《PHP教程：php語言中使用json的技巧及json的實現代碼詳解》要點：
本文介紹了PHP教程：php語言中使用json的技巧及json的實現代碼詳解，希望對您有用。如果有疑問，可以聯系我們。
PHP應用目前,JSON已經成為最流行的數據交換格式之一,各大網站的API幾乎都支持它.
PHP應用我寫過一篇《數據類型和JSON格式》,探討它的設計思想.本日,我想總結一下PHP語言對它的支持,這是開發互聯網應用程序(特別是編寫API)必須了解的知識.
PHP應用從5.2版本開始,PHP原生提供json_encode()和json_decode()函數,前者用于編碼,后者用于解碼.
PHP應用一、json_encode()
PHP應用該函數主要用來將數組和對象,轉換為json格式.先看一個數組轉換的例子：
PHP應用
$arr = array ('a'=>1,'b'=>2,'c'=>3,'d'=>4,'e'=>5);
echo json_encode($arr);
PHP應用結果為
PHP應用{"a":1,"b":2,"c":3,"d":4,"e":5}
PHP應用再看一個對象轉換的例子：
PHP應用
$obj->body = 'another post';
$obj->id = 21;
$obj->approved = true;
$obj->favorite_count = 1;
$obj->status = NULL;
echo json_encode($obj);
PHP應用結果為
PHP應用
{
"body":"another post",
"id":21,
"approved":true,
"favorite_count":1,
"status":null
}
PHP應用由于json只接受utf-8編碼的字符,所以json_encode()的參數必需是utf-8編碼,否則會得到空字符或者null.當中文使用GB2312編碼,或者外文使用ISO-8859-1編碼的時候,這一點要特別注意.
PHP應用二、索引數組和關聯數組
PHP應用PHP支持兩種數組,一種是只保留"值"(value)的索引數組(indexed array),另一種是保留"名值對"(name/value)的關聯數組(associative array).
PHP應用由于javascript不支持關聯數組,所以json_encode()只將索引數組(indexed array)轉為數組格式,而將關聯數組(associative array)轉為對象格式.
PHP應用好比,現在有一個索引數組
PHP應用
$arr = Array('one', 'two', 'three');
echo json_encode($arr);
PHP應用結果為：
PHP應用["one","two","three"]
PHP應用如果將它改為關聯數組：
PHP應用
$arr = Array('1'=>'one', '2'=>'two', '3'=>'three');
echo json_encode($arr);
PHP應用結果就變了：
PHP應用
{"1":"one","2":"two","3":"three"}
PHP應用注意,數據格式從"[]"(數組)釀成了"{}"(對象).
PHP應用如果你必要將"索引數組"強制轉化成"對象",可以這樣寫
PHP應用
json_encode( (object)$arr );
PHP應用或者
PHP應用
json_encode ( $arr, JSON_FORCE_OBJECT );
PHP應用三、類(class)的轉換
PHP應用下面是一個PHP的類：
PHP應用
class Foo {
const ERROR_CODE = '404';
public $public_ex = 'this is public';
private $private_ex = 'this is private!';
protected $protected_ex = 'this should be protected';
public function getErrorCode() {
return self::ERROR_CODE;
}
}
PHP應用現在,對這個類的實例進行json轉換：
PHP應用
$foo = new Foo;
$foo_json = json_encode($foo);
echo $foo_json;
PHP應用輸出結果是
PHP應用{"public_ex":"this is public"}
PHP應用可以看到,除了公開變量(public),其他東西(常量、私有變量、辦法等等)都遺失了.
PHP應用四、json_decode()
PHP應用該函數用于將json文本轉換為相應的PHP數據布局.下面是一個例子：
PHP應用
$json = '{"foo": 12345}';
$obj = json_decode($json);
print $obj->{'foo'}; // 12345
PHP應用通常情況下,json_decode()總是返回一個PHP對象,而不是數組.好比：
PHP應用
$json = '{"a":1,"b":2,"c":3,"d":4,"e":5}';
var_dump(json_decode($json));
PHP應用結果便是生成一個PHP對象：
PHP應用
object(stdClass)#1 (5) {
["a"] => int(1)
["b"] => int(2)
["c"] => int(3)
["d"] => int(4)
["e"] => int(5)
}
PHP應用如果想要強制生成PHP關聯數組,json_decode()必要加一個參數true：
PHP應用
$json = '{"a":1,"b":2,"c":3,"d":4,"e":5}';
var_dump(json_decode($json,true));
PHP應用結果就生成了一個關聯數組：
PHP應用
array(5) {
["a"] => int(1)
["b"] => int(2)
["c"] => int(3)
["d"] => int(4)
["e"] => int(5)
}
PHP應用五、json_decode()的常見差錯
PHP應用下面三種json寫法都是錯的,你能看出錯在哪里嗎?
PHP應用
$bad_json = "{ 'bar': 'baz' }";
$bad_json = '{ bar: "baz" }';
$bad_json = '{ "bar": "baz", }';
PHP應用對這三個字符串執行json_decode()都將返回null,而且報錯.
PHP應用第一個的錯誤是,json的分隔符(delimiter)只允許使用雙引號,不能使用單引號.第二個的錯誤是,json名值對的"名"(冒號左邊的部分),任何情況下都必需使用雙引號.第三個的錯誤是,最后一個值之后不能添加逗號(trailing comma).
PHP應用另外,json只能用來表現對象(object)和數組(array),如果對一個字符串或數值使用json_decode(),將會返回null.
PHP應用
var_dump(json_decode("Hello World")); //null
PHP應用下面給大家介紹哦php語言的json實現
PHP應用由于開發一個ajax file manager for web開源項目,數據交換使用的json格式,后來發現在低版本的php上運行會有問題,仔細調試發現json_decode和json_encode無法正常工作,于是查閱資料,發現低版本的php沒有實現這兩個函數,為了兼容性,我只好自己實現一個php版的json編碼解碼代碼,并保證和json2.js的一致,測試調試并通過,現在將其頒布出來,供有相同需求的同學使用：
PHP應用
<?php
/* * ****************************************************************************
* $base: $
*
* $Author: $
* Berlin Qin
*
* $History: base.js $
* Berlin Qin // created
*
* $contacted
* webfmt@gmail.com
* www.webfmt.com
*
* *************************************************************************** */
/* ===========================================================================
* license
*
* 、Open Source Licenses
* webfmt is distributed under the GPL, LGPL and MPL open source licenses.
* This triple copyleft licensing model avoids incompatibility with other open source licenses.
* These Open Source licenses are specially indicated for:
* Integrating webfmt into Open Source software;
* Personal and educational use of webfmt;
* Integrating webfmt in commercial software,
* taking care of satisfying the Open Source licenses terms,
* while not able or interested on supporting webfmt and its development.
*
* 、Commercial License C fbis source Closed Distribution License - CDL
* For many companies and products, Open Source licenses are not an option.
* This is why the fbis source Closed Distribution License (CDL) has been introduced.
* It is a non-copyleft license which gives companies complete freedom
* when integrating webfmt into their products and web sites.
* This license offers a very flexible way to integrate webfmt in your commercial application.
* These are the main advantages it offers over an Open Source license:
* Modifications and enhancements doesn't need to be released under an Open Source license;
* There is no need to distribute any Open Source license terms alongside with your product
* and no reference to it have to be done;
* No references to webfmt have to be done in any file distributed with your product;
* The source code of webfmt doesn't have to be distributed alongside with your product;
* You can remove any file from webfmt when integrating it with your product.
* The CDL is a lifetime license valid for all releases of webfmt published during
* and before the year following its purchase.
* It's valid for webfmt releases also. It includes year of personal e-mail support.
*
* ************************************************************************************************************************************************* */
function jsonDecode($json)
{
$result = array();
try
{
if (PHP_VERSION_ID > )
{
$result = (array) json_decode($json);
}
else
{
$json = str_replace(array("\\\\", "\\\""), array("", ""), $json);
$parts = preg_split("@(\"[^\"]*\")|([\[\]\{\},:])|\s@is", $json, -, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);
foreach ($parts as $index => $part)
{
if (strlen($part) == )
{
switch ($part)
{
case "[":
case "{":
$parts[$index] = "array(";
break;
case "]":
case "}":
$parts[$index] = ")";
break;
case ":":
$parts[$index] = "=>";
break;
case ",":
break;
default:
break;
}
}
}
$json = str_replace(array("", "", "$"), array("\\\\", "\\\"", "\\$"), implode("", $parts));
$result = eval("return $json;");
}
}
catch (Exception $e)
{
$result = array("error" => $e->getCode());
}
return $result;
}
function valueTostr($val)
{
if (is_string($val))
{
$val = str_replace('\"', "\\\"", $val);
$val = str_replace("\\", "\\\\", $val);
$val = str_replace("/", "\\/", $val);
$val = str_replace("\t", "\\t", $val);
$val = str_replace("\n", "\\n", $val);
$val = str_replace("\r", "\\r", $val);
$val = str_replace("\b", "\\b", $val);
$val = str_replace("\f", "\\f", $val);
return '"' . $val . '"';
}
elseif (is_int($val))
return sprintf('%d', $val);
elseif (is_float($val))
return sprintf('%F', $val);
elseif (is_bool($val))
return ($val ? 'true' : 'false');
else
return 'null';
}
function jsonEncode($arr)
{
$result = "{}";
try
{
if (PHP_VERSION_ID > )
{
$result = json_encode($arr);
}
else
{
$parts = array();
$is_list = false;
if (!is_array($arr))
{
$arr = (array) $arr;
}
$end = count($arr) - ;
if (count($arr) > )
{
if (is_numeric(key($arr)))
{
$result = "[";
for ($i = ; $i < count($arr); $i++)
{
if (is_array($arr[$i]))
{
$result = $result . jsonEncode($arr[$i]);
}
else
{
$result = $result . valueTostr($arr[$i]);
}
if ($i != $end)
{
$result = $result . ",";
}
}
$result = $result . "]";
}
else
{
$result = "{";
$i = ;
foreach ($arr as $key => $value)
{
$result = $result . '"' . $key . '":';
if (is_array($value))
{
$result = $result . jsonEncode($value);
}
else
{
$result = $result . valueTostr($value);
}
if ($i != $end)
{
$result = $result . ",";
}
$i++;
}
$result = $result . "}";
}
}
else
{
$result = "[]";
}
}
}
catch (Exception $e)
{
}
return $result;
}
?>
PHP應用如果使用過程有什么問題,可以給我email.歡迎大家指出差錯!
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