从Delphi访问Android的SharedPreferences类 [英] Accessing Android's SharedPreferences class from Delphi

问题描述

我刚刚开始使用Delphi XE5的Android开发路径，并且正在尝试构建一个需要能够保留一些输入信息（配置）的简单应用程序。

我已经弄清楚，Android类 SharedPreferences 可能是最简单的方式来做，但我无法弄清楚如何从Delphi XE5 FMX Mobile访问这个类。

我已经尝试在帮助中搜索SharedPreferences ，但它什么也没有返回。另一方面，搜索共享首选项给了我太多的东西。

解决方案

简而言之， API单元到uses子句 - 您的案例中的关键是 AndroidApi.Jni.JavaTypes ， AndroidApi.Jni.App 和 AndroidApi.Jni.GraphicsContentViewText ，连同 FMX.Helpers.Android 为一些胶水代码 - 并调用它很像你可能在Java中。 Java类被暴露为具有初始J的接口类型;在实践中，Android API使用嵌套类很多，由于Delphi不支持嵌套接口类型，所以它们变为ParentClassName_ChildClassName：

  var 
 Prefs：JSharedPreferences; 
编辑器：JSharedPreferences_Editor; 
 I：整数; 
 F：单
 S：string; 
 begin 
 Prefs：= SharedActivity.getPreferences（TJActivity.JavaClass.MODE_PRIVATE）; 
编辑：= Prefs.edit; 
 Editor.putInt（StringToJString（'MyIntKey'），999）; 
 Editor.putFloat（StringToJString（'MyFloatKey'），123.456）; 
 Editor.putString（StringToJString（'MyStrKey'），StringToJString（'This is a test'））; 
 Editor.apply; 
 I：= Prefs.getInt（StringToJString（'MyIntKey'），0）; 
 F：= Prefs.getFloat（StringToJString（'MyFloatKey'），0）; 
 S：= Prefs.getString（StringToJString（'MyIntKey'），StringToJString（''））; 
  

说，我最近推出了一个简单的 TCustomIniFile descendant包裹 SharedPreferences API - 请参阅这里了解信息：

http://delphihaven.wordpress.com/2013/09/12/a -few-xe5-related-bits /

将API映射到 TCustomIniFile ，一个小我发现的问题是事实 SharedPreferences 键是强类型的，并且似乎没有一种方法可以提前找出给定键的类型（键在 TCustomIniFile ，相比之下，是弱键入）。因此，为了阅读，我使用 getAll 方法将所有键和值作为 Map / JMap （Java字典对象，换句话说），并从那里读取单个密钥。

I have just started on the Android development path using Delphi XE5, and am trying to build a simple application that needs to be able to persist some entered information (configuration).

I have figured out, that the Android class SharedPreferences probably is the easiest way to do this, but I can't figure out how to access this class from Delphi XE5 FMX Mobile.

I have tried searching for "SharedPreferences" in the help, but it returns nothing. A search for "Shared Preferences", on the other hand, gives me too much.

解决方案

In a nutshell, add the required API units to the uses clause - the key ones in your case are AndroidApi.Jni.JavaTypes, AndroidApi.Jni.App, and AndroidApi.Jni.GraphicsContentViewText, together with FMX.Helpers.Android for some glue code - and call it pretty much like you might in Java. Java classes are exposed as interface types with an initial J; in practice the Android API uses nested classes quite a lot, and since Delphi doesn't support nested interface types, these become ParentClassName_ChildClassName:

var
  Prefs: JSharedPreferences;
  Editor: JSharedPreferences_Editor;
  I: Integer;
  F: Single;
  S: string;
begin
  Prefs := SharedActivity.getPreferences(TJActivity.JavaClass.MODE_PRIVATE);
  Editor := Prefs.edit;
  Editor.putInt(StringToJString('MyIntKey'), 999);
  Editor.putFloat(StringToJString('MyFloatKey'), 123.456);
  Editor.putString(StringToJString('MyStrKey'), StringToJString('This is a test'));
  Editor.apply;
  I := Prefs.getInt(StringToJString('MyIntKey'), 0);
  F := Prefs.getFloat(StringToJString('MyFloatKey'), 0);
  S := Prefs.getString(StringToJString('MyIntKey'), StringToJString(''));

That said, I've recently put out a simple TCustomIniFile descendant that wraps the SharedPreferences API - see here for info:

http://delphihaven.wordpress.com/2013/09/12/a-few-xe5-related-bits/

In mapping the API to TCustomIniFile, one small issue I found is the fact SharedPreferences keys are strongly typed, and there doesn't seem to be a way to find out in advance what type a given key has (keys in TCustomIniFile, in contrast, are weakly typed). Because of this, for reading, I use the getAll method to retreive all keys and values as a Map/JMap (Java dictionary object in other words) and read individual keys from there.

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