验证 URL

过滤网址时，filter_var() 将返回已过滤的数据（在本例中为 URL），如果找不到有效的网址，则返回 false：

网址：example.com

var_dump(filter_var('example.com', FILTER_VALIDATE_URL));
var_dump(filter_var('example.com', FILTER_VALIDATE_URL, FILTER_FLAG_SCHEME_REQUIRED));
var_dump(filter_var('example.com', FILTER_VALIDATE_URL, FILTER_FLAG_HOST_REQUIRED));
var_dump(filter_var('example.com', FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED));
var_dump(filter_var('example.com', FILTER_VALIDATE_URL, FILTER_FLAG_QUERY_REQUIRED));

结果：

bool(false)
bool(false)
bool(false)
bool(false)
bool(false)

网址：http://example.com

var_dump(filter_var('http://example.com', FILTER_VALIDATE_URL));
var_dump(filter_var('http://example.com', FILTER_VALIDATE_URL, FILTER_FLAG_SCHEME_REQUIRED));
var_dump(filter_var('http://example.com', FILTER_VALIDATE_URL, FILTER_FLAG_HOST_REQUIRED));
var_dump(filter_var('http://example.com', FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED));
var_dump(filter_var('http://example.com', FILTER_VALIDATE_URL, FILTER_FLAG_QUERY_REQUIRED));

结果：

string(18) "http://example.com"
string(18) "http://example.com"
string(18) "http://example.com"
bool(false)
bool(false)

网址：http://www.example.com

var_dump(filter_var('http://www.example.com', FILTER_VALIDATE_URL));
var_dump(filter_var('http://www.example.com', FILTER_VALIDATE_URL, FILTER_FLAG_SCHEME_REQUIRED));
var_dump(filter_var('http://www.example.com', FILTER_VALIDATE_URL, FILTER_FLAG_HOST_REQUIRED));
var_dump(filter_var('http://www.example.com', FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED));
var_dump(filter_var('http://www.example.com', FILTER_VALIDATE_URL, FILTER_FLAG_QUERY_REQUIRED));

结果：

string(22) "http://www.example.com"
string(22) "http://www.example.com"
string(22) "http://www.example.com"
bool(false)
bool(false)

网址：http://www.example.com/path/to/dir/

var_dump(filter_var('http://www.example.com/path/to/dir/', FILTER_VALIDATE_URL));
var_dump(filter_var('http://www.example.com/path/to/dir/', FILTER_VALIDATE_URL, FILTER_FLAG_SCHEME_REQUIRED));
var_dump(filter_var('http://www.example.com/path/to/dir/', FILTER_VALIDATE_URL, FILTER_FLAG_HOST_REQUIRED));
var_dump(filter_var('http://www.example.com/path/to/dir/', FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED));
var_dump(filter_var('http://www.example.com/path/to/dir/', FILTER_VALIDATE_URL, FILTER_FLAG_QUERY_REQUIRED));

结果：

string(35) "http://www.example.com/path/to/dir/"
string(35) "http://www.example.com/path/to/dir/"
string(35) "http://www.example.com/path/to/dir/"
string(35) "http://www.example.com/path/to/dir/"
bool(false)

网址：http://www.example.com/path/to/dir/index.php

var_dump(filter_var('http://www.example.com/path/to/dir/index.php', FILTER_VALIDATE_URL));
var_dump(filter_var('http://www.example.com/path/to/dir/index.php', FILTER_VALIDATE_URL, FILTER_FLAG_SCHEME_REQUIRED));
var_dump(filter_var('http://www.example.com/path/to/dir/index.php', FILTER_VALIDATE_URL, FILTER_FLAG_HOST_REQUIRED));
var_dump(filter_var('http://www.example.com/path/to/dir/index.php', FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED));
var_dump(filter_var('http://www.example.com/path/to/dir/index.php', FILTER_VALIDATE_URL, FILTER_FLAG_QUERY_REQUIRED));

结果：

string(44) "http://www.example.com/path/to/dir/index.php"
string(44) "http://www.example.com/path/to/dir/index.php"
string(44) "http://www.example.com/path/to/dir/index.php"
string(44) "http://www.example.com/path/to/dir/index.php"
bool(false)

网址：http://www.example.com/path/to/dir/index.php?test=y

var_dump(filter_var('http://www.example.com/path/to/dir/index.php?test=y', FILTER_VALIDATE_URL));
var_dump(filter_var('http://www.example.com/path/to/dir/index.php?test=y', FILTER_VALIDATE_URL, FILTER_FLAG_SCHEME_REQUIRED));
var_dump(filter_var('http://www.example.com/path/to/dir/index.php?test=y', FILTER_VALIDATE_URL, FILTER_FLAG_HOST_REQUIRED));
var_dump(filter_var('http://www.example.com/path/to/dir/index.php?test=y', FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED));
var_dump(filter_var('http://www.example.com/path/to/dir/index.php?test=y', FILTER_VALIDATE_URL, FILTER_FLAG_QUERY_REQUIRED));

结果：

string(51) "http://www.example.com/path/to/dir/index.php?test=y"
string(51) "http://www.example.com/path/to/dir/index.php?test=y"
string(51) "http://www.example.com/path/to/dir/index.php?test=y"
string(51) "http://www.example.com/path/to/dir/index.php?test=y"
string(51) "http://www.example.com/path/to/dir/index.php?test=y"

警告 ：你必须检查协议以保护你免受 XSS 攻击：

var_dump(filter_var('javascript://comment%0Aalert(1)', FILTER_VALIDATE_URL));
// string(31) "javascript://comment%0Aalert(1)"