【移動應用開發(fā)技術(shù)】怎么在Android中持久化保存cookie

【移動應用開發(fā)技術(shù)】怎么在Android中持久化保存cookie

本篇文章為大家展示了怎么在Android中持久化保存cookie，內(nèi)容簡明扼要并且容易理解，絕對能使你眼前一亮，通過這篇文章的詳細介紹希望你能有所收獲。什么是Cookies？Cookies是一些小文件，它們被創(chuàng)建在客戶端的系統(tǒng)里，或者被創(chuàng)建在客戶端瀏覽器的內(nèi)存中（如果是臨時性的話）。用它可以實現(xiàn)狀態(tài)管理的功能。我們可以存儲一些少量信息到可以短的系統(tǒng)上，以便在需要的時候使用。最有趣的事情是，它是對用戶透明的。在你的web應用程序中，你可以到處使用它，它極其得簡單。Cookies是以文本形式存儲的。如果一個web應用程序使用cookies，那么服務器負責發(fā)送cookies，客戶端瀏覽器將存儲它。瀏覽器在下次請求頁面的時候，會返回cookies給服務器。最常用的例子是，使用一個cookie來存儲用戶信息，用戶的喜好，“記住密碼”操作等。Cookies有許多優(yōu)點，當然也有許多缺點。我將在接下來講述。Cookies是如何創(chuàng)建的？當一個客戶端向服務器發(fā)出請求，服務器發(fā)送cookies給客戶端。而相同的cookies可以被后續(xù)的請求使用。例如，如果將SessionID作為cookies存儲。當一個客戶端首次向web服務器請求頁面，服務器生成SessionID，并將其作為cookies發(fā)送往客戶端?，F(xiàn)在，所有來自相同客戶端的后續(xù)請求，它將使用來自cookies的SessionID，就像下面這幅圖片展示的那樣。瀏覽器和web服務器以交換cookies信息來作為響應。對不同的站點，瀏覽器會維護不同的cookies。如果一個頁面需要cookies中的信息，當某個URL被“點擊”，首先瀏覽器將搜索本地系統(tǒng)的cookies的信息，然后才轉(zhuǎn)向服務器來獲得信息。Cookies的優(yōu)勢下面是使用cookies的主要優(yōu)勢：(1)

實現(xiàn)和使用都是非常簡單的(2)

由瀏覽器來負責維護發(fā)送過來的數(shù)據(jù)（cookies內(nèi)容）(3)

對來自多個站點的cookies來講，瀏覽器自動管理它們Cookies的劣勢下面是cookies的主要劣勢：(1)

它以簡單的文本格式來存儲數(shù)據(jù)，所以它一點也不安全(2)

對于cookies數(shù)據(jù)，有大小限制（4kB）(3)

Cookies最大數(shù)目也有限制。主流瀏覽器提供將cookies的個數(shù)限制在20條。如果新cookies到來，那么老的將被刪除。有些瀏覽器能支持到300條的cookies數(shù)。(4)

我們需要配置瀏覽器，cookies將不能工作在瀏覽器配置的高安全級別環(huán)境下。什么是持久化的和非持久化的Cookies我們可以將cookies分成兩類：(1)

持久化的cookies(2)

非持久化的cookies持久化的cookies：這可以被稱為永久性的cookies，它被存儲在客戶端的硬盤內(nèi)，直到它們失效。持久化的cookies應該被設置一個失效時間。有時，它們會一直存在直到用戶刪除它們。持久化的cookies通常被用來為某個系統(tǒng)收集一個用戶的標識信息。非持久化cookies：也可以被稱之為臨時性的cookies。如果沒有定義失效時間，那么cookie將會被存儲在瀏覽器的內(nèi)存中。我上面展示的例子就是一個非持久的cookies。修改一個持久化的cookies與一個非持久化的cookies并沒有什么不同。它們唯一的區(qū)別是——持久化的cookies有一個失效時間的設置。Cookie持久化HttpClient可以和任意物理表示的實現(xiàn)了CookieStore接口的持久化cookie存儲一起使用。默認的CookieStore實現(xiàn)稱為BasicClientCookie，這是憑借java.util.ArrayList的一個簡單實現(xiàn)。在BasicClientCookie對象中存儲的cookie當容器對象被垃圾回收機制回收時會丟失。如果需要，用戶可以提供更復雜的實現(xiàn)。下載著重介紹在安卓中如何利用httpclient來實現(xiàn)對cookie的持久化操作：一、請求網(wǎng)絡獲取cookie先看一下下面的代碼：DefaultHttpClient

httpclient

=

new

DefaultHttpClient();

HttpGet

httpget

=

new

HttpGet("");

HttpResponse

response

=

httpclient.execute(httpget);

HttpEntity

entity

=

response.getEntity();

List<Cookie>

cookies

=

httpclient.getCookieStore().getCookies();Post模擬登錄HttpPost

httpPost

=

new

HttpPost(url);

List<NameValuePair>

formparams

=

new

ArrayList<NameValuePair>();

formparams.add(new

BasicNameValuePair("id",

userid));

formparams.add(new

BasicNameValuePair("passwd",

passwd));

UrlEncodedFormEntity

entity;

try

{

entity

=

new

UrlEncodedFormEntity(formparams,

mobileSMTHEncoding);

}

catch

(UnsupportedEncodingException

e1)

{

return

3;

}

httpPost.setEntity(entity);

httpPost.setHeader("User-Agent",

userAgent);

HttpResponse

response

=

httpClient.execute(httpPost);二、保存cookie保存cookie有兩種方式一種是數(shù)據(jù)庫，另一種是SharedPreferences，其中/article/140423.htm是使用數(shù)據(jù)庫來保存的，這里我是使用SharedPreferences保存。

package

com.smthbest.smth.util;

import

java.util.Locale;

import

android.content.Context;

import

android.content.SharedPreferences;

import

android.text.TextUtils;

import

android.util.Log;

import

org.apache.http.client.CookieStore;

import

org.apache.http.cookie.Cookie;

import

java.io.ByteArrayInputStream;

import

java.io.ByteArrayOutputStream;

import

java.io.ObjectInputStream;

import

java.io.ObjectOutputStream;

import

java.util.ArrayList;

import

java.util.Date;

import

java.util.List;

import

java.util.Locale;

import

java.util.concurrent.ConcurrentHashMap;

ic

class

PersistentCookieStore

implements

CookieStore

{

private

static

final

String

LOG_TAG

=

"PersistentCookieStore";

private

static

final

String

COOKIE_PREFS

=

"CookiePrefsFile";

private

static

final

String

COOKIE_NAME_STORE

=

"names";

private

static

final

String

COOKIE_NAME_PREFIX

=

"cookie_";

private

boolean

omitNonPersistentCookies

=

false;

private

final

ConcurrentHashMap<String,

Cookie>

cookies;

private

final

SharedPreferences

cookiePrefs;

/**

*

Construct

a

persistent

cookie

store.

*

*

@param

context

Context

to

attach

cookie

store

to

*/

public

PersistentCookieStore(Context

context)

{

cookiePrefs

=

context.getSharedPreferences(COOKIE_PREFS,

0);

cookies

=

new

ConcurrentHashMap<String,

Cookie>();

//

Load

any

previously

stored

cookies

into

the

store

String

storedCookieNames

=

cookiePrefs.getString(COOKIE_NAME_STORE,

null);

if

(storedCookieNames

!=

null)

{

String[]

cookieNames

=

TextUtils.split(storedCookieNames,

",");

for

(String

name

:

cookieNames)

{

String

encodedCookie

=

cookiePrefs.getString(COOKIE_NAME_PREFIX

+

name,

null);

if

(encodedCookie

!=

null)

{

Cookie

decodedCookie

=

decodeCookie(encodedCookie);

if

(decodedCookie

!=

null)

{

cookies.put(name,

decodedCookie);

}

}

}

//

Clear

out

expired

cookies

clearExpired(new

Date());

}

}

@Override

public

void

addCookie(Cookie

cookie)

{

if

(omitNonPersistentCookies

&&

!cookie.isPersistent())

return;

String

name

=

cookie.getName()

+

cookie.getDomain();

//

Save

cookie

into

local

store,

or

remove

if

expired

if

(!cookie.isExpired(new

Date()))

{

cookies.put(name,

cookie);

}

else

{

cookies.remove(name);

}

//

Save

cookie

into

persistent

store

SharedPreferences.Editor

prefsWriter

=

cookiePrefs.edit();

prefsWriter.putString(COOKIE_NAME_STORE,

TextUtils.join(",",

cookies.keySet()));

prefsWriter.putString(COOKIE_NAME_PREFIX

+

name,

encodeCookie(new

SerializableCookie(cookie)));

prefsWmit();

}

@Override

public

void

clear()

{

//

Clear

cookies

from

persistent

store

SharedPreferences.Editor

prefsWriter

=

cookiePrefs.edit();

for

(String

name

:

cookies.keySet())

{

prefsWriter.remove(COOKIE_NAME_PREFIX

+

name);

}

prefsWriter.remove(COOKIE_NAME_STORE);

prefsWmit();

//

Clear

cookies

from

local

store

cookies.clear();

}

@Override

public

boolean

clearExpired(Date

date)

{

boolean

clearedAny

=

false;

SharedPreferences.Editor

prefsWriter

=

cookiePrefs.edit();

for

(ConcurrentHashMap.Entry<String,

Cookie>

entry

:

cookies.entrySet())

{

String

name

=

entry.getKey();

Cookie

cookie

=

entry.getValue();

if

(cookie.isExpired(date))

{

//

Clear

cookies

from

local

store

cookies.remove(name);

//

Clear

cookies

from

persistent

store

prefsWriter.remove(COOKIE_NAME_PREFIX

+

name);

//

We've

cleared

at

least

one

clearedAny

=

true;

}

}

//

Update

names

in

persistent

store

if

(clearedAny)

{

prefsWriter.putString(COOKIE_NAME_STORE,

TextUtils.join(",",

cookies.keySet()));

}

prefsWmit();

return

clearedAny;

}

@Override

public

List<Cookie>

getCookies()

{

return

new

ArrayList<Cookie>(cookies.values());

}

/**

*

Will

make

PersistentCookieStore

instance

ignore

Cookies,

which

are

non-persistent

by

*

signature

(`Cookie.isPersistent`)

*

*

@param

omitNonPersistentCookies

true

if

non-persistent

cookies

should

be

omited

*/

public

void

setOmitNonPersistentCookies(boolean

omitNonPersistentCookies)

{

this.omitNonPersistentCookies

=

omitNonPersistentCookies;

}

/**

*

Non-standard

helper

method,

to

delete

cookie

*

*

@param

cookie

cookie

to

be

removed

*/

public

void

deleteCookie(Cookie

cookie)

{

String

name

=

cookie.getName();

cookies.remove(name);

SharedPreferences.Editor

prefsWriter

=

cookiePrefs.edit();

prefsWriter.remove(COOKIE_NAME_PREFIX

+

name);

prefsWmit();

}

/**

*

Serializes

Cookie

object

into

String

*

*

@param

cookie

cookie

to

be

encoded,

can

be

null

*

@return

cookie

encoded

as

String

*/

protected

String

encodeCookie(SerializableCookie

cookie)

{

if

(cookie

==

null)

return

null;

ByteArrayOutputStream

os

=

new

ByteArrayOutputStream();

try

{

ObjectOutputStream

outputStream

=

new

ObjectOutputStream(os);

outputStream.writeObject(cookie);

}

catch

(Exception

e)

{

return

null;

}

return

byteArrayToHexString(os.toByteArray());

}

/**

*

Returns

cookie

decoded

from

cookie

string

*

*

@param

cookieString

string

of

cookie

as

returned

from

http

request

*

@return

decoded

cookie

or

null

if

exception

occured

*/

protected

Cookie

decodeCookie(String

cookieString)

{

byte[]

bytes

=

hexStringToByteArray(cookieString);

ByteArrayInputStream

byteArrayInputStream

=

new

ByteArrayInputStream(bytes);

Cookie

cookie

=

null;

try

{

ObjectInputStream

objectInputStream

=

new

ObjectInputStream(byteArrayInputStream);

cookie

=

((SerializableCookie)

objectInputStream.readObject()).getCookie();

}

catch

(Exception

exception)

{

Log.d(LOG_TAG,

"decodeCookie

failed",

exception);

}

return

cookie;

}

/**

*

Using

some

super

basic

byte

array

<->

hex

conversions

so

we

don't

have

to

rely

on

any

*

large

Base64

libraries.

Can

be

overridden

if

you

like!

*

*

@param

bytes

byte

array

to

be

converted

*

@return

string

containing

hex

values

*/

protected

String

byteArrayToHexString(byte[]

bytes)

{

StringBuilder

sb

=

new

StringBuilder(bytes.length

*

2);

for

(byte

element

:

bytes)

{

int

v

=

element

&

0xff;

if

(v

<

16)

{

sb.append('0');

}

sb.append(Integer.toHexString(v));

}

return

sb.toString().toUpperCase(Locale.US);

}

/**

*

Converts

hex

values

from

strings

to

byte

arra

*

*

@param

hexString

string

of

h