如何在 rxjava 中在 oncomplete 调用时取消订阅
在 rxjava 中，通常希望在 observable 的 oncomplete 事件上取消订阅，以防止进一步的事件发射。这可以通过设置 completablefuture 来实现。
非 android 环境中使用 rxjava 2.x 的示例
flowable 由持久层方法返回，作为调用方中的 result.getall(dbname.get(), strategy) 和 result.gettablecolumn(table)。
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public class consoleschemaflowableoutput implements schemaflowableoutput { private static final logger logger = loggerfactory.getlogger(consoleschemaflowableoutput.class); private volatile completablefuture<string> future = new completablefuture<>(); private atomicinteger count = new atomicinteger(0); @override public disposable flush(information information, flowable<table> table) throws schemaexportexception { disposable export_flush_complete = table.subscribe(tableins -> { system.out.println(printasciitable(tableins)); system.out.println(printasciicolumns(tableins.getcolumns())); system.out.println(" "); count.addandget(1); }, throwable -> { logger.debug("export break, reason: " + throwable.getmessage()); future.cancel(true); throw new schemaexportexception(throwable); }, new action() { @override public void run() throws exception { logger.debug("export complete, affect size:" + count.get()); future.complete("ok"); } }); return export_flush_complete; } @override public completablefuture<string> getfuture() { return future; } ... }
调用方
public void export(Information info, SchemaFlowableOutput out) throws SchemaExportException { long startStamp = System.currentTimeMillis(); // Flowable Flowable<Table> tableFlowable = result.getAll(dbName.get(), strategy).flatMap(new Function<Table, Publisher<Table>>() { @Override public Publisher<Table> apply(@NonNull Table table) throws Exception { return result.getTableColumn(table).flatMap(new Function<List<Column>, SingleSource<Table>>() { @Override public SingleSource<Table> apply(@NonNull List<Column> columns) throws Exception { return Single.just(table.fillColumn(columns)); } }).flatMapPublisher(new Function<Table, Publisher<? extends Table>>() { @Override public Publisher<? extends Table> apply(@NonNull Table table) throws Exception { return Flowable.just(table); } }); } }); Disposable disposable = null; try { disposable = out.flush(info, tableFlowable); CompletableFuture<String> future = out.getFuture(); while (!future.isDone()) { logger.info("[ERE-Flowable]未完成,线程休眠1秒"); Thread.currentThread().sleep(1000, 0); } String result = future.get(); logger.info("[ERE-Flowable]完成, 结果:" + result); if (result.equals("OK")) { long finishStamp = System.currentTimeMillis(); clearHander(disposable, "[ERE-Flowable]RxJava disposed because complete, WithTime: " + (finishStamp - startStamp)); } } catch (Exception e) { clearHander(disposable, "[ERE-Flowable]RxJava disposed has Exception: " + e.getMessage()); } } private void clearHander(Disposable disposable, String reason) { logger.info(reason); if (null != disposable && !disposable.isDisposed()) { disposable.dispose(); } else { if (null != disposable) { logger.info("[CH]disposable status:" + disposable.isDisposed()); } else { logger.info("[CH]disposable is null:"); } } // 结束后的回调,执行一些清理工作 completeHandler.apply(); }
通过将 completablefuture 设置为 “ok” 来通知调用方 observable 已结束，这将取消订阅并执行后续处理。
