );
// return decoded or original data
return $success ? $data : $json;
}
用法:
$json_or_not = ...;
$data = try_json_decode( $json_or_not, $success );
if( $success )
process_data( $data );
else what_the_hell_is_it( $data );
一些测试:
var_dump( try_json_decode( array(), $success ), $success );
// ret = array(0){}, $success == bool(false)
var_dump( try_json_decode( 123, $success ), $success );
// ret = int(123), $success == bool(false)
var_dump( try_json_decode(' ', $success ), $success );
// ret = string(6) " ", $success == bool(false)
var_dump( try_json_decode( null, $success ), $success );
// ret = NULL, $success == bool(false)
var_dump( try_json_decode('null', $success ), $success );
// ret = NULL, $success == bool(true)
var_dump( try_json_decode(' null ', $success ), $success );
// ret = NULL, $success == bool(true)
var_dump( try_json_decode(' true ', $success ), $success );
// ret = bool(true), $success == bool(true)
var_dump( try_json_decode(' "hello" ', $success ), $success );
// ret = string(5) "hello", $success == bool(true)
var_dump( try_json_decode(' {"a":123} ', $success ), $success );
// ret = object(stdClass)#2 (1) { ["a"]=> int(123) }, $success == bool(true)
其他回答
只需添加这个条件:
check if the type is string and then json decode <?php $subject = ['description' => '200 extra contacts','value' => '15','product_code' => 'OS_CONT12']; $subject = '{"description":"200 extra contacts","value":15,"product_code":"OS_CONT12"}'; if(gettype($subject) == 'string'){ $data = json_decode($subject, true); print_r($data); } else{ print_r("saurabh kasmble"); } ?> OUTPUT : Array ( [description] => 200 extra contacts [value] => 15 [product_code] => OS_CONT12 )
这样就可以了:
function isJson($string) {
$decoded = json_decode($string); // decode our JSON string
if ( !is_object($decoded) && !is_array($decoded) ) {
/*
If our string doesn't produce an object or array
it's invalid, so we should return false
*/
return false;
}
/*
If the following line resolves to true, then there was
no error and our JSON is valid, so we return true.
Otherwise it isn't, so we return false.
*/
return (json_last_error() == JSON_ERROR_NONE);
}
if ( isJson($someJsonString) ) {
echo "valid JSON";
} else {
echo "not valid JSON";
}
如其他答案所示,json_last_error()返回来自上一次json_decode()的任何错误。然而,在一些边缘用例中,仅使用这个功能还不够全面。例如,如果你json_decode()一个整数(例如:123),或者一个没有空格或其他字符的数字字符串(例如:“123”),json_last_error()函数将不会捕获错误。
为了解决这个问题,我添加了一个额外的步骤,以确保json_decode()的结果是一个对象或数组。如果不是,则返回false。
要查看具体操作,请查看以下两个示例:
只使用json_last_error()检查 首先检查对象/数组
下面是我创建的一个简单的性能函数(在使用json_decode处理更大的字符串之前使用基本的字符串验证):
function isJson($string) {
$response = false;
if (
is_string($string) &&
($string = trim($string)) &&
($stringLength = strlen($string)) &&
(
(
stripos($string, '{') === 0 &&
(stripos($string, '}', -1) + 1) === $stringLength
) ||
(
stripos($string, '[{') === 0 &&
(stripos($string, '}]', -1) + 2) === $stringLength
)
) &&
($decodedString = json_decode($string, true)) &&
is_array($decodedString)
) {
$response = true;
}
return $response;
}
你真正需要做的就是…
if (is_object(json_decode($MyJSONArray)))
{
... do something ...
}
这个请求甚至不需要一个单独的函数。只需将is_object包装在json_decode周围,然后继续。似乎这个解决方案让人们花了太多心思。
使用PHPBench和下面的类,得到了以下结果:
<?php
declare(strict_types=1);
/**
* @Revs(1000)
* @Iterations(100)
*/
class BenchmarkJson
{
public function benchCatchValid(): bool
{
$validJson = '{"validJson":true}';
try {
json_decode($validJson, true, 512, JSON_THROW_ON_ERROR);
return true;
} catch(\JsonException $exception) {}
return false;
}
public function benchCatchInvalid(): bool
{
$invalidJson = '{"invalidJson"';
try {
json_decode($invalidJson, true, 512, JSON_THROW_ON_ERROR);
return true;
} catch(\JsonException $exception) {}
return false;
}
public function benchLastErrorValid(): bool
{
$validJson = '{"validJson":true}';
json_decode($validJson, true);
return (json_last_error() === JSON_ERROR_NONE);
}
public function benchLastErrorInvalid(): bool
{
$invalidJson = '{"invalidJson"';
json_decode($invalidJson, true);
return (json_last_error() === JSON_ERROR_NONE);
}
public function benchNullValid(): bool
{
$validJson = '{"validJson":true}';
return (json_decode($validJson, true) !== null);
}
public function benchNullInvalid(): bool
{
$invalidJson = '{"invalidJson"';
return (json_decode($invalidJson, true) !== null);
}
}
6 subjects, 600 iterations, 6,000 revs, 0 rejects, 0 failures, 0 warnings
(best [mean mode] worst) = 0.714 [1.203 1.175] 1.073 (μs)
⅀T: 721.504μs μSD/r 0.089μs μRSD/r: 7.270%
suite: 1343ab9a3590de6065bc0bc6eeb344c9f6eba642, date: 2020-01-21, stime: 12:50:14
+---------------+-----------------------+-----+------+-----+------------+---------+---------+---------+---------+---------+--------+-------+
| benchmark | subject | set | revs | its | mem_peak | best | mean | mode | worst | stdev | rstdev | diff |
+---------------+-----------------------+-----+------+-----+------------+---------+---------+---------+---------+---------+--------+-------+
| BenchmarkJson | benchCatchValid | 0 | 1000 | 100 | 2,980,168b | 0.954μs | 1.032μs | 1.016μs | 1.428μs | 0.062μs | 6.04% | 1.33x |
| BenchmarkJson | benchCatchInvalid | 0 | 1000 | 100 | 2,980,184b | 2.033μs | 2.228μs | 2.166μs | 3.001μs | 0.168μs | 7.55% | 2.88x |
| BenchmarkJson | benchLastErrorValid | 0 | 1000 | 100 | 2,980,184b | 1.076μs | 1.195μs | 1.169μs | 1.616μs | 0.083μs | 6.97% | 1.54x |
| BenchmarkJson | benchLastErrorInvalid | 0 | 1000 | 100 | 2,980,184b | 0.785μs | 0.861μs | 0.863μs | 1.132μs | 0.056μs | 6.54% | 1.11x |
| BenchmarkJson | benchNullValid | 0 | 1000 | 100 | 2,980,168b | 0.985μs | 1.124μs | 1.077μs | 1.731μs | 0.114μs | 10.15% | 1.45x |
| BenchmarkJson | benchNullInvalid | 0 | 1000 | 100 | 2,980,184b | 0.714μs | 0.775μs | 0.759μs | 1.073μs | 0.049μs | 6.36% | 1.00x |
+---------------+-----------------------+-----+------+-----+------------+---------+---------+---------+---------+---------+--------+-------+
结论:检查json是否有效的最快方法是返回json_decode($json, true) !== null)。