Android XMPP自定義Packet&Provider

時間 2019-11-13

標籤 android xmpp 自定義 packet&provider packet provider 欄目 Android 简体版

原文原文鏈接

簡介

咱們以開源項目androidpn爲例：java

androidpn (Android Push Notification)是一個基於XMPP協議的java開源Android push notification實現。它包含了完整的客戶端和服務器端。android

androidpn包括Server端和Client端，項目名稱是androidpn-server和androidpn-client。git

事實上，androidpn-server能夠支持app運行於iOS，UWP，Windows，Linux等平臺，不只限於android，所以，但願項目的名稱改成XPN(Xmpp Push Notification)彷佛更加符合其實際場景，咱們之後涉及到Android Push Notification統稱爲XPN。github

XNP目前狀態api

項目自2014年1月就已經中止更新了，此外，asmack項目也中止更新了，做者建議使用openfire官方的smack4.0，不過這樣的話引入的jar會特別多，特別大。固然，咱們下載到了asmack8.10.0比較新的穩定版本，能夠徹底用於學習和擴展。服務器

項目相關下載站點app

asmack-github.com - asmack項目地址ide

asmack-asmack.freakempire.de - asmack鏡像地址工具

androidpn(XPN)-github.com - androidpn下載地址學習

一.關於Packet數據包

Packet是IQ,Message,Presence的父類，用於實現消息組件類型。

消息語義學message

message是一種基本推送消息方法，它不要求響應。主要用於IM、groupChat、alert和notification之類的應用中。
主要 屬性以下：
    type屬性，它主要有5種類型：
        normal：相似於email，主要特色是不要求響應；
        chat：相似於qq裏的好友即時聊天，主要特色是實時通信；
        groupchat：相似於聊天室裏的羣聊；
        headline：用於發送alert和notification；
        error：若是發送message出錯，發現錯誤的實體會用這個類別來通知發送者出錯了；
to屬性：標識消息的接收方。
from屬性：指發送方的名字或標示。爲防止地址外泄，這個地址一般由發送者的server填寫，而不是發送者。
載荷（payload）：例如body，subject

<message to="lily@jabber.org/contact"  
  type="chat" > 
    <body> 你好，在忙嗎</body> 
</message>

出席信息語義學presence

presence用來代表用戶的狀態，如：online、away、dnd(請勿打擾)等。當改變本身的狀態時，就會在stream的上下文中插入一個Presence元素，來代表自身的狀態。要想接受presence消息，必須通過一個叫作presence subscription的受權過程。 
屬性：
type屬性，非必須。有如下類別
    subscribe：訂閱其餘用戶的狀態
    probe：請求獲取其餘用戶的狀態
    unavailable：不可用，離線（offline）狀態
to屬性：標識消息的接收方。
from屬性：指發送方的名字或標示。
載荷（payload）： 
    show：
    chat：聊天中
    away：暫時離開
    xa：eXtend Away，長時間離開
    dnd：勿打擾
status：格式自由，可閱讀的文本。也叫作rich presence或者extended presence，經常使用來表示用戶當前心情，活動，聽的歌曲，看的視頻，所在的聊天室，訪問的網頁，玩的遊戲等等。
priority：範圍-128~127。高優先級的resource能接受發送到bare JID的消息，低優先級的resource不能。優先級爲

<presence from="alice@wonderland.lit/pda"> 
  <show>xa</show> 
  <status>down the rabbit hole!</status> 
</presence>

IQ語義學

一種請求／響應機制，從一個實體從發送請求，另一個實體接受請求，並進行響應。例如，client在stream的上下文中插入一個元素，向Server請求獲得本身的好友列表，Server返回一個，裏面是請求的結果。 
主要的屬性是type。包括: 
    Get :獲取當前域值。相似於http get方法。
    Set :設置或替換get查詢的值。相似於http put方法。
    Result :說明成功的響應了先前的查詢。相似於http狀態碼200。
    Error: 查詢和響應中出現的錯誤。

<iq from="alice@wonderland.lit/pda"  
    id="rr82a1z7" 
    to="alice@wonderland.lit"  
    type="get"> 
  <query xmlns="jabber:iq:roster"/> 
</iq>

二.自定義Packet

因爲服務器和客戶端使用的Packet不一樣，可是他們交互的數據格式都是xml，所以，這個過程咱們理解xml實現過程便可。

1.定義Packet封裝對象

因爲asmack標籤解析的限制，咱們不能自定義解析，除非修改源碼，這裏出於簡單，這裏只能繼承現有標籤之一。

我麼按照項目代碼NotificationIQ爲例，這裏沒有繼承Packet，而是繼承了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的子類，用來拼接成<iq>下的直接點。

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;
        }
    }
}

最終可生成以下結構的數據

<iq from="">
  <nofitication xlns="">
<iq>

咱們在項目中的使用很簡單

xmppManager.getConnection().sendPacket(<NotificationIQ>niq)

固然，上面只是實現了object->xml，接下來咱們實現xml->data

2.實現IQProvider

先來看看IQProvider源碼

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;
}

實現自定義的解析工具

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;
    }

}

項目中使用方法

ProviderManager.getInstance().addIQProvider("notification",
                            "androidpn:iq:notification",
                            new NotificationIQProvider());

在asmack中PacketParserUtils類中會進行以下調用

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); } }

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