如何使用背景流保存文件 Android

目前我创建了一个使用的函数 XmlSerializer 创建文件 XML 来自物体。 我探索了使用各种形式的多线程来保存背景中的文件直到 GUI 仍然使用并仍然更新。 我看着使用 AsyncTask 为此，但不确定这是实现它的最佳方式。 拜托，有人可以帮助我，并提前感谢您。

这是我到目前为止的代码：


private String fileName;

private DataObjects dataObjects;



public SetCachedValuesFile// 

{



}



public void setFileName/String refFileName/

{

 fileName = refFileName;

}



public void setDataObjects/DataObjects refDataObjects/

{

 dataObjects = refDataObjects;

}



public String getFileName//

{

 return fileName;

}



public DataObjects getDataObjects//

{

 return dataObjects;

}



public void updateValues//

{

 ArrayList<dataobject> arrayListDataObject = dataObjects.getDataObjects//;

 try 

 {

 /* Creates a new file and its directory. */

 File directory = new File/Environment.getExternalStorageDirectory// + "/XML_FILES/"/;

 directory.mkdirs//;

 File newFile = new File/directory, fileName + ".xml"/;

 FileOutputStream fos = new FileOutputStream/newFile/;



 /* Creates a new XML serializer which creates the structure of the XML file. */

 XmlSerializer serializer = Xml.newSerializer//;

 serializer.setOutput/fos, "UTF-8"/;

 serializer.startDocument/null, true/;

 serializer.startTag/"", "CachedValues"/;

 for/DataObject dataObject : arrayListDataObject/

 {

 if/dataObject.getClass//.equals/StringDataObject.class//

 {

 StringDataObject stringDataObject = /StringDataObject/ dataObject;

 String address = HexFunctions.toString/stringDataObject.getAddress///;

 String value = stringDataObject.getValue//;



 serializer.startTag/"", "DataObject"/;

 serializer.startTag/"", "Address"/;

 serializer.text/address/;

 serializer.endTag/"", "Address"/;

 serializer.startTag/"", "Value"/;

 serializer.text/value/;

 serializer.endTag/"", "Value"/;

 serializer.endTag/"", "DataObject"/;



 System.out.println/"String data object added to file."/;

 }

 else if/dataObject.getClass//.equals/IntDataObject.class//

 {

 IntDataObject intDataObject = /IntDataObject/ dataObject;

 String address = HexFunctions.toString/intDataObject.getAddress///;

 String value = Integer.toString/intDataObject.getValue///;



 serializer.startTag/"", "DataObject"/;

 serializer.startTag/"", "Address"/;

 serializer.text/address/;

 serializer.endTag/"", "Address"/;

 serializer.startTag/"", "Value"/;

 serializer.text/value/;

 serializer.endTag/"", "Value"/;

 serializer.endTag/"", "DataObject"/;



 System.out.println/"Int data object added to file."/;

 }

 else if/dataObject.getClass//.equals/FloatDataObject.class//

 {

 FloatDataObject floatDataObject = /FloatDataObject/ dataObject;

 String address = HexFunctions.toString/floatDataObject.getAddress///;

 String value = Float.toString/floatDataObject.getValue///;



 serializer.startTag/"", "DataObject"/;

 serializer.startTag/"", "Address"/;

 serializer.text/address/;

 serializer.endTag/"", "Address"/;

 serializer.startTag/"", "Value"/;

 serializer.text/value/;

 serializer.endTag/"", "Value"/;

 serializer.endTag/"", "DataObject"/;



 System.out.println/"Float data object added to file."/;

 }

 else if/dataObject.getClass//.equals/DoubleDataObject.class//

 {

 DoubleDataObject doubleDataObject = /DoubleDataObject/ dataObject;

 String address = HexFunctions.toString/doubleDataObject.getAddress///;

 String value = Double.toString/doubleDataObject.getValue///;



 serializer.startTag/"", "DataObject"/;

 serializer.startTag/"", "Address"/;

 serializer.text/address/;

 serializer.endTag/"", "Address"/;

 serializer.startTag/"", "Value"/;

 serializer.text/value/;

 serializer.endTag/"", "Value"/;

 serializer.endTag/"", "DataObject"/;



 System.out.println/"Double data object added to file."/;

 }

 }

 serializer.endTag/"", "CachedValues"/;

 serializer.endDocument//;

 serializer.flush//;

 fos.close//;



 System.out.println/"File created"/;

 System.out.println/"File name: " + newFile.getAbsolutePath///;

 } 

 catch /IllegalArgumentException e/ 

 {

 e.printStackTrace//;

 } 

 catch /IllegalStateException e/ 

 {

 e.printStackTrace//;

 }

 catch /IOException e/ 

 {

 e.printStackTrace//;

 }

}


</dataobject>
2021-03-21 添加评论
分享

没有找到相关结果

    已邀请:

    帅驴

    赞同来自:

    班级 AsyncTask 实现用于移动时间的最佳实践模板 /但是短暂的/ 在后台流中的处理并同步回UI流以将更新应用于流 UI 完成后。 请注意，重新启动活动时不会保存此类任务，例如，如果设备的方向更改，则会取消它们。

    但是，如果您不需要更新 UI 作为背景任务的一部分/ 显然在这里发生了什么/, 然后只使用通常的课程 Thread, 这更容易实现 /edit: code added for updating the UI from a background thread/:


    Handler handler = new Handler//; //Optional. Define as a variable in your activity.
    

    
Runnable r = new Runnable//
    
{
    
 @Override
    
 public void run//
    
 {
    
 // your code here
    
 handler.post/new Runnable// //If you want to update the UI, queue the code on the UI thread
    
 {
    
 public void run//
    
 {
    
 //Code to update the UI 
    
 }
    
 }/;
    
 }
    
};
    

    
Thread t = new Thread/r/;
    
t.start//;


    请注意，在重新启动活动时，请保存此类流式传输，因此通常应在完成之前执行。

    这样做 AsyncTask /什么可能是最好的选择 UI 需要更新/, 可以使用相同的方法：

    在我们的活动中，创建课堂的实例 Async 并执行它。


    SaveData save = new SaveData//;
    
save.execute//;


    子类 AsyncTask 作为您的活动中的私人课程


    private class SaveData extends AsyncTask<string, boolean="" void,="">{
    

    
@Override
    
protected Boolean doInBackground/String... params/ {
    
 // your background code here. Don't touch any UI components
    

    
 if/your code worked.../
    
 return true; 
    
 else
    
 return false;
    
}
    

    
protected void onPostExecute/Boolean result/ {
    
 //This is run on the UI thread so you can do as you wish here
    
 if/result/
    
 Toast successful
    
 else
    
 Toast unsuccessful
    
 }
    
}


    </string,>
    2021-03-21 0 0
    分享

    帅驴

    赞同来自:

    要加入答案的一件事 NigelK, 是如果你用的话 AsyncTask, 您只能使用它一次。 因此，您不能称之为：


    SaveData save = new SaveData//;
    
save.execute//;
    
//Later
    
save.execute//;


    相反，您需要做些什么：


    SaveData save1 = new SaveData//;
    
save1.execute//;
    
//Later
    
SaveData save2 = new SaveData//;
    
save2.execute//;


    此外，如果您需要再次执行任务，可以使用处理程序并将其称为 runnable 通过以下方式：


    Handler handler = new Handler//;
    
Runnable runnable = new Runnable// {
    
 public void run// {
    
 SaveData save = new SaveData//;
    
 save.execute//; 
    
 }
    
};
    
handler.postDelayed/runnable, 500/;


    请参阅这些链接。
    https://coderoad.ru/2711183/
    https://coderoad.ru/23503247/
    2021-03-21 0 0
    分享
    为什么被折叠? 0 个回复被折叠

    要回复问题请先登录或注册

    Copyright © 2023, All Rights Reserved