AndroidAnnotations——SharedPreferencesHelpers

SharedPreferencesHelpers

Since AndroidAnnotations 2.1

SharedPreferences helpers allow you to use Android  SharedPreferences, but in a typesafe manner, instead of using strings.

SharedPreferences辅助可以让你使用Android   SharedPreferences ，但是用了类型安全方式来代替strings。

Defining the preferences

First, you should create an interface annotated with  @SharedPref to define the SharedPreferences :

首先，你应该生成一个加了   @SharedPref 注解的接口来定义SharedPreferences：

@SharedPref
public interface MyPrefs {

        // The field name will have default value "John"
        @DefaultString("John")
        String name();

        // The field age will have default value 42
        @DefaultInt(42)
        int age();

        // The field lastUpdated will have default value 0
        long lastUpdated();

}

Based on that specification, AndroidAnnotations builds a SharedPreferences Helper that has the same name plus an underscore. You can get an instance of the generated helper in any enhanced class with the  @Pref annotation.

基于上述说明，AA会创建一个 SharedPreferences 辅助，它的文件名字和父类相同，只是附加一个下划线。你可以使用   @Pref   注解在任意优化的类中获取生成的辅助的实例。

Important: The type of the field  MUST be the generated class instead of the source class. It's the only exception in AA.

重要提示：字段类型 必须是生成类。这是AA中唯一的特例。

@EActivity
public class MyActivity extends Activity {

        @Pref
        MyPrefs_ myPrefs;
        
        // ...

}

You can then start using it:

然后你就可以开始使用了：

// Simple edit myPrefs.name().put("John");

// Batch edit myPrefs.edit()
  .name()
  .put("John")
  .age()
  .put(42)
  .apply();

// Preference clearing: myPrefs.clear();

// Check if a value exists: boolean nameExists = myPrefs.name().exists();

// Reading a value long lastUpdated = myPrefs.lastUpdated().get();

// Reading a value and providing a fallback default value long now = System.currentTimeMillis();
long lastUpdated = myPrefs.lastUpdated().getOr(now);

Default resource value

Since AndroidAnnotations 3.0

It's now possible to inject a default value from Android resources with  @DefaultRes:

目前可以使用   @DefaultRes 注解从Android资源注入默认值：

@SharedPref
public interface MyPrefs {
    @DefaultRes(R.string.defaultPrefName)
    String resourceName();

    @DefaultRes
    String defaultPrefAge();
}

Scope

Observe that you can name the shared preference by setting  value to one of the following:

需要注意的是你可以设置   value 为以下一项来命名 shared preference ：

• ACTIVITY, for a shared preference named MyActivity_MyPrefs;
• ACTIVITY, 则shared preference 命名为MyActivity_MyPrefs;
• ACTIVITY_DEFAULT, for a shared preference named MyActivity (also available throughactivity.getPreferences());
• ACTIVITY_DEFAULT, 则shared preference 命名为MyActivity (也可以通过activity.getPreferences()获取);
• APPLICATION_DEFAULT, for the default SharedPreference or UNIQUE, for a shared preference named MyPrefs.
• APPLICATION_DEFAULT, 默认为 SharedPreference 或者 UNIQUE, 则shared preference 命名为MyPrefs.

Therefore, if a single shared preference is needed for the interface defined,  in order to all activities of a given application to share the same preferences, the following should be used:

因此，假如需要一个单例shared preference，为了给定application的所有activity可以共享数据，可以使用以下方法：

@SharedPref(value=SharedPref.Scope.UNIQUE)
public interface MyPrefs {
...

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