php语言中使用json的技巧及json的实现代码详解
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《php语言中使用json的技巧及json的实现代码详解》要点： PHP应用目前,JSON已经成为最流行的数据交换格式之一,各大网站的API几乎都支持它. 我写过一篇《数据类型和JSON格式》,探讨它的设计思想.本日,我想总结一下PHP语言对它的支持,这是开发互联网应用程序(特别是编写API)必须了解的知识. 从5.2版本开始,PHP原生提供json_encode()和json_decode()函数,前者用于编码,后者用于解码. 一、json_encode() 该函数主要用来将数组和对象,转换为json格式.先看一个数组转换的例子：
$arr = array ('a'=>1,'b'=>2,'c'=>3,'d'=>4,'e'=>5);
echo json_encode($arr);
结果为 {"a":1,"b":2,"c":3,"d":4,"e":5} 再看一个对象转换的例子： $obj->body = 'another post'; $obj->id = 21; $obj->approved = true; $obj->favorite_count = 1; $obj->status = NULL; echo json_encode($obj); 结果为
{
"body":"another post",
"id":21, "approved":true, "favorite_count":1, "status":null
}
由于json只接受utf-8编码的字符,所以json_encode()的参数必需是utf-8编码,否则会得到空字符或者null.当中文使用GB2312编码,或者外文使用ISO-8859-1编码的时候,这一点要特别注意. 二、索引数组和关联数组 PHP支持两种数组,一种是只保留"值"(value)的索引数组(indexed array),另一种是保留"名值对"(name/value)的关联数组(associative array). 由于javascript不支持关联数组,所以json_encode()只将索引数组(indexed array)转为数组格式,而将关联数组(associative array)转为对象格式. 好比,现在有一个索引数组
$arr = Array('one','two','three');
echo json_encode($arr);
结果为： ["one","two","three"] 如果将它改为关联数组：
$arr = Array('1'=>'one','2'=>'two','3'=>'three');
echo json_encode($arr);
结果就变了：
{"1":"one","2":"two","3":"three"}
注意,数据格式从"[]"(数组)酿成了"{}"(对象). 如果你必要将"索引数组"强制转化成"对象",可以这样写 json_encode( (object)$arr ); 或者 json_encode ( $arr,JSON_FORCE_OBJECT ); 三、类(class)的转换 下面是一个PHP的类：
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;
}
}
现在,对这个类的实例进行json转换： $foo = new Foo; $foo_json = json_encode($foo); echo $foo_json; 输出结果是 {"public_ex":"this is public"} 可以看到,除了公开变量(public),其他东西(常量、私有变量、办法等等)都遗失了. 四、json_decode() 该函数用于将json文本转换为相应的PHP数据布局.下面是一个例子：
$json = '{"foo": 12345}';
$obj = json_decode($json);
print $obj->{'foo'}; // 12345
通常情况下,json_decode()总是返回一个PHP对象,而不是数组.好比：
$json = '{"a":1,"e":5}';
var_dump(json_decode($json));
结果便是生成一个PHP对象：
object(stdClass)#1 (5) {
["a"] => int(1)
["b"] => int(2)
["c"] => int(3)
["d"] => int(4)
["e"] => int(5)
}
如果想要强制生成PHP关联数组,json_decode()必要加一个参数true：
$json = '{"a":1,"e":5}';
var_dump(json_decode($json,true));
结果就生成了一个关联数组：
array(5) {
["a"] => int(1)
["b"] => int(2)
["c"] => int(3)
["d"] => int(4)
["e"] => int(5)
}
五、json_decode()的常见差错 下面三种json写法都是错的,你能看出错在哪里吗?
$bad_json = "{ 'bar': 'baz' }";
$bad_json = '{ bar: "baz" }';
$bad_json = '{ "bar": "baz",}';
对这三个字符串执行json_decode()都将返回null,而且报错. 第一个的错误是,json的分隔符(delimiter)只允许使用双引号,不能使用单引号.第二个的错误是,json名值对的"名"(冒号左边的部分),任何情况下都必需使用双引号.第三个的错误是,最后一个值之后不能添加逗号(trailing comma). 另外,json只能用来表现对象(object)和数组(array),如果对一个字符串或数值使用json_decode(),将会返回null.
var_dump(json_decode("Hello World")); //null
下面给大家介绍哦php语言的json实现 由于开发一个ajax file manager for web开源项目,数据交换使用的json格式,后来发现在低版本的php上运行会有问题,仔细调试发现json_decode和json_encode无法正常工作,于是查阅资料,发现低版本的php没有实现这两个函数,为了兼容性,我只好自己实现一个php版的json编码解码代码,并保证和json2.js的一致,测试调试并通过,现在将其颁布出来,供有相同需求的同学使用：
<?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;
}
?>
如果使用过程有什么问题,可以给我email.欢迎大家指出差错! 编程之家培训学院每天发布《php语言中使用json的技巧及json的实现代码详解》等实战技能，PHP、MYSQL、LINUX、APP、JS,CSS全面培养人才。 （编辑：李大同） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |