php生成唯一数字id的方法汇总，php生成id汇总
php生成唯一数字id的方法汇总，php生成id汇总
关于生成唯一数字ID的问题，是不是需要使用rand生成一个随机数，然后去数据库查询是否有这个数呢？感觉这样的话有点费时间，有没有其他方法呢？
当然不是，其实有两种方法可以解决。
1. 如果你只用php而不用数据库的话，那时间戳+随机数是最好的方法，且不重复；
2. 如果需要使用数据库，即你还需要给这个id关联一些其他的数据。那就给MySQL数据库中的表的id一个AUTO_INCREMENT（自增）属性，每次插入一条数据时，id自动+1，然后使用mysql_insert_id()或LAST_INSERT_ID()返回这个自增后的id。
当然，这个问题已经有现成的解决方法了，使用php uuid扩展就能完美解决这个问题，这个扩展能生成唯一的完全数字签名。。
如果你不使用composer请参考https://github.com/lootils/uuid，
如果你的项目是基于composer搭建的，那么请参考https://github.com/ramsey/uuid
具体的源码我就不搬运了，小伙伴们自己取下来就可以直接使用了
PHP生成唯一标识符代码示例：
< ?
//生成唯一标识符
//sha1()函数， "安全散列算法（SHA1）"
function create_unique() {
$data = $_SERVER['HTTP_USER_AGENT'] . $_SERVER['REMOTE_ADDR']
.time() . rand();
return sha1($data);
//return md5(time().$data);
//return $data;
}
?>
PHP生成唯一标识符函数描述及例子
< ? $newhash = create_unique(); echo $newhash; ?>
再给大家分享一个
/*
* 信号量(Semaphore)。
* 这是一个包装类，用于解决不同平台下对“信号量”的不同实现方式。
* 目前这个类只是象征性的，在 Windows 平台下实际是空跑（并没有真的实现互斥）。
*/
class SemWrapper
{
private $hasSemSupport;
private $sem;
const SEM_KEY = 1;
public function __construct()
{
$this->hasSemSupport = function_exists( 'sem_get' );
if ( $this->hasSemSupport ) {
$this->sem = sem_get( self::SEM_KEY );
}
}
public function acquire() {
if ( $this->hasSemSupport ) {
return sem_acquire( $this->sem );
}
return true;
}
public function release() {
if ( $this->hasSemSupport ) {
return sem_release( $this->sem );
}
return true;
}
}
/*
* 顺序号发生器。
*/
class SeqGenerator
{
const SHM_KEY = 1;
/**
* 对顺序号发生器进行初始化。
* 仅在服务器启动后的第一次调用有效，此后再调用此方法没有实际作用。
* @param int $start 产生顺序号的起始值。
* @return boolean 返回 true 表示成功。
*/
static public function init( $start = 1 )
{
// 通过信号量实现互斥，避免对共享内存的访问冲突
$sw = new SemWrapper;
if ( ! $sw->acquire() ) {
return false;
}
// 打开共享内存
$shm_id = shmop_open( self::SHM_KEY, 'n', 0644, 4 );
if ( empty($shm_id) ) {
// 因使用了 'n' 模式，如果无法打开共享内存，可以认为该共享内存已经创建，无需再次初始化
$sw->release();
return true;
}
// 在共享内存中写入初始值
$size = shmop_write( $shm_id, pack( 'L', $start ), 0 );
if ( $size != 4 ) {
shmop_close( $shm_id );
$sw->release();
return false;
}
// 关闭共享内存，释放信号量
shmop_close( $shm_id );
$sw->release();
return true;
}
/**
* 产生下一个顺序号。
* @return int 产生的顺序号
*/
static public function next()
{
// 通过信号量实现互斥，避免对共享内存的访问冲突
$sw = new SemWrapper;
if ( ! $sw->acquire() ) {
return 0;
}
// 打开共享内存
$shm_id = shmop_open( self::SHM_KEY, 'w', 0, 0 );
if ( empty($shm_id) ) {
$sw->release();
return 0;
}
// 从共享内存中读出顺序号
$data = shmop_read( $shm_id, 0, 4 );
if ( empty($data) ) {
$sw->release();
return 0;
}
$arr = unpack( 'L', $data );
$seq = $arr[1];
// 把下一个顺序号写入共享内存
$size = shmop_write( $shm_id, pack( 'L', $seq + 1 ), 0 );
if ( $size != 4 ) {
$sw->release();
return 0;
}
// 关闭共享内存，释放信号量
shmop_close( $shm_id );
$sw->release();
return $seq;
}
}
$a = SeqGenerator::init( time() );
var_dump($a);
for ( $i=0; $i < 10; $i++ ) {
$seq = SeqGenerator::next();
var_dump($seq);
}好了，今天就先到这里吧，希望对大家学习PHP能够有所帮助
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