url encode的概念和实现？

Question

1. 为什么要进行url encode（或者说url encode的意义）？

2. 如何实现url encode？

更新

答案最好：

• 通俗易懂，题主是看不了rfc文档才来提问的。

• 详细一些，为了安全，为了传输数据方便，这种回答过于简单，最好能详细铺开表达一下。

Answer 1

建议楼主去下一本《Http权威指南》来看看。
就看 2.4 节：各种令人头痛的字符
看图吧~

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Reserved and restricted characters

Character              Reservation/Restriction
 
%                      Reserved as escape token for encoded characters
 
/                      Reserved for delimiting splitting up path segments in the path component 
 
.                      Reserved in the path component
 
..                     Reserved in the path component
 
#                      Reserved as the fragment delimiter
 
?                      Reserved as the query-string delimiter
 
;                      Reserved as the params delimiter
 
:                      Reserved to delimit the scheme, user/password, and host/port components 
 
$ , +                  Reserved
 
@ & =                  Reserved because they have special meaning in the context of some schemes 
 
{ } | \ ^ ~ [ ] `     Restricted because of unsafe handling by various transport agents, such as gateways 
 
< > "                  Unsafe; should be encoded because these characters often have meaning outside the scope of the URL, such as delimiting the URL itself in a document (e.g., "http://www.joes-hardware.com") 
 
0x00-0x1F, 0x7F        Restricted; characters within these hex ranges fall within the nonprintable section of the US-ASCII character set 
 
> 0x7F                 Restricted; characters whose hex values fall within this range do not fall within the 7-bit range of the US-ASCII character set 

Answer 2

encode通常是传输或存储的需要。

具体概念和设计可以查看 rfc文档