這期內(nèi)容當(dāng)中小編將會(huì)給大家?guī)碛嘘P(guān)Android中怎么保證數(shù)據(jù)同步寫入磁盤，文章內(nèi)容豐富且以專業(yè)的角度為大家分析和敘述，閱讀完這篇文章希望大家可以有所收獲。

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在一些特定的工作場(chǎng)景中，我們把數(shù)據(jù)及時(shí)寫出磁盤，而不是暫時(shí)保存在系統(tǒng)的文件緩存區(qū)，防止掉電導(dǎo)致數(shù)據(jù)丟失

/** * Force all system buffers to synchronize with the underlying * device. This method returns after all modified data and * attributes of this FileDescriptor have been written to the * relevant device(s). In particular, if this FileDescriptor * refers to a physical storage medium, such as a file in a file * system, sync will not return until all in-memory modified copies * of buffers associated with this FileDescriptor have been * written to the physical medium. * * sync is meant to be used by code that requires physical * storage (such as a file) to be in a known state For * example, a class that provided a simple transaction facility * might use sync to ensure that all changes to a file caused * by a given transaction were recorded on a storage medium. * * sync only affects buffers downstream of this FileDescriptor. If * any in-memory buffering is being done by the application (for * example, by a BufferedOutputStream object), those buffers must * be flushed into the FileDescriptor (for example, by invoking * OutputStream.flush) before that data will be affected by sync. * * @exception SyncFailedException *    Thrown when the buffers cannot be flushed, *    or because the system cannot guarantee that all the *    buffers have been synchronized with physical media. * @since   JDK1.1 */public native void sync() throws SyncFailedException;

可能一看到這個(gè)場(chǎng)景，很多人會(huì)想到數(shù)據(jù)庫的事務(wù)，查看Android數(shù)據(jù)庫sqlite的源碼可以看到，數(shù)據(jù)庫事務(wù)只能保證n個(gè)操作，要么都執(zhí)行，要么都不執(zhí)行。數(shù)據(jù)庫事務(wù)在所有操作完成后，會(huì)提醒文件系統(tǒng)與磁盤同步，但是不會(huì)等到所有系統(tǒng)緩沖區(qū)與磁盤同步完成才返回！

FileDescriptor.getFd().sync();會(huì)強(qiáng)制所有系統(tǒng)緩沖區(qū)與磁盤同步File file = new File("/sdcard/a.txt");    try {      FileOutputStream outputStream = new FileOutputStream(file);      outputStream.write("kuangxf".getBytes());      outputStream.flush();      //強(qiáng)制文件系統(tǒng)刷新      outputStream.getFD().sync();    } catch (Exception e) {      e.printStackTrace();    }

上述就是小編為大家分享的Android中怎么保證數(shù)據(jù)同步寫入磁盤了，如果剛好有類似的疑惑，不妨參照上述分析進(jìn)行理解。如果想知道更多相關(guān)知識(shí)，歡迎關(guān)注創(chuàng)新互聯(lián)行業(yè)資訊頻道。