持久对象在Windows XP / Delphi 7 [英] Persistent Objects in Windows XP/Delphi 7

问题描述

我试图在Delphi 7，Windows XP中制作一个AlarmSystem。我必须在数据库（MS SQL Server 2000）中注册警报。但是如果服务器关闭怎么办？嗯，我可以想象，我必须持有TAlarm类型的对象。那么我该怎么做呢？也许继承TComponent？请，我该怎么办？

非常感谢。

我很抱歉我的英文。

这里有更多的信息.​​..
TAlarm是一个从TObject下降的类，基本上是。还有10个班级从TAlarm（某些类型的闹钟）下降。 TAlarm有一个名为FParams：TParams的字段，子类只有一个Execute方法。 FParams可以是不同的类型：TAlarmX1_Params，TAlarmX2_Params等等。

解决方案

您可以继承TPersistent和那么您可以使用TJvAppXMLFileStorage（ JVCL ）组件来序列化TAlarm类。

保存对象

 使用
 JvAppXMLStorage; 
 
过程SaveMyObject（MyAlarm：TAlarm）
 var 
 MyStore：TJvAppXMLFileStorage; 
 begin 
 MyStore：= TJvAppXMLFileStorage.Create（nil）; 
 try 
 MyStore.WritePersistent（''，MyAlarm）; 
 MyStore.Xml.SaveToFile（'C：\MyAlarm.xml'）; 
 finally 
 MyStore.Free; 
结束
结束
  

还原对象

 使用
 JvAppXMLStorage; 
 
过程LoadMyObject（MyAlarm：TAlarm）
 var 
 MyStore：TJvAppXMLFileStorage; 
 begin 
 MyStore：= TJvAppXMLFileStorage.Create（nil）; 
 try 
 MyStore.FileName：='C：\MyAlarm.xml'; 
 MyStore.Xml.LoadFromFile（'C：\MyAlarm.xml'）; 
 MyStore.ReadPersistent（''，MyAlarm）; 
 finally 
 MyStore.Free; 
结束
结束
  

更新

如果您需要坚持XML文件的多个对象必须为WritePersistent和ReadPersistent方法分配一个路径（唯一ID）。

看到这个例子，

多重持久化

 过程SaveMyObjects （MyObjects：TComponent数组）; 
 var 
 MyStore：TJvAppXMLFileStorage; 
 i：integer; 
 begin 
 MyStore：= TJvAppXMLFileStorage.Create（nil）; 
尝试
为i：=低（MyObjects）到高（MyObjects）做
 MyStore.WritePersistent（MyObjects [i] .Name，MyObjects [i]）; //在这种情况下，我使用组件的name属性。 
 MyStore.Xml.SaveToFile（'C：\Tools\MyAlarm.xml'）; 
 finally 
 MyStore.Free; 
结束
结束
  

保存组件

  SaveMyObjects（[Button1，Button2，Edit1，Edit2]）; 
  

多个LOAD

 过程LoadMyObjects（MyObjects：TComponent的数组）; 
 var 
 MyStore：TJvAppXMLFileStorage; 
 i：integer; 
 
 begin 
 MyStore：= TJvAppXMLFileStorage.Create（nil）; 
 try 
 MyStore.FileName：='C：\Tools\MyAlarm.xml'; 
 MyStore.Xml.LoadFromFile（'C：\Tools\MyAlarm.xml'）; 
 for i：= Low（MyObjects）to High（MyObjects）do 
 MyStore.ReadPersistent（MyObjects [i] .Name，MyObjects [i]）; 
 finally 
 MyStore.Free; 
结束
结束
  

恢复属性

  LoadMyObjects（[Button1，Button2，Edit1，Edit2]）; 
  

加载

另一个选项

 过程LoadMyObjectById（Id：String; MyObject：TComponent）; //使用对象的id 
 var 
 MyStore：TJvAppXMLFileStorage; 
 i：integer; 
 
 begin 
 MyStore：= TJvAppXMLFileStorage.Create（nil）; 
 try 
 MyStore.FileName：='C：\Tools\MyAlarm.xml'; 
 MyStore.Xml.LoadFromFile（'C：\Tools\MyAlarm.xml'）; 
 MyStore.ReadPersistent（id，MyObject）; 
 finally 
 MyStore.Free; 
结束
结束
  

您必须以这种方式运行

  LoadMyObjectById（Button1.Name，Button1）; //再次使用Name属性。 
  

我希望这个例子会很有用;）

I am trying to make an AlarmSystem in Delphi 7, Windows XP. I have to register alarms in a Database (MS SQL Server 2000). But what if the server is down??? Well, I can imagine that I have to persist objects of TAlarm type. So, how can I do this? Maybe inheriting from TComponent??? Please, how can I do this??

Thanks a lot.

I am sorry about my English.

Here you have more info... TAlarm is a class that descends from TObject, basically. There are 10 more classes that descend from TAlarm (some types of alarms). TAlarm has a field named FParams : TParams, and the child classes only have an Execute method. The field FParams can be of different types: TAlarmX1_Params, TAlarmX2_Params, etc, etc, etc.

解决方案

You can inheriting from TPersistent and then you can use the TJvAppXMLFileStorage (JVCL) component to serialize the TAlarm class.

Save a Object

uses
  JvAppXMLStorage;

Procedure SaveMyObject(MyAlarm : TAlarm)
var
  MyStore: TJvAppXMLFileStorage;
begin
  MyStore:= TJvAppXMLFileStorage.Create(nil);
  try
    MyStore.WritePersistent('', MyAlarm);
    MyStore.Xml.SaveToFile('C:\MyAlarm.xml');
  finally
    MyStore.Free;
  end;
end;

Restore a Object

uses
  JvAppXMLStorage;

Procedure LoadMyObject(MyAlarm : TAlarm)
var
  MyStore: TJvAppXMLFileStorage;
begin
  MyStore:= TJvAppXMLFileStorage.Create(nil);
  try
    MyStore.FileName:='C:\MyAlarm.xml';        
    MyStore.Xml.LoadFromFile('C:\MyAlarm.xml');
    MyStore.ReadPersistent('', MyAlarm);
  finally
    MyStore.Free;
  end;
end;

UPDATE

If you need to persist more than one object to the XML file you must assign a path (unique id) to the WritePersistent and ReadPersistent methods.

See this example,

Multiple Persist

Procedure SaveMyObjects(MyObjects : Array of TComponent);
var
  MyStore: TJvAppXMLFileStorage;
  i      : integer;
begin
  MyStore:= TJvAppXMLFileStorage.Create(nil);
  try
    for i := Low(MyObjects) to High(MyObjects) do
     MyStore.WritePersistent(MyObjects[i].Name, MyObjects[i]); //In this case i use the name property of the component.
    MyStore.Xml.SaveToFile('C:\Tools\MyAlarm.xml');
   finally
    MyStore.Free;
  end;
end;

to save the components

SaveMyObjects([Button1,Button2,Edit1,Edit2]);

Multiple LOAD

Procedure LoadMyObjects(MyObjects:Array of TComponent);
var
  MyStore    : TJvAppXMLFileStorage;
  i          : integer;

begin
  MyStore:= TJvAppXMLFileStorage.Create(nil);
  try
    MyStore.FileName:='C:\Tools\MyAlarm.xml';
    MyStore.Xml.LoadFromFile('C:\Tools\MyAlarm.xml');
    for i := Low(MyObjects) to High(MyObjects) do
      MyStore.ReadPersistent(MyObjects[i].Name, MyObjects[i]);
  finally
    MyStore.Free;
  end;
end;

To restore the properties

LoadMyObjects([Button1,Button2,Edit1,Edit2]);

Another option to load

Procedure LoadMyObjectById(Id:String;MyObject:TComponent); //using the id of the object
var
  MyStore    : TJvAppXMLFileStorage;
  i          : integer;

begin
  MyStore:= TJvAppXMLFileStorage.Create(nil);
  try
    MyStore.FileName:='C:\Tools\MyAlarm.xml';
    MyStore.Xml.LoadFromFile('C:\Tools\MyAlarm.xml');
   MyStore.ReadPersistent(id, MyObject);
  finally
    MyStore.Free;
  end;
end;

you must run it this way

LoadMyObjectById(Button1.Name,Button1); //Again using the Name property.

I hope this example will be useful ;)

这篇关于持久对象在Windows XP / Delphi 7的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！