go web cookie和session

cookie是存儲在瀏覽器端,session是服務器端

cookie是有時間限制的,分會話cookie和持久cookie,如果不設置時間,那周期就是創建到瀏覽器關閉為止.這種是會話cookie,一般保存在內存中

如果設置了過期時間,瀏覽器就會把cookie保存在硬盤中.

Session是在服務端保存的一個數據結構，用來跟蹤用戶的狀態，這個數據可以保存在集群、數據庫、文件中；
Cookie是客戶端保存用戶信息的一種機制，用來記錄用戶的一些信息，也是實現Session的一種方式。

在go語言中的cookie結構體

type Cookie struct {
	Name       string
	Value      string
	Path       string
	Domain     string
	Expires    time.Time
	RawExpires string

// MaxAge=0 means no 'Max-Age' attribute specified.
// MaxAge<0 means delete cookie now, equivalently 'Max-Age: 0'
// MaxAge>0 means Max-Age attribute present and given in seconds
	MaxAge   int
	Secure   bool
	HttpOnly bool
	Raw      string
	Unparsed []string // Raw text of unparsed attribute-value pairs
}

全局的session管理器

type Manager struct {
	cookieName  string     // private cookiename
	lock        sync.Mutex // protects session
	provider    Provider
	maxLifeTime int64
}

func NewManager(provideName, cookieName string, maxLifeTime int64) (*Manager, error) {
	provider, ok := provides[provideName]
	if !ok {
		return nil, fmt.Errorf("session: unknown provide %q (forgotten import?)", provideName)
	}
	return &Manager{provider: provider, cookieName: cookieName, maxLifeTime: maxLifeTime}, nil
}

package memory

import (
	"container/list"
	"github.com/astaxie/session"
	"sync"
	"time"
)
//內存存儲的session機制
var pder = &Provider{list: list.New()}

type SessionStore struct {
	sid          string                      //session id唯一標示
	timeAccessed time.Time                   //最后訪問時間
	value        map[interface{}]interface{} //session里面存儲的值
}

func (st *SessionStore) Set(key, value interface{}) error {
	st.value[key] = value
	pder.SessionUpdate(st.sid)
	return nil
}

func (st *SessionStore) Get(key interface{}) interface{} {
	pder.SessionUpdate(st.sid)
	if v, ok := st.value[key]; ok {
		return v
	} else {
		return nil
	}
}

func (st *SessionStore) Delete(key interface{}) error {
	delete(st.value, key)
	pder.SessionUpdate(st.sid)
	return nil
}

func (st *SessionStore) SessionID() string {
	return st.sid
}

type Provider struct {
	lock     sync.Mutex               //用來鎖
	sessions map[string]*list.Element //用來存儲在內存
	list     *list.List               //用來做gc
}

func (pder *Provider) SessionInit(sid string) (session.Session, error) {
	pder.lock.Lock()
	defer pder.lock.Unlock()
	v := make(map[interface{}]interface{}, 0)
	newsess := &SessionStore{sid: sid, timeAccessed: time.Now(), value: v}
	element := pder.list.PushBack(newsess)
	pder.sessions[sid] = element
	return newsess, nil
}

func (pder *Provider) SessionRead(sid string) (session.Session, error) {
	if element, ok := pder.sessions[sid]; ok {
		return element.Value.(*SessionStore), nil
	} else {
		sess, err := pder.SessionInit(sid)
		return sess, err
	}
	return nil, nil
}

func (pder *Provider) SessionDestroy(sid string) error {
	if element, ok := pder.sessions[sid]; ok {
		delete(pder.sessions, sid)
		pder.list.Remove(element)
		return nil
	}
	return nil
}

func (pder *Provider) SessionGC(maxlifetime int64) {
	pder.lock.Lock()
	defer pder.lock.Unlock()

	for {
		element := pder.list.Back()
		if element == nil {
			break
		}
		if (element.Value.(*SessionStore).timeAccessed.Unix() + maxlifetime) < time.Now().Unix() {
			pder.list.Remove(element)
			delete(pder.sessions, element.Value.(*SessionStore).sid)
		} else {
			break
		}
	}
}

func (pder *Provider) SessionUpdate(sid string) error {
	pder.lock.Lock()
	defer pder.lock.Unlock()
	if element, ok := pder.sessions[sid]; ok {
		element.Value.(*SessionStore).timeAccessed = time.Now()
		pder.list.MoveToFront(element)
		return nil
	}
	return nil
}

func init() {         //自動運行init函數
	pder.sessions = make(map[string]*list.Element, 0)
	session.Register("memory", pder)
}