PHP中json的用法
作者:admin 日期:2012-04-07
从事WEB相关开发的人员相信对json应该不会陌生，我在这里也无需多说了，可以直接看官方的文档。
JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate. It is based on a subset of the JavaScript Programming Language, Standard ECMA-262 3rd Edition - December 1999. JSON is a text format that is completely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. These properties make JSON an ideal data-interchange language.Via
JSON(JavaScript Object Notation) 是一种轻量级的数据交换格式。易于人阅读和编写。同时也易于机器解析和生成。它基于JavaScript（Standard ECMA-262 3rd Edition - December 1999）的一个子集。 JSON采用完全独立于语言的文本格式，但是也使用了类似于C语言家族的习惯（包括C, C++, C#, Java, JavaScript, Perl, Python等）。这些特性使JSON成为理想的数据交换语言。Via
下面我们来进行2个测试:
测试前的2项配置如下：
; Magic quotes for incoming GET/POST/Cookie data.
magic_quotes_gpc = On
; Magic quotes for runtime-generated data, e.g. data from SQL, from exec(), etc.
magic_quotes_runtime = Off
1.测试一
字符串$str中含有一些特殊字符，如"、'及\
$str = 'ok":\'\\';
echo "str: $str\n";
$str1 = json_encode($str);
echo 'json_encode:' . $str1 . "\n";
$str2 = json_decode($str1);
echo 'json_decode:' . $str2 . "\n";
输出如下，我是在linux的命令行下运行的，json_encode以后在字符串的两边加上了双引号(")，
"变成了\"，\变成了\\，'还是'。在json_decode以后内容可以变为json_encode以前的内容。
此时有个小问题要注意一下，如果此数据是要返回给前端的，特殊处理需要单独处理一下。
例如name:"ok":'\"这样肯定不行，js肯定会报错的，正确的方法是如果觉得返回的内容可能有特符字符，用addslashes处理一下就行了。
如
$name = "ok\":'\\";
$name = addslashes($name);
{name: "ok\":'\\"}
str: ok":'\
json_encode:"ok\":'\\"
json_decode:ok":'\
2.测试二
2与1中是差不多的，只不过加了一个addslashes的处理。
$str = 'ok":\'\\';
echo "str: $str\n";
$str = addslashes($str);
echo "str: $str\n";
$str1 = json_encode($str);
echo 'json_encode:' . $str1 . "\n";
$str2 = json_decode($str1);
echo 'json_decode:' . $str2 . "\n";
输出如下：
str: ok":'\
str: ok\":\'\\
json_encode:"ok\\\":\\'\\\\"
json_decode:ok\":\'\\
3.json关于中文的处理
a.不能处理GB编码，所有的GB编码都会替换成空字符.
b.utf8编码的中文被编码成unicode编码，相当于javascript的escape函数处理的结果.
utf8编码的中文会被编码为unicode编码，取出时用json_decode解码后不用作任何处理后在网页上可以正常显示中文。
telnet localhost 1977
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
get top_song
VALUE top_song 0 1037
[{"songid":"154","songname":"\u575a\u6301\u5230\u5e95","sengername":"\u963f\u675c"},{"songid":"52715","songname":"\u5929\u8def","sengername":"\u97e9\u7ea2"},{"songid":"66969","songname":"\u72af\u9519 - \u65af\u7434\u9ad8\u4e3d\/\u987e\u5cf0","sengername":"\u65af\u7434\u9ad8\u4e3d"},{"songid":"264315","songname":"\u4e0b\u4e2a\uff0c\u8def\u53e3\uff0c\u89c1","sengername":"\u674e\u5b87\u6625"},{"songid":"264316","songname":"\u6211\u60f3\u6211\u662f\u4f60\u7684\u5973\u4eba","sengername":"\u5c1a\u96ef\u5a55"},{"songid":"264317","songname":"\u7231\u6068\u6062\u6062","sengername":"\u5468\u8fc5"},{"songid":"264318","songname":"\u6211\u5fc3\u662f\u6d77\u6d0b","sengername":"\u8521\u7434"},{"songid":"264372","songname":"\u4e0d\u8981\u5728\u6211\u5bc2\u5bde\u7684\u65f6\u5019\u8bf4\u7231\u6211","sengername":"T.R.Y"},{"songid":"265463","songname":"\u4e0d\u662f\u56e0\u4e3a\u5bc2\u5bde\u624d\u60f3\u4f60","sengername":"TRY"},{"songid":"265681","songname":"\u5e78\u798f\u62cd\u624b\u6b4c","sengername":"\u7cbe\u9009\u513f\u7ae5\u6b4c\u66f2"}]
END
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