Android XMPP通讯自定义Packet&Provider
摘要
在xmpp通信过程中,asmack中提供的Packet组件是IQ,Message,Presence三种: IQ用于查询 Message用于消息传递 Presence用于状态交互 他们都是Packet的子类,实质是用于将消息封装成响应的xml格式来进行数据交换,都有着良好的可扩展性。
简介
我们以开源项目androidpn为例:
androidpn (Android Push Notification)是一个基于XMPP协议的java开源Android push notification实现。它包含了完整的客户端和服务器端。
androidpn包括Server端和Client端,项目名称是androidpn-server和androidpn-client。
事实上,androidpn-server可以支持app运行于iOS,UWP,Windows,Linux等平台,不仅限于android,因此,希望项目的名称改为XPN(Xmpp Push Notification)似乎更加符合其实际场景,我们以后涉及到Android Push Notification统称为XPN。
XNP目前状态
项目自2014年1月就已经停止更新了,此外,asmack项目也停止更新了,作者建议使用openfire官方的smack4.0,不过这样的话引入的jar会特别多,特别大。当然,我们下载到了asmack8.10.0比较新的稳定版本,可以完全用于学习和扩展。
项目相关下载站点
asmack-github.com- asmack项目地址
asmack-asmack.freakempire.de - asmack镜像地址
androidpn(XPN)-github.com - androidpn下载地址
一.关于Packet数据包
Packet是IQ,Message,Presence的父类,用于实现消息组件类型。
消息语义学message
message是一种基本推送消息方法,它不要求响应。主要用于IM、groupChat、alert和notification之类的应用中。
主要 属性如下:
type属性,它主要有5种类型:
normal:类似于email,主要特点是不要求响应;
chat:类似于qq里的好友即时聊天,主要特点是实时通讯;
groupchat:类似于聊天室里的群聊;
headline:用于发送alert和notification;
error:如果发送message出错,发现错误的实体会用这个类别来通知发送者出错了;
to属性:标识消息的接收方。
from属性:指发送方的名字或标示。为防止地址外泄,这个地址通常由发送者的server填写,而不是发送者。
载荷(payload):例如body,subject
<message to="lily@jabber.org/contact" type="chat" > <body> 你好,在忙吗</body> </message>
出席信息语义学presence
presence用来表明用户的状态,如:online、away、dnd(请勿打扰)等。当改变自己的状态时,就会在stream的上下文中插入一个Presence元素,来表明自身的状态。要想接受presence消息,必须经过一个叫做presence subscription的授权过程。
属性:
type属性,非必须。有以下类别
subscribe:订阅其他用户的状态
probe:请求获取其他用户的状态
unavailable:不可用,离线(offline)状态
to属性:标识消息的接收方。
from属性:指发送方的名字或标示。
载荷(payload):
show:
chat:聊天中
away:暂时离开
xa:eXtend Away,长时间离开
dnd:勿打扰
status:格式自由,可阅读的文本。也叫做rich presence或者extended presence,常用来表示用户当前心情,活动,听的歌曲,看的视频,所在的聊天室,访问的网页,玩的游戏等等。
priority:范围-128~127。高优先级的resource能接受发送到bare JID的消息,低优先级的resource不能。优先级为
<presence from="alice@wonderland.lit/pda">
<show>xa</show>
<status>down the rabbit hole!</status>
</presence>
IQ语义学
一种请求/响应机制,从一个实体从发送请求,另外一个实体接受请求,并进行响应。例如,client在stream的上下文中插入一个元素,向Server请求得到自己的好友列表,Server返回一个,里面是请求的结果。
主要的属性是type。包括:
Get :获取当前域值。类似于http get方法。
Set :设置或替换get查询的值。类似于http put方法。
Result :说明成功的响应了先前的查询。类似于http状态码200。
Error: 查询和响应中出现的错误。
<iq from="alice@wonderland.lit/pda"
id="rr82a1z7"
to="alice@wonderland.lit"
type="get">
<query xmlns="jabber:iq:roster"/>
</iq>
二.自定义Packet
由于服务器和客户端使用的Packet不同,但是他们交互的数据格式都是xml,因此,这个过程我们理解xml实现过程即可。
1.定义Packet封装对象
由于asmack标签解析的限制,我们不能自定义解析,除非修改源码,这里出于简单,这里只能继承现有标签之一。
我么按照项目代码NotificationIQ为例,这里没有继承Packet,而是继承了IQ
import org.jivesoftware.smack.packet.IQ; /** * This class represents a notifcatin IQ packet. * * @author Sehwan Noh (devnoh@gmail.com) */ public class NotificationIQ extends IQ { private String id; private String apiKey; private String title; private String message; private String uri; public NotificationIQ() { } @Override public String getChildElementXML() { StringBuilder buf = new StringBuilder(); buf.append("<").append("notification").append(" xmlns=\"").append( "androidpn:iq:notification").append("\">"); if (id != null) { buf.append("<id>").append(id).append("</id>"); } buf.append("</").append("notification").append("> "); return buf.toString(); } public String getId() { return id; } public void setId(String id) { this.id = id; } public String getApiKey() { return apiKey; } public void setApiKey(String apiKey) { this.apiKey = apiKey; } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public String getMessage() { return message; } public void setMessage(String message) { this.message = message; } public String getUri() { return uri; } public void setUri(String url) { this.uri = url; } }
其中,getChildElementXml()是IQ的子类,用来拼接成<iq>下的直接点。
public abstract class IQ extends Packet { private Type type = Type.GET; public IQ() { super(); } public IQ(IQ iq) { super(iq); type = iq.getType(); } /** * Returns the type of the IQ packet. * * @return the type of the IQ packet. */ public Type getType() { return type; } /** * Sets the type of the IQ packet. * * @param type the type of the IQ packet. */ public void setType(Type type) { if (type == null) { this.type = Type.GET; } else { this.type = type; } } public String toXML() { StringBuilder buf = new StringBuilder(); buf.append("<iq "); if (getPacketID() != null) { buf.append("id=\"" + getPacketID() + "\" "); } if (getTo() != null) { buf.append("to=\"").append(StringUtils.escapeForXML(getTo())).append("\" "); } if (getFrom() != null) { buf.append("from=\"").append(StringUtils.escapeForXML(getFrom())).append("\" "); } if (type == null) { buf.append("type=\"get\">"); } else { buf.append("type=\"").append(getType()).append("\">"); } // Add the query section if there is one. String queryXML = getChildElementXML(); if (queryXML != null) { buf.append(queryXML); } // Add the error sub-packet, if there is one. XMPPError error = getError(); if (error != null) { buf.append(error.toXML()); } buf.append("</iq>"); return buf.toString(); } /** * Returns the sub-element XML section of the IQ packet, or <tt>null</tt> if there * isn't one. Packet extensions <b>must</b> be included, if any are defined.<p> * * Extensions of this class must override this method. * * @return the child element section of the IQ XML. */ public abstract String getChildElementXML(); /** * Convenience method to create a new empty {@link Type#RESULT IQ.Type.RESULT} * IQ based on a {@link Type#GET IQ.Type.GET} or {@link Type#SET IQ.Type.SET} * IQ. The new packet will be initialized with:<ul> * <li>The sender set to the recipient of the originating IQ. * <li>The recipient set to the sender of the originating IQ. * <li>The type set to {@link Type#RESULT IQ.Type.RESULT}. * <li>The id set to the id of the originating IQ. * <li>No child element of the IQ element. * </ul> * * @param iq the {@link Type#GET IQ.Type.GET} or {@link Type#SET IQ.Type.SET} IQ packet. * @throws IllegalArgumentException if the IQ packet does not have a type of * {@link Type#GET IQ.Type.GET} or {@link Type#SET IQ.Type.SET}. * @return a new {@link Type#RESULT IQ.Type.RESULT} IQ based on the originating IQ. */ public static IQ createResultIQ(final IQ request) { if (!(request.getType() == Type.GET || request.getType() == Type.SET)) { throw new IllegalArgumentException( "IQ must be of type 'set' or 'get'. Original IQ: " + request.toXML()); } final IQ result = new IQ() { public String getChildElementXML() { return null; } }; result.setType(Type.RESULT); result.setPacketID(request.getPacketID()); result.setFrom(request.getTo()); result.setTo(request.getFrom()); return result; } /** * Convenience method to create a new {@link Type#ERROR IQ.Type.ERROR} IQ * based on a {@link Type#GET IQ.Type.GET} or {@link Type#SET IQ.Type.SET} * IQ. The new packet will be initialized with:<ul> * <li>The sender set to the recipient of the originating IQ. * <li>The recipient set to the sender of the originating IQ. * <li>The type set to {@link Type#ERROR IQ.Type.ERROR}. * <li>The id set to the id of the originating IQ. * <li>The child element contained in the associated originating IQ. * <li>The provided {@link XMPPError XMPPError}. * </ul> * * @param iq the {@link Type#GET IQ.Type.GET} or {@link Type#SET IQ.Type.SET} IQ packet. * @param error the error to associate with the created IQ packet. * @throws IllegalArgumentException if the IQ packet does not have a type of * {@link Type#GET IQ.Type.GET} or {@link Type#SET IQ.Type.SET}. * @return a new {@link Type#ERROR IQ.Type.ERROR} IQ based on the originating IQ. */ public static IQ createErrorResponse(final IQ request, final XMPPError error) { if (!(request.getType() == Type.GET || request.getType() == Type.SET)) { throw new IllegalArgumentException( "IQ must be of type 'set' or 'get'. Original IQ: " + request.toXML()); } final IQ result = new IQ() { public String getChildElementXML() { return request.getChildElementXML(); } }; result.setType(Type.ERROR); result.setPacketID(request.getPacketID()); result.setFrom(request.getTo()); result.setTo(request.getFrom()); result.setError(error); return result; } /** * A class to represent the type of the IQ packet. The types are: * * <ul> * <li>IQ.Type.GET * <li>IQ.Type.SET * <li>IQ.Type.RESULT * <li>IQ.Type.ERROR * </ul> */ public static class Type { public static final Type GET = new Type("get"); public static final Type SET = new Type("set"); public static final Type RESULT = new Type("result"); public static final Type ERROR = new Type("error"); /** * Converts a String into the corresponding types. Valid String values * that can be converted to types are: "get", "set", "result", and "error". * * @param type the String value to covert. * @return the corresponding Type. */ public static Type fromString(String type) { if (type == null) { return null; } type = type.toLowerCase(); if (GET.toString().equals(type)) { return GET; } else if (SET.toString().equals(type)) { return SET; } else if (ERROR.toString().equals(type)) { return ERROR; } else if (RESULT.toString().equals(type)) { return RESULT; } else { return null; } } private String value; private Type(String value) { this.value = value; } public String toString() { return value; } } }
最终可生成如下结构的数据
<iq from=""> <nofitication xlns=""> <iq>
我们在项目中的使用很简单
xmppManager.getConnection().sendPacket(<NotificationIQ>niq)
当然,上面只是实现了object->xml,接下来我们实现xml->data
2.实现IQProvider
先来看看IQProvider源码
public interface IQProvider { /** * Parse the IQ sub-document and create an IQ instance. Each IQ must have a * single child element. At the beginning of the method call, the xml parser * will be positioned at the opening tag of the IQ child element. At the end * of the method call, the parser <b>must</b> be positioned on the closing tag * of the child element. * * @param parser an XML parser. * @return a new IQ instance. * @throws Exception if an error occurs parsing the XML. */ public IQ parseIQ(XmlPullParser parser) throws Exception; }
实现自定义的解析工具
public class NotificationIQProvider implements IQProvider { public NotificationIQProvider() { } @Override public IQ parseIQ(XmlPullParser parser) throws Exception { NotificationIQ notification = new NotificationIQ(); for (boolean done = false; !done;) { int eventType = parser.next(); if (eventType == 2) { if ("id".equals(parser.getName())) { notification.setId(parser.nextText()); } if ("apiKey".equals(parser.getName())) { notification.setApiKey(parser.nextText()); } if ("title".equals(parser.getName())) { notification.setTitle(parser.nextText()); } if ("message".equals(parser.getName())) { notification.setMessage(parser.nextText()); } if ("uri".equals(parser.getName())) { notification.setUri(parser.nextText()); } } else if (eventType == 3 && "notification".equals(parser.getName())) { done = true; } } return notification; } }
项目中使用方法
ProviderManager.getInstance().addIQProvider("notification", "androidpn:iq:notification", new NotificationIQProvider());
在asmack中PacketParserUtils类中会进行如下调用
Object provider = ProviderManager.getInstance().getIQProvider(elementName, namespace); if (provider != null) { if (provider instanceof IQProvider) { iqPacket = ((IQProvider)provider).parseIQ(parser); } else if (provider instanceof Class) { iqPacket = (IQ)PacketParserUtils.parseWithIntrospection(elementName, (Class<?>)provider, parser); } }