项目中有一个IM模块，是使用了WebSocket来做的，特此记录一下。
WebSocket的框架有很多，了解到OkHttp3也有支持WebSocket，就采用了Okhttp来实现。
一个是不需要再引入多一个WebSocket的第三方库，一个是Okhttp3口碑和稳定性都非常好，而且还一直在更新。
添加依赖
implementation 'com.squareup.okhttp3:okhttp:3.8.1'
实现步骤
-
构建OkHttpClient配置初始化一些参数。
-
使用WebSocket的Url地址连接。
-
设置WebSocket的连接状态回调和消息回调。
-
解析消息json处理业务等。
-
连接成功后，使用WebSocket发送消息
- 配置OkHttpClient
OkHttpClient mClient = new OkHttpClient.Builder()
.readTimeout(3, TimeUnit.SECONDS)//设置读取超时时间
.writeTimeout(3, TimeUnit.SECONDS)//设置写的超时时间
.connectTimeout(3, TimeUnit.SECONDS)//设置连接超时时间
.build();
- 使用Url，构建WebSocket请求（一般是后端接口返回连接的Url地址）
//连接地址
String url = "ws://xxxxx"
//构建一个连接请求对象
Request request = new Request.Builder().get().url(url).build();
-
发起连接，配置回调。
- onOpen()，连接成功
- onMessage(String text)，收到字符串类型的消息，一般我们都是使用这个
- onMessage(ByteString bytes)，收到字节数组类型消息，我这里没有用到
- onClosed()，连接关闭
- onFailure()，连接失败，一般都是在这里发起重连操作
//开始连接
WebSocket websocket = mClient.newWebSocket(request, new WebSocketListener() {
@Override
public void onOpen(WebSocket webSocket, Response response) {
super.onOpen(webSocket, response);
//连接成功...
}
@Override
public void onMessage(WebSocket webSocket, String text) {
super.onMessage(webSocket, text);
//收到消息...（一般是这里处理json）
}
@Override
public void onMessage(WebSocket webSocket, ByteString bytes) {
super.onMessage(webSocket, bytes);
//收到消息...（一般很少这种消息）
}
@Override
public void onClosed(WebSocket webSocket, int code, String reason) {
super.onClosed(webSocket, code, reason);
//连接关闭...
}
@Override
public void onFailure(WebSocket webSocket, Throwable throwable, Response response) {
super.onFailure(webSocket, throwable, response);
//连接失败...
}
});
- 使用WebSocket对象发送消息，msg为消息内容（一般是json，当然你也可以使用其他的，例如xml等），send方法会马上返回发送结果。
//发送消息
boolean isSendSuccess = webSocket.send(msg);
配合RxJava封装
配置RxJava，我们可以为WebSocket增强数据转换，线程切换和重连处理等功能。
实现步骤
- 定义Api调用接口，外部只需要接触Api无无需关心内部实现逻辑。
public interface WebSocketWorker {
/**
* 获取连接，并返回观察对象
*/
Observable<WebSocketInfo> get(String url);
/**
* 设置一个超时时间，在指定时间内如果没有收到消息，会尝试重连
*
* @param timeout 超时时间
* @param timeUnit 超时时间单位
*/
Observable<WebSocketInfo> get(String url, long timeout, TimeUnit timeUnit);
/**
* 发送，url的WebSocket已打开的情况下使用，否则会抛出异常
*
* @param msg 消息，看具体和后端协商的格式，一般为json
*/
Observable<Boolean> send(String url, String msg);
/**
* 发送，同上
*
* @param byteString 信息类型为ByteString
*/
Observable<Boolean> send(String url, ByteString byteString);
/**
* 不关心WebSocket是否连接，直接发送
*/
Observable<Boolean> asyncSend(String url, String msg);
/**
* 同上，只是消息类型为ByteString
*/
Observable<Boolean> asyncSend(String url, ByteString byteString);
/**
* 关闭指定Url的连接
*/
Observable<Boolean> close(String url);
/**
* 马上关闭指定Url的连接
*/
boolean closeNow(String url);
/**
* 关闭当前所有连接
*/
Observable<List<Boolean>> closeAll();
/**
* 马上关闭所有连接
*/
void closeAllNow();
}
- 构建者模式，大量的配置参数，我们先使用一个Builder类保存，再使用build()方法生成RxWebSocket对象。
public class RxWebSocketBuilder {
Context mContext;
/**
* 是否打印Log
*/
boolean mIsPrintLog;
/**
* Log代理对象
*/
Logger.LogDelegate mLogDelegate;
/**
* 支持外部传入OkHttpClient
*/
OkHttpClient mClient;
/**
* 支持SSL
*/
SSLSocketFactory mSslSocketFactory;
X509TrustManager mTrustManager;
/**
* 重连间隔时间
*/
long mReconnectInterval;
/**
* 重连间隔时间的单位
*/
TimeUnit mReconnectIntervalTimeUnit;
public RxWebSocketBuilder(Context context) {
this.mContext = context.getApplicationContext();
}
public RxWebSocketBuilder isPrintLog(boolean isPrintLog) {
this.mIsPrintLog = isPrintLog;
return this;
}
public RxWebSocketBuilder logger(Logger.LogDelegate logDelegate) {
Logger.setDelegate(logDelegate);
return this;
}
public RxWebSocketBuilder client(OkHttpClient client) {
this.mClient = client;
return this;
}
public RxWebSocketBuilder sslSocketFactory(SSLSocketFactory sslSocketFactory, X509TrustManager trustManager) {
this.mSslSocketFactory = sslSocketFactory;
this.mTrustManager = trustManager;
return this;
}
public RxWebSocketBuilder reconnectInterval(long reconnectInterval, TimeUnit reconnectIntervalTimeUnit) {
this.mReconnectInterval = reconnectInterval;
this.mReconnectIntervalTimeUnit = reconnectIntervalTimeUnit;
return this;
}
public RxWebSocket build() {
return new RxWebSocket(this);
}
}
- Api实现类，这里我使用代理模式定义一个代理对象，隔离内部实现，暂时只是简单转调实现，后续需要增加限制逻辑时，在这里加），也方便使用装饰者模式增强逻辑。
public class RxWebSocket implements WebSocketWorker {
private Context mContext;
/**
* 是否打印Log
*/
private boolean mIsPrintLog;
/**
* Log代理对象
*/
private Logger.LogDelegate mLogDelegate;
/**
* 支持外部传入OkHttpClient
*/
private OkHttpClient mClient;
/**
* 支持SSL
*/
private SSLSocketFactory mSslSocketFactory;
private X509TrustManager mTrustManager;
/**
* 重连间隔时间
*/
private long mReconnectInterval;
/**
* 重连间隔时间的单位
*/
private TimeUnit mReconnectIntervalTimeUnit;
/**
* 具体干活的实现类
*/
private WebSocketWorker mWorkerImpl;
private RxWebSocket() {
}
RxWebSocket(RxWebSocketBuilder builder) {
this.mContext = builder.mContext;
this.mIsPrintLog = builder.mIsPrintLog;
this.mLogDelegate = builder.mLogDelegate;
this.mClient = builder.mClient == null ? new OkHttpClient() : builder.mClient;
this.mSslSocketFactory = builder.mSslSocketFactory;
this.mTrustManager = builder.mTrustManager;
this.mReconnectInterval = builder.mReconnectInterval == 0 ? 1 : builder.mReconnectInterval;
this.mReconnectIntervalTimeUnit = builder.mReconnectIntervalTimeUnit == null ? TimeUnit.SECONDS : builder.mReconnectIntervalTimeUnit;
setup();
}
/**
* 开始配置
*/
private void setup() {
this.mWorkerImpl = new WebSocketWorkerImpl(
this.mContext,
this.mIsPrintLog,
this.mLogDelegate,
this.mClient,
this.mSslSocketFactory,
this.mTrustManager,
this.mReconnectInterval,
this.mReconnectIntervalTimeUnit);
}
//...Api都是转调mWorkerImpl，mWorkerImpl是具体的实现类
}
- WebSocketInfo消息实体，RxJava发送消息通知订阅者需要一个实体Model类来保存发送的消息，例如发送的消息字符串，标识是否重连，是否连接成功等。
- 需要缓存的模型需要实现的接口
public interface ICacheTarget<T> {
/**
* 重置方法
*
* @return 重置后的对象
*/
T reset();
}
- 缓存池接口
public interface ICachePool<T extends ICacheTarget<T>> {
/**
* 创建缓存时回调
*/
T onCreateCache();
/**
* 设置缓存对象的最大个数
*/
int onSetupMaxCacheCount();
/**
* 获取一个缓存对象
*
* @param cacheKey 缓存Key，为了应对多个观察者同时获取缓存使用
*/
T obtain(String cacheKey);
/**
* 当获取一个缓存后回调，一般在该回调中重置对象的所有字段
*
* @param cacheTarget 缓存对象
*/
T onObtainCacheAfter(ICacheTarget<T> cacheTarget);
}
- 统一的缓存模型包裹类
public class CacheItem<T> implements Serializable {
private static final long serialVersionUID = -401778630524300400L;
/**
* 缓存的对象
*/
private T cacheTarget;
/**
* 最近使用时间
*/
private long recentlyUsedTime;
public CacheItem(T cacheTarget, long recentlyUsedTime) {
this.cacheTarget = cacheTarget;
this.recentlyUsedTime = recentlyUsedTime;
}
public T getCacheTarget() {
return cacheTarget;
}
public void setCacheTarget(T cacheTarget) {
this.cacheTarget = cacheTarget;
}
public long getRecentlyUsedTime() {
return recentlyUsedTime;
}
public void setRecentlyUsedTime(long recentlyUsedTime) {
this.recentlyUsedTime = recentlyUsedTime;
}
}
- 基础缓存池
public abstract class BaseCachePool<T extends ICacheTarget<T>> implements ICachePool<T>, Comparator<CacheItem<T>> {
/**
* 缓存池
*/
private ConcurrentHashMap<String, LinkedList<CacheItem<T>>> mPool;
public BaseCachePool() {
mPool = new ConcurrentHashMap<>(8);
}
@Override
public T obtain(String cacheKey) {
//缓存链
LinkedList<CacheItem<T>> cacheChain;
//没有缓存过，进行缓存
if (!mPool.containsKey(cacheKey)) {
cacheChain = new LinkedList<>();
} else {
cacheChain = mPool.get(cacheKey);
}
if (cacheChain == null) {
throw new NullPointerException("cacheChain 缓存链创建失败");
}
//未满最大缓存数量，生成一个实例
if (cacheChain.size() < onSetupMaxCacheCount()) {
T cache = onCreateCache();
CacheItem<T> cacheItem = new CacheItem<>(cache, System.currentTimeMillis());
cacheChain.add(cacheItem);
mPool.put(cacheKey, cacheChain);
return cache;
}
//达到最大缓存数量。按最近的使用时间排序，最近使用的放后面，每次取只取最前面（最久没有使用的）
Collections.sort(cacheChain, this);
CacheItem<T> cacheItem = cacheChain.getFirst();
cacheItem.setRecentlyUsedTime(System.currentTimeMillis());
//重置所有属性
T cacheTarget = cacheItem.getCacheTarget();
cacheTarget = onObtainCacheAfter(cacheTarget);
return cacheTarget;
}
@Override
public T onObtainCacheAfter(ICacheTarget<T> cacheTarget) {
//默认调用reset方法进行重置，如果有其他需求，子类再进行复写
return cacheTarget.reset();
}
@Override
public int compare(CacheItem<T> o1, CacheItem<T> o2) {
return Long.compare(o1.getRecentlyUsedTime(), o2.getRecentlyUsedTime());
}
}
- 实现我们的缓存模型
public class WebSocketInfo implements Serializable, ICacheTarget<WebSocketInfo> {
private static final long serialVersionUID = -880481254453932113L;
private WebSocket mWebSocket;
private String mStringMsg;
private ByteString mByteStringMsg;
/**
* 连接成功
*/
private boolean isConnect;
/**
* 重连成功
*/
private boolean isReconnect;
/**
* 准备重连
*/
private boolean isPrepareReconnect;
/**
* 重置
*/
@Override
public WebSocketInfo reset() {
this.mWebSocket = null;
this.mStringMsg = null;
this.mByteStringMsg = null;
this.isConnect = false;
this.isReconnect = false;
this.isPrepareReconnect = false;
return this;
}
//省略get、set方法
}
- 具体实现。
- 将连接WebSocket封装到Observable的订阅回调中。
- 以Map缓存Url和数据源，多个Url共享同一个连接对象。
- 使用share操作符，让多个观察者同时订阅一个数据源。所有订阅者都取消订阅时，再断开连接。
public class WebSocketWorkerImpl implements WebSocketWorker {
private static final String TAG = WebSocketWorkerImpl.class.getName();
/**
* 上下文
*/
private Context mContext;
/**
* 支持外部传入OkHttpClient
*/
private OkHttpClient mClient;
/**
* 重连间隔时间
*/
private long mReconnectInterval;
/**
* 重连间隔时间的单位
*/
private TimeUnit mReconnectIntervalTimeUnit;
/**
* 缓存观察者对象，Url对应一个Observable
*/
private Map<String, Observable<WebSocketInfo>> mObservableCacheMap;
/**
* 缓存Url和对应的WebSocket实例，同一个Url共享一个WebSocket连接
*/
private Map<String, WebSocket> mWebSocketPool;
/**
* WebSocketInfo缓存池
*/
private final WebSocketInfoPool mWebSocketInfoPool;
public WebSocketWorkerImpl(
Context context,
boolean isPrintLog,
Logger.LogDelegate logDelegate,
OkHttpClient client,
SSLSocketFactory sslSocketFactory,
X509TrustManager trustManager,
long reconnectInterval,
TimeUnit reconnectIntervalTimeUnit) {
this.mContext = context;
//配置Logger
Logger.setDelegate(logDelegate);
Logger.setLogPrintEnable(isPrintLog);
this.mClient = client;
//重试时间配置
this.mReconnectInterval = reconnectInterval;
this.mReconnectIntervalTimeUnit = reconnectIntervalTimeUnit;
//配置SSL
if (sslSocketFactory != null && trustManager != null) {
mClient = mClient.newBuilder().sslSocketFactory(sslSocketFactory, trustManager).build();
}
this.mObservableCacheMap = new HashMap<>(16);
this.mWebSocketPool = new HashMap<>(16);
mWebSocketInfoPool = new WebSocketInfoPool();
}
@Override
public Observable<WebSocketInfo> get(String url) {
return getWebSocketInfo(url);
}
@Override
public Observable<WebSocketInfo> get(String url, long timeout, TimeUnit timeUnit) {
return getWebSocketInfo(url, timeout, timeUnit);
}
@Override
public Observable<Boolean> send(String url, String msg) {
return Observable.create(new ObservableOnSubscribe<Boolean>() {
@Override
public void subscribe(ObservableEmitter<Boolean> emitter) throws Exception {
WebSocket webSocket = mWebSocketPool.get(url);
if (webSocket == null) {
emitter.onError(new IllegalStateException("The WebSocket not open"));
} else {
emitter.onNext(webSocket.send(msg));
}
}
});
}
@Override
public Observable<Boolean> send(String url, ByteString byteString) {
return Observable.create(new ObservableOnSubscribe<Boolean>() {
@Override
public void subscribe(ObservableEmitter<Boolean> emitter) throws Exception {
WebSocket webSocket = mWebSocketPool.get(url);
if (webSocket == null) {
emitter.onError(new IllegalStateException("The WebSocket not open"));
} else {
emitter.onNext(webSocket.send(byteString));
}
}
});
}
@Override
public Observable<Boolean> asyncSend(String url, String msg) {
return getWebSocket(url)
.take(1)
.map(new Function<WebSocket, Boolean>() {
@Override
public Boolean apply(WebSocket webSocket) throws Exception {
return webSocket.send(msg);
}
});
}
@Override
public Observable<Boolean> asyncSend(String url, ByteString byteString) {
return getWebSocket(url)
.take(1)
.map(new Function<WebSocket, Boolean>() {
@Override
public Boolean apply(WebSocket webSocket) throws Exception {
return webSocket.send(byteString);
}
});
}
@Override
public Observable<Boolean> close(String url) {
return Observable.create(new ObservableOnSubscribe<WebSocket>() {
@Override
public void subscribe(ObservableEmitter<WebSocket> emitter) throws Exception {
WebSocket webSocket = mWebSocketPool.get(url);
if (webSocket == null) {
emitter.onError(new NullPointerException("url:" + url + " WebSocket must be not null"));
} else {
emitter.onNext(webSocket);
}
}
}).map(new Function<WebSocket, Boolean>() {
@Override
public Boolean apply(WebSocket webSocket) throws Exception {
return closeWebSocket(webSocket);
}
});
}
@Override
public boolean closeNow(String url) {
return closeWebSocket(mWebSocketPool.get(url));
}
@Override
public Observable<List<Boolean>> closeAll() {
return Observable
.just(mWebSocketPool)
.map(new Function<Map<String, WebSocket>, Collection<WebSocket>>() {
@Override
public Collection<WebSocket> apply(Map<String, WebSocket> webSocketMap) throws Exception {
return webSocketMap.values();
}
})
.concatMap(new Function<Collection<WebSocket>, ObservableSource<WebSocket>>() {
@Override
public ObservableSource<WebSocket> apply(Collection<WebSocket> webSockets) throws Exception {
return Observable.fromIterable(webSockets);
}
}).map(new Function<WebSocket, Boolean>() {
@Override
public Boolean apply(WebSocket webSocket) throws Exception {
return closeWebSocket(webSocket);
}
}).collect(new Callable<List<Boolean>>() {
@Override
public List<Boolean> call() throws Exception {
return new ArrayList<>();
}
}, new BiConsumer<List<Boolean>, Boolean>() {
@Override
public void accept(List<Boolean> list, Boolean isCloseSuccess) throws Exception {
list.add(isCloseSuccess);
}
}).toObservable();
}
@Override
public void closeAllNow() {
for (Map.Entry<String, WebSocket> entry : mWebSocketPool.entrySet()) {
closeWebSocket(entry.getValue());
}
}
/**
* 是否有连接
*/
private boolean hasWebSocketConnection(String url) {
return mWebSocketPool.get(url) != null;
}
/**
* 关闭WebSocket连接
*/
private boolean closeWebSocket(WebSocket webSocket) {
if (webSocket == null) {
return false;
}
WebSocketCloseEnum normalCloseEnum = WebSocketCloseEnum.USER_EXIT;
boolean result = webSocket.close(normalCloseEnum.getCode(), normalCloseEnum.getReason());
if (result) {
removeUrlWebSocketMapping(webSocket);
}
return result;
}
/**
* 移除Url和WebSocket的映射
*/
private void removeUrlWebSocketMapping(WebSocket webSocket) {
for (Map.Entry<String, WebSocket> entry : mWebSocketPool.entrySet()) {
if (entry.getValue() == webSocket) {
String url = entry.getKey();
mObservableCacheMap.remove(url);
mWebSocketPool.remove(url);
}
}
}
private void removeWebSocketCache(WebSocket webSocket) {
for (Map.Entry<String, WebSocket> entry : mWebSocketPool.entrySet()) {
if (entry.getValue() == webSocket) {
String url = entry.getKey();
mWebSocketPool.remove(url);
}
}
}
public Observable<WebSocket> getWebSocket(String url) {
return getWebSocketInfo(url)
.filter(new Predicate<WebSocketInfo>() {
@Override
public boolean test(WebSocketInfo webSocketInfo) throws Exception {
return webSocketInfo.getWebSocket() != null;
}
})
.map(new Function<WebSocketInfo, WebSocket>() {
@Override
public WebSocket apply(WebSocketInfo webSocketInfo) throws Exception {
return webSocketInfo.getWebSocket();
}
});
}
public Observable<WebSocketInfo> getWebSocketInfo(String url) {
return getWebSocketInfo(url, 5, TimeUnit.SECONDS);
}
public synchronized Observable<WebSocketInfo> getWebSocketInfo(final String url, final long timeout, final TimeUnit timeUnit) {
//先从缓存中取
Observable<WebSocketInfo> observable = mObservableCacheMap.get(url);
if (observable == null) {
//缓存中没有，新建
observable = Observable
.create(new WebSocketOnSubscribe(url))
.retry()
//因为有share操作符，只有当所有观察者取消注册时，这里才会回调
.doOnDispose(new Action() {
@Override
public void run() throws Exception {
//所有都不注册了，关闭连接
closeNow(url);
Logger.d(TAG, "所有观察者都取消注册，关闭连接...");
}
})
//Share操作符，实现多个观察者对应一个数据源
.share()
//将回调都放置到主线程回调，外部调用方直接观察，实现响应回调方法做UI处理
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread());
//将数据源缓存
mObservableCacheMap.put(url, observable);
} else {
//缓存中有，从连接池中取出
WebSocket webSocket = mWebSocketPool.get(url);
if (webSocket != null) {
observable = observable.startWith(createConnect(url, webSocket));
}
}
return observable;
}
/**
* 组装数据源
*/
private final class WebSocketOnSubscribe implements ObservableOnSubscribe<WebSocketInfo> {
private String mWebSocketUrl;
private WebSocket mWebSocket;
private boolean isReconnecting = false;
public WebSocketOnSubscribe(String webSocketUrl) {
this.mWebSocketUrl = webSocketUrl;
}
@Override
public void subscribe(ObservableEmitter<WebSocketInfo> emitter) throws Exception {
//因为retry重连不能设置延时，所以只能这里延时，降低发送频率
if (mWebSocket == null && isReconnecting) {
if (Thread.currentThread() != Looper.getMainLooper().getThread()) {
long millis = mReconnectIntervalTimeUnit.toMillis(mReconnectInterval);
if (millis == 0) {
millis = 1000;
}
SystemClock.sleep(millis);
}
}
initWebSocket(emitter);
}
private Request createRequest(String url) {
return new Request.Builder().get().url(url).build();
}
/**
* 初始化WebSocket
*/
private synchronized void initWebSocket(ObservableEmitter<WebSocketInfo> emitter) {
if (mWebSocket == null) {
mWebSocket = mClient.newWebSocket(createRequest(mWebSocketUrl), new WebSocketListener() {
@Override
public void onOpen(WebSocket webSocket, Response response) {
super.onOpen(webSocket, response);
//连接成功
if (!emitter.isDisposed()) {
mWebSocketPool.put(mWebSocketUrl, mWebSocket);
//重连成功
if (isReconnecting) {
emitter.onNext(createReconnect(mWebSocketUrl, webSocket));
} else {
emitter.onNext(createConnect(mWebSocketUrl, webSocket));
}
}
isReconnecting = false;
}
@Override
public void onMessage(WebSocket webSocket, String text) {
super.onMessage(webSocket, text);
//收到消息
if (!emitter.isDisposed()) {
emitter.onNext(createReceiveStringMsg(mWebSocketUrl, webSocket, text));
}
}
@Override
public void onMessage(WebSocket webSocket, ByteString bytes) {
super.onMessage(webSocket, bytes);
//收到消息
if (!emitter.isDisposed()) {
emitter.onNext(createReceiveByteStringMsg(mWebSocketUrl, webSocket, bytes));
}
}
@Override
public void onClosed(WebSocket webSocket, int code, String reason) {
super.onClosed(webSocket, code, reason);
if (!emitter.isDisposed()) {
emitter.onNext(createClose(mWebSocketUrl));
}
}
@Override
public void onFailure(WebSocket webSocket, Throwable throwable, Response response) {
super.onFailure(webSocket, throwable, response);
isReconnecting = true;
mWebSocket = null;
//移除WebSocket缓存，retry重试重新连接
removeWebSocketCache(webSocket);
if (!emitter.isDisposed()) {
emitter.onNext(createPrepareReconnect(mWebSocketUrl));
//失败发送onError，让retry操作符重试
emitter.onError(new ImproperCloseException());
}
}
});
}
}
}
private WebSocketInfo createConnect(String url, WebSocket webSocket) {
return mWebSocketInfoPool.obtain(url)
.setWebSocket(webSocket)
.setConnect(true);
}
private WebSocketInfo createReconnect(String url, WebSocket webSocket) {
return mWebSocketInfoPool.obtain(url)
.setWebSocket(webSocket)
.setReconnect(true);
}
private WebSocketInfo createPrepareReconnect(String url) {
return mWebSocketInfoPool.obtain(url)
.setPrepareReconnect(true);
}
private WebSocketInfo createReceiveStringMsg(String url, WebSocket webSocket, String stringMsg) {
return mWebSocketInfoPool.obtain(url)
.setConnect(true)
.setWebSocket(webSocket)
.setStringMsg(stringMsg);
}
private WebSocketInfo createReceiveByteStringMsg(String url, WebSocket webSocket, ByteString byteMsg) {
return mWebSocketInfoPool.obtain(url)
.setConnect(true)
.setWebSocket(webSocket)
.setByteStringMsg(byteMsg);
}
private WebSocketInfo createClose(String url) {
return mWebSocketInfoPool.obtain(url);
}
}
定时发送心跳维持连接
因为WebSocket断线后，后端不能马上知道连接已经断开，所以需要一个心跳消息保持双方通信。
实现心跳，本质就是一个定时消息，我们使用RxJava的interval操作符定时执行任务，这里我的消息需要增加一个时间戳，所以我加上了timestamp操作符来给每一次执行结果附加一个时间戳。
- 心跳信息json的生成，我们期望外部进行生成，例如Gson序列化为Json，或者FastJson处理，或者增加其他通用参数等，不应该在WebSocket基础库中写，所以提供了一个HeartBeatGenerateCallback回调进行生成Json。
- 这里我做了一个优化，当网络没有开启时，则不发送心跳消息。
public class NetworkUtil {
private NetworkUtil() {
}
/**
* 当前是否有网络状态
*
* @param context 上下文
* @param needWifi 是否需要wifi网络
*/
public static boolean hasNetWorkStatus(Context context, boolean needWifi) {
NetworkInfo info = getActiveNetwork(context);
if (info == null) {
return false;
}
if (!needWifi) {
return info.isAvailable();
} else if (info.getType() == ConnectivityManager.TYPE_WIFI) {
return info.isAvailable();
}
return false;
}
/**
* 获取活动网络连接信息
*
* @param context 上下文
* @return NetworkInfo
*/
public static NetworkInfo getActiveNetwork(Context context) {
ConnectivityManager mConnMgr = (ConnectivityManager) context
.getSystemService(Context.CONNECTIVITY_SERVICE);
if (mConnMgr == null) {
return null;
}
// 获取活动网络连接信息
return mConnMgr.getActiveNetworkInfo();
}
}
- 心跳回调接口，让外部生成心跳json
public interface HeartBeatGenerateCallback {
/**
* 当需要生成心跳信息时回调
*
* @param timestamp 当前时间戳
* @return 要发送的心跳信息
*/
String onGenerateHeartBeatMsg(long timestamp);
}
- 发送心跳消息，需要制定Url地址、间隔时间，间隔时间单位，心跳消息生成回调。
@Override
public Observable<Boolean> heartBeat(String url, int period, TimeUnit unit,
HeartBeatGenerateCallback heartBeatGenerateCallback) {
if (heartBeatGenerateCallback == null) {
return Observable.error(new NullPointerException("heartBeatGenerateCallback == null"));
}
return Observable
.interval(period, unit)
//timestamp操作符，给每个事件加一个时间戳
.timestamp()
.retry()
.flatMap(new Function<Timed<Long>, ObservableSource<Boolean>>() {
@Override
public ObservableSource<Boolean> apply(Timed<Long> timed) throws Exception {
long timestamp = timed.time();
//判断网络，存在网络才发消息，否则直接返回发送心跳失败
if (mContext != null && NetworkUtil.hasNetWorkStatus(mContext, false)) {
String heartBeatMsg = heartBeatGenerateCallback.onGenerateHeartBeatMsg(timestamp);
Logger.d(TAG, "发送心跳消息: " + heartBeatMsg);
if (hasWebSocketConnection(url)) {
return send(url, heartBeatMsg);
} else {
//这里必须用异步发送，如果切断网络，再重连，缓存的WebSocket会被清除，此时再重连网络
//是没有WebSocket连接可用的，所以就需要异步连接完成后，再发送
return asyncSend(url, heartBeatMsg);
}
} else {
Logger.d(TAG, "无网络连接，不发送心跳，下次网络连通时，再次发送心跳");
return Observable.create(new ObservableOnSubscribe<Boolean>() {
@Override
public void subscribe(ObservableEmitter<Boolean> emitter) throws Exception {
emitter.onNext(false);
}
});
}
}
});
}
实现重连
重连配置RxJava，有个天然优势就是RxJava提供了Retry操作符，支持重试，我们在onFailure()连接失败回调中手动发出onError()，让数据源增加retry操作符进行重试，就会重新走到数据源的订阅回调重新连接WebSocket。
private final class WebSocketOnSubscribe implements ObservableOnSubscribe<WebSocketInfo> {
private String mWebSocketUrl;
private WebSocket mWebSocket;
private boolean isReconnecting = false;
public WebSocketOnSubscribe(String webSocketUrl) {
this.mWebSocketUrl = webSocketUrl;
}
@Override
public void subscribe(ObservableEmitter<WebSocketInfo> emitter) throws Exception {
//...
}
private Request createRequest(String url) {
return new Request.Builder().get().url(url).build();
}
/**
* 初始化WebSocket
*/
private synchronized void initWebSocket(ObservableEmitter<WebSocketInfo> emitter) {
if (mWebSocket == null) {
mWebSocket = mClient.newWebSocket(createRequest(mWebSocketUrl), new WebSocketListener() {
@Override
public void onOpen(WebSocket webSocket, Response response) {
super.onOpen(webSocket, response);
//连接成功
if (!emitter.isDisposed()) {
mWebSocketPool.put(mWebSocketUrl, mWebSocket);
//重连成功
if (isReconnecting) {
emitter.onNext(createReconnect(mWebSocketUrl, webSocket));
} else {
emitter.onNext(createConnect(mWebSocketUrl, webSocket));
}
}
isReconnecting = false;
}
@Override
public void onMessage(WebSocket webSocket, String text) {
super.onMessage(webSocket, text);
//收到消息
if (!emitter.isDisposed()) {
emitter.onNext(createReceiveStringMsg(mWebSocketUrl, webSocket, text));
}
}
@Override
public void onMessage(WebSocket webSocket, ByteString bytes) {
super.onMessage(webSocket, bytes);
//收到消息
if (!emitter.isDisposed()) {
emitter.onNext(createReceiveByteStringMsg(mWebSocketUrl, webSocket, bytes));
}
}
@Override
public void onClosed(WebSocket webSocket, int code, String reason) {
super.onClosed(webSocket, code, reason);
if (!emitter.isDisposed()) {
emitter.onNext(createClose(mWebSocketUrl));
}
}
@Override
public void onFailure(WebSocket webSocket, Throwable throwable, Response response) {
super.onFailure(webSocket, throwable, response);
isReconnecting = true;
mWebSocket = null;
//移除WebSocket缓存，retry重试重新连接
removeWebSocketCache(webSocket);
if (!emitter.isDisposed()) {
emitter.onNext(createPrepareReconnect(mWebSocketUrl));
//失败发送onError，让retry操作符重试
emitter.onError(new ImproperCloseException());
}
}
});
}
}
}
使用
- 使用RxWebSocketBuilder，构建RxWebSocket
//自定义OkHttpClient
OkHttpClient mClient = new OkHttpClient.Builder()
.readTimeout(3, TimeUnit.SECONDS)//设置读取超时时间
.writeTimeout(3, TimeUnit.SECONDS)//设置写的超时时间
.connectTimeout(3, TimeUnit.SECONDS)//设置连接超时时间
.build();
//RxWebSocketBuilder构建RxWebSocket
RxWebSocket rxWebSocket = new RxWebSocketBuilder(context)
//是否打印Log
.isPrintLog(true)
//5秒无响应则重连
.reconnectInterval(5, TimeUnit.SECONDS)
.client(mClient)
.build();
- 连接Url地址
String url = "ws://xxxxxxxxx"
//开始连接
rxWebSocket.get(url)
//切换到子线程去连接
.compose(RxSchedulerUtil.ioToMain())
//绑定生命周期
.as(RxLifecycleUtil.bindLifecycle(mLifecycleOwner))
.subscribe(new Consumer<WebSocketInfo>() {
@Override
public void accept(WebSocketInfo webSocketInfo) throws Exception {
String json = webSocketInfo.getStringMsg();
//业务层的json解析
...
}
});
- 同步发送消息（必须确保连接正常，否则发送失败）
rxWebSocket.send(url, "我是消息")
.compose(RxSchedulerUtil.ioToMain())
.as(RxLifecycleUtil.bindLifecycle(mLifecycleOwner))
.subscribe(new Consumer<Boolean>() {
@Override
public void accept(Boolean isSuccess) throws Exception {
if(isSuccess) {
//发送成功
} ele {
//发送失败
}
}
});
- 异步发送消息（不需要确保连接正常，如果未连接会连接成功后自动发送）
rxWebSocket.asyncSend(url, "我是消息")
.compose(RxSchedulerUtil.ioToMain())
.as(RxLifecycleUtil.bindLifecycle(mLifecycleOwner))
.subscribe(new Consumer<Boolean>() {
@Override
public void accept(Boolean isSuccess) throws Exception {
if(isSuccess) {
//发送成功
} ele {
//发送失败
}
}
});
- 发送心跳包
rxWebSocket.heartBeat(url, 6 ,TimeUnit.SECONDS, new HeartBeatGenerateCallback() {
@Override
public String onGenerateHeartBeatMsg(long timestamp) {
//生成心跳Json，业务模块处理，例如后端需要秒值，我们除以1000换算为秒。
//后续可以在这里配置通用参数等
return GsonUtil.toJson(new HeartBeatMsgRequestModel(WssCommandTypeEnum.HEART_BEAT.getCode(),
String.valueOf(timestamp / 1000)));
}
});
总结
Okhttp的WebSocket使用比较简单，基本都是发起请求和配置回调2个步骤，再使用send()方法发送消息。
但如果真正使用起来还需要做一层封装，可以配合RxJava将异步回调封装成Observable通知订阅者，并使用RxJava的各种操作符，例如数据转换、线程切换、连接重试和心跳等。
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