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域名先解析后做网站,如何注册属于自己的网站,wordpress阿里云虚拟机,wordpress数据库被误删参考： Android中Cookie的使用通常来说，Http 请求或者返回，两两之间应该是相互独立的。然而，状态管理机制(the state management mechanism)，可以使客户端(clients) 和服务器(servers)可以通过把这些信息放进一个…

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Android中Cookie的使用

通常来说，Http 请求或者返回，两两之间应该是相互独立的。然而，状态管理机制(the state management mechanism)，可以使客户端(clients) 和服务器(servers)可以通过把这些信息放进一个上下文变量中来实现状态信息的交换，这种方式被称作 Session.这些被用来创建和维护session的状态信息被称作 cookie.

一个Cookie是一个数据片段，它可以被存储在浏览器的缓存中.如果你访问过一个网站，并且再次访问它的时候，这些cookie数据就可以用来识别你是一个“回头客”，说明你之前访问过该网站。Cookies使状态信息的存在成为可能，例如在线的购物车，可以将信息存储起来。一个Cookie可以短期存在，为单个web页面的session维持信息,因此除非你关闭浏览器，否则一个cookie可以长期存在，维持信息一个星期或者一年。

Http 状态的管理是通过java SE中的java.net.CookieHandler这个类来实现的。

一个CookieHandler对象提供了一个回调机制，这些回调机制提供给 Http 状态管理一些规则。而这些规则是在Http protocol Handler 内部实现的。

URLs 使用 HTTP 作为协议，new URL(“http://example.com“)新建一个URLs对象来作为例子，这个会使用HTTP protocol handler.这个 HTTP protocol handler回调 CookieHanlder对象的方法，如果CookieHandler中有设置的话，就可以进行状态管理。

一、CookieHandler


package java.net;import java.util.Map;
import java.util.List;
import java.io.IOException;
import sun.security.util.SecurityConstants;public abstract class CookieHandler {/*** The system-wide cookie handler that will apply cookies to the* request headers and manage cookies from the response headers.** @see setDefault(CookieHandler)* @see getDefault()* * @author Yingxian Wang* @since 1.5*/private static CookieHandler cookieHandler;/*** Gets the system-wide cookie handler.*/public synchronized static CookieHandler getDefault() {SecurityManager sm = System.getSecurityManager();if (sm != null) {sm.checkPermission(SecurityConstants.GET_COOKIEHANDLER_PERMISSION);}return cookieHandler;}/*** Sets (or unsets) the system-wide cookie handler.*/public synchronized static void setDefault(CookieHandler cHandler) {SecurityManager sm = System.getSecurityManager();if (sm != null) {sm.checkPermission(SecurityConstants.SET_COOKIEHANDLER_PERMISSION);}cookieHandler = cHandler;}/*** Gets all the applicable cookies from a cookie cache for the* specified uri in the request header.*/public abstract Map<String, List<String>> get(URI uri, Map<String, List<String>> requestHeaders)throws IOException;/*** Sets all the applicable cookies, examples are response header* fields that are named Set-Cookie2, present in the response* headers into a cookie cache.*/public abstract void put(URI uri, Map<String, List<String>> responseHeaders)throws IOException;
}

CookieHandler是一个抽象类，它有两对相互对应的方法。

第一对：getDefault() 和 setDefault(cookieHandler) 方法 ,
这对方法是静态的。

getDefault() 可以知道当前的handler是否设置了cookieHandler，如果没有，返回值为null
setDefault() 可以设置自己的handler。

第二对：put(uri,responseHeader)和get(uri,requestHeaders)
这对方法是抽象方法

put(uri,responseHeader) 允许你设置所有可用的cookies 到cookies 缓存中
get(uri,requestHeaders) 从cookies缓存中得到所有可用的cookies。
这两个方法分别用在指定的URI的 response 和 request header 中，这两个方法是抽象方法，凡是实现了CookieHandler的，都需要提供内部实现。

二、CookieManager


package java.net;import java.util.Map;
import java.util.List;
import java.util.Collections;
import java.util.Comparator;
import java.io.IOException;
import sun.util.logging.PlatformLogger;/*** CookieManager provides a concrete implementation of {@link CookieHandler},* which separates the storage of cookies from the policy surrounding accepting* and rejecting cookies. A CookieManager is initialized with a {@link CookieStore}* which manages storage, and a {@link CookiePolicy} object, which makes* policy decisions on cookie acceptance/rejection.* *                  use* CookieHandler <------- HttpURLConnection*       ^*       | impl*       |         use* CookieManager -------> CookiePolicy*             |   use*             |--------> HttpCookie*             |              ^*             |              | use*             |   use        |*             |--------> CookieStore*                            ^*                            | impl*                            |*                  Internal in-memory implementation* </pre>* @see CookiePolicy* @author Edward Wang* @since 1.6*/
public class CookieManager extends CookieHandler
{/* ---------------- Fields -------------- */private CookiePolicy policyCallback;private CookieStore cookieJar = null;/* ---------------- Ctors -------------- */public CookieManager() {this(null, null);}/*** Create a new cookie manager with specified cookie store and cookie policy.*/public CookieManager(CookieStore store,CookiePolicy cookiePolicy){// use default cookie policy if not specify onepolicyCallback = (cookiePolicy == null) ? CookiePolicy.ACCEPT_ORIGINAL_SERVER: cookiePolicy;// if not specify CookieStore to use, use default oneif (store == null) {cookieJar = new InMemoryCookieStore();} else {cookieJar = store;}}/* ---------------- Public operations -------------- *//*** To set the cookie policy of this cookie manager.**/public void setCookiePolicy(CookiePolicy cookiePolicy) {if (cookiePolicy != null) policyCallback = cookiePolicy;}/*** To retrieve current cookie store.** @return  the cookie store currently used by cookie manager.*/public CookieStore getCookieStore() {return cookieJar;}public Map<String, List<String>>get(URI uri, Map<String, List<String>> requestHeaders)throws IOException{...}public voidput(URI uri, Map<String, List<String>> responseHeaders)throws IOException{...}}

1、Default CookieManager

java.net.CookieManger提供了一个构造方法的方式来实现CookieHandler对状态的管理。这种方式对大多数人来说，已经足够了。CookieManger通过policy来划分存储的cookies，通过policy可以实现接收和拒绝cookies。

CookieManger通过java.net.CookieStore和java.net.CookiePolicy参数来进行初始化。

CookieStore 管理cookies的存储

CookiePolicy 用来决定哪些cookies应该接收存储，哪些cookies应该拒绝。

以下的代码用来展示如何创建并且设置一个 system-wide CookieManager (系统通用的CookieManager/默认的CookieManager)

java.net.CookieManager cm = new java.net.CookieManager();
java.net.CookieHandler.setDefault(cm);

第一行代码通过调用默认的CookieManager的构造函数来创建了一个实例

第二行通过调用CookieHandler静态方法setDefault来设置一个system-wide handler.

默认情况下 CookieManager的构造函数，通过默认的 cookie store 和 accept policy.

CookieStore 指明了任何已经接收了的HTTP cookies的存放位置，如果在构造函数中没有指明，CookieManager实例就会使用 in-memory 的CookieStore来实现。这种实现方式，不是持久化的只有在Java虚拟机存活的时候存在。如果用户需要一个持久化的CookieStore必须要进行自己的自定义。

CookieManager使用的默认的cookie policy 是CookiePolicy.ACCEPT_ORIGINAL_SERVER,这种policy只接收对应服务器的cookie.所以，服务器反回的response中Set-Cookie选项中必须要有domain属性，而且这个domain属性的值必须和请求的url中host相匹配。

如果用户需要使用不同的policy的话，必须要实现CookiePolicy接口，然后通过构造方法传递进去，或者通过一个已经创建的CookieManager的setCookiePolicy(cookiePolicy)方法。

2、Custom CookieManager

CookieManager 有两个方面可以进行自定义，CookiePolicy 和 CookieStore

2.1 CookiePolicy

为了使用方便，CooliePolicy定义了一下几个预定义的规则用来接收cookies：

CookiePolicy.ACCEPT_ORIGINAL_SERVER 只接收来自对应Server的cookies.
CookiePolicy.ACCEPT_ALL 接收所有Cookies.
CookiePolicy.ACCEPT_NONE 不接收Cookies.

你也可以通过实现implementing这个shouldAccept方法来定义自己接收Cookie的规则。然后通过CookieManager的多参数构造函数将自定义的CookiePolicy传递进去，或者通过调用setCookiePolicy(cookiePolicy)方法来改变已经存在的cookie Manager.

以下就是一个拒绝接收domain在黑名单中列表中的例子，这个需要在CookiePolicy.ACCEPT_ORIGINAL_SERVER之前调用。

import java.net.*;public class BlacklistCookiePolicy implements CookiePolicy {String[] blacklist;public BlacklistCookiePolicy(String[] list) {blacklist = list;}public boolean shouldAccept(URI uri, HttpCookie cookie)  {String host;try {host =  InetAddress.getByName(uri.getHost()).getCanonicalHostName();} catch (UnknownHostException e) {host = uri.getHost();}for (int i = 0; i<blacklist.length; i++) {if (HttpCookie.domainMatches(blacklist[i], host)) {return false;}}return CookiePolicy.ACCEPT_ORIGINAL_SERVER.shouldAccept(uri, cookie);}
}

当你创建一个 BlacklistCookiePolicy 的实例，你可以传递一个 String array 用来表示一些你不想接受cookie 的domain.

然后你将这个BlacklistCookiePolicy的实例作为CookieManager的cookie policy 设置进去，举例来说：

String[] list = new String[]{ ".example.com" };
CookieManager cm = new CookieManager(null, new BlacklistCookiePolicy(list));
CookieHandler.setDefault(cm);

以上的示例代码就不会接收以下hosts的cookie：

host.example.com 
domain.example.com

然而，示例代码会接收来自以下hosts的cookie:

example.com 
example.org 
myhost.example.org

2.2 CookieStore

CookieStore作为一个接口，它表示了一个用来存储cookies的地方。

在每一次的Http的Response中CookieManager都会把这些cookies添加到CookieStore中.

在每一次的Http的Request时，CookieManager都会从CookieStore中获取cookies.

你可以通过 implements CookieStore接口来实现自己的CookieStore，然后在CookieManger创建的时候，将自己的CookieStore传递进去，不能在CookieManger已经被创建之后，来设置 CookieStore。但是，你可以通过调用CookieManager.getCookieStore()方法获取cookie Store的引用。这种实现CookieStore接口的做法非常实用，因为这个可以你可以借用 Java SE 提供的默认的内存中的CookieStore的实现，然后自己完善CookieStore的功能。

举例来说，你或许想创建一个持久的 cookie store ，能够在Java虚拟机重启后依然生效的cookie store。你的实现方式，可能如下所示：

1、任何之前存储的cookies都可以被读取进来.
2、在运行环境(Runtime)期间，cookies 存储和获取都是经过内存.
3、在程序退出之前，cookies 会被写出进行持久化操作。

以下这些是一个实现上述功能的不完整的例子。这个例子可以告诉你怎样利用java se中的默认的内存中的cookie store，并且告诉你该怎么扩展他的功能。

import java.net.*;
import java.util.*;public class PersistentCookieStore implements CookieStore, Runnable {CookieStore store;public PersistentCookieStore() {// get the default in memory cookie storestore = new CookieManager().getCookieStore();// todo: read in cookies from persistant storage// and add them store// add a shutdown hook to write out the in memory cookiesRuntime.getRuntime().addShutdownHook(new Thread(this)); }public void run() {// todo: write cookies in store to persistent storage}public void add(URI uri, HttpCookie cookie) {store.add(uri, cookie);}public List<HttpCookie> get(URI uri) {return store.get(uri);}public List<HttpCookie> getCookies() {return store.getCookies();}public List<URI> getURIs() {return store.getURIs();}public boolean remove(URI uri, HttpCookie cookie) {return store.remove(uri, cookie);}public boolean removeAll()  {return store.removeAll();}
}

CookiePolicy ：管理cookies的接受还是拒绝


package java.net;/*** CookiePolicy implementations decide which cookies should be accepted* and which should be rejected. Three pre-defined policy implementations* are provided, namely ACCEPT_ALL, ACCEPT_NONE and ACCEPT_ORIGINAL_SERVER.** <p>See RFC 2965 sec. 3.3 & 7 for more detail.** @author Edward Wang* @since 1.6*/
public interface CookiePolicy {/*** One pre-defined policy which accepts all cookies.*/public static final CookiePolicy ACCEPT_ALL = new CookiePolicy(){public boolean shouldAccept(URI uri, HttpCookie cookie) {return true;}};/*** One pre-defined policy which accepts no cookies.*/public static final CookiePolicy ACCEPT_NONE = new CookiePolicy(){public boolean shouldAccept(URI uri, HttpCookie cookie) {return false;}};/*** One pre-defined policy which only accepts cookies from original server.*/public static final CookiePolicy ACCEPT_ORIGINAL_SERVER  = new CookiePolicy(){public boolean shouldAccept(URI uri, HttpCookie cookie) {return HttpCookie.domainMatches(cookie.getDomain(), uri.getHost());}};/*** Will be called to see whether or not this cookie should be accepted.** @param uri       the URI to consult accept policy with* @param cookie    the HttpCookie object in question* @return          <tt>true</tt> if this cookie should be accepted;*                  otherwise, <tt>false</tt>*/public boolean shouldAccept(URI uri, HttpCookie cookie);
}

CookieStore ：决定cookies的存储，获取


package java.net;import java.util.List;
import java.util.Map;/*** A CookieStore object represents a storage for cookie. Can store and retrieve* cookies.* * @author Edward Wang* @since 1.6*/
public interface CookieStore {/*** Adds one HTTP cookie to the store. This is called for every* incoming HTTP response.** <p>A cookie to store may or may not be associated with an URI. If it* is not associated with an URI, the cookie's domain and path attribute* will indicate where it comes from. If it is associated with an URI and* its domain and path attribute are not speicifed, given URI will indicate* where this cookie comes from.*/public void add(URI uri, HttpCookie cookie);/*** Retrieve cookies associated with given URI, or whose domain matches the* given URI. Only cookies that have not expired are returned.* This is called for every outgoing HTTP request.** @return          an immutable list of HttpCookie,*                  return empty list if no cookies match the given URI** @throws NullPointerException if <tt>uri</tt> is <tt>null</tt>** @see #add**/public List<HttpCookie> get(URI uri);/*** Get all not-expired cookies in cookie store.** @return          an immutable list of http cookies;*                  return empty list if there's no http cookie in store*/public List<HttpCookie> getCookies();/*** Get all URIs which identify the cookies in this cookie store.** @return          an immutable list of URIs;*                  return empty list if no cookie in this cookie store*                  is associated with an URI*/public List<URI> getURIs();/*** Remove a cookie from store.** @param uri       the uri this cookie associated with.*                  if <tt>null</tt>, the cookie to be removed is not associated*                  with an URI when added; if not <tt>null</tt>, the cookie*                  to be removed is associated with the given URI when added.* @param cookie    the cookie to remove** @return          <tt>true</tt> if this store contained the specified cookie** @throws NullPointerException if <tt>cookie</tt> is <tt>null</tt>*/public boolean remove(URI uri, HttpCookie cookie);/*** Remove all cookies in this cookie store.** @return          <tt>true</tt> if this store changed as a result of the call*/public boolean removeAll();
}