Android 使用Singleton读写数据到SharedPreferences
示例
SharedPreferencesManager(Singleton)类用于读取和写入所有类型的数据。
import android.content.Context;
import android.content.SharedPreferences;
import android.util.Log;
import com.google.gson.Gson;
import java.lang.reflect.Type;
/**
* Singleton Class for accessing SharedPreferences,
* should be initialized once in the beginning by any application component using static
* method initialize(applicationContext)
*/
public class SharedPrefsManager {
private static final String TAG = SharedPrefsManager.class.getName();
private SharedPreferences prefs;
private static SharedPrefsManager uniqueInstance;
public static final String PREF_NAME = "com.example.app";
private SharedPrefsManager(Context appContext) {
prefs = appContext.getSharedPreferences(PREF_NAME, Context.MODE_PRIVATE);
}
/**
* Throws IllegalStateException if this class is not initialized
*
* @return unique SharedPrefsManager instance
*/
public static SharedPrefsManager getInstance() {
if (uniqueInstance == null) {
throw new IllegalStateException(
"SharedPrefsManager is not initialized, call initialize(applicationContext) " +
"static method first");
}
return uniqueInstance;
}
/**
* Initialize this class using application Context,
* should be called once in the beginning by any application Component
*
* @param appContext application context
*/
public static void initialize(Context appContext) {
if (appContext == null) {
throw new NullPointerException("Provided application context is null");
}
if (uniqueInstance == null) {
synchronized (SharedPrefsManager.class) {
if (uniqueInstance == null) {
uniqueInstance = new SharedPrefsManager(appContext);
}
}
}
}
private SharedPreferences getPrefs() {
return prefs;
}
/**
* Clears all data in SharedPreferences
*/
public void clearPrefs() {
SharedPreferences.Editoreditor = getPrefs().edit();
editor.clear();
editor.commit();
}
public void removeKey(String key) {
getPrefs().edit().remove(key).commit();
}
public boolean containsKey(String key) {
return getPrefs().contains(key);
}
public String getString(String key, String defValue) {
return getPrefs().getString(key, defValue);
}
public String getString(String key) {
return getString(key, null);
}
public void setString(String key, String value) {
SharedPreferences.Editoreditor = getPrefs().edit();
editor.putString(key, value);
editor.apply();
}
public int getInt(String key, int defValue) {
return getPrefs().getInt(key, defValue);
}
public int getInt(String key) {
return getInt(key, 0);
}
public void setInt(String key, int value) {
SharedPreferences.Editoreditor = getPrefs().edit();
editor.putInt(key, value);
editor.apply();
}
public long getLong(String key, long defValue) {
return getPrefs().getLong(key, defValue);
}
public long getLong(String key) {
return getLong(key, 0L);
}
public void setLong(String key, long value) {
SharedPreferences.Editoreditor = getPrefs().edit();
editor.putLong(key, value);
editor.apply();
}
public boolean getBoolean(String key, boolean defValue) {
return getPrefs().getBoolean(key, defValue);
}
public boolean getBoolean(String key) {
return getBoolean(key, false);
}
public void setBoolean(String key, boolean value) {
SharedPreferences.Editoreditor = getPrefs().edit();
editor.putBoolean(key, value);
editor.apply();
}
public boolean getFloat(String key) {
return getFloat(key, 0f);
}
public boolean getFloat(String key, float defValue) {
return getFloat(key, defValue);
}
public void setFloat(String key, Float value) {
SharedPreferences.Editoreditor = getPrefs().edit();
editor.putFloat(key, value);
editor.apply();
}
/**
* Persists an Object in prefs at the specified key, class of given Object must implement Model
* interface
*
* @param key String
* @param modelObject Object to persist
* @param <M> Generic for Object
*/
public <M extends Model> void setObject(String key, M modelObject) {
String value = createJSONStringFromObject(modelObject);
SharedPreferences.Editoreditor = getPrefs().edit();
editor.putString(key, value);
editor.apply();
}
/**
* Fetches the previously stored Object of given Class from prefs
*
* @param key String
* @param classOfModelObject Class of persisted Object
* @param <M> Generic for Object
* @return Object of given class
*/
public <M extends Model> M getObject(String key, Class<M> classOfModelObject) {
String jsonData = getPrefs().getString(key, null);
if (null != jsonData) {
try {
Gson gson = new Gson();
M customObject = gson.fromJson(jsonData, classOfModelObject);
return customObject;
} catch (ClassCastException cce) {
Log.d(TAG, "无法将从首选项获取的字符串转换为类型的集合 " +
classOfModelObject.getName() + "\n" + cce.getMessage());
}
}
return null;
}
/**
* Persists a Collection object in prefs at the specified key
*
* @param key String
* @param dataCollection Collection Object
* @param <C> Generic for Collection object
*/
public <C> void setCollection(String key, C dataCollection) {
SharedPreferences.Editoreditor = getPrefs().edit();
String value = createJSONStringFromObject(dataCollection);
editor.putString(key, value);
editor.apply();
}
/**
* Fetches the previously stored Collection Object of given type from prefs
*
* @param key String
* @param typeOfC Type of Collection Object
* @param <C> Generic for Collection Object
* @return Collection Object which can be casted
*/
public <C> C getCollection(String key, Type typeOfC) {
String jsonData = getPrefs().getString(key, null);
if (null != jsonData) {
try {
Gson gson = new Gson();
C arrFromPrefs = gson.fromJson(jsonData, typeOfC);
return arrFromPrefs;
} catch (ClassCastException cce) {
Log.d(TAG, "无法将从首选项获取的字符串转换为类型的集合 " +
typeOfC.toString() + "\n" + cce.getMessage());
}
}
return null;
}
public void registerPrefsListener(SharedPreferences.OnSharedPreferenceChangeListener listener) {
getPrefs().registerOnSharedPreferenceChangeListener(listener);
}
public void unregisterPrefsListener(
SharedPreferences.OnSharedPreferenceChangeListenerlistener) {
getPrefs().unregisterOnSharedPreferenceChangeListener(listener);
}
publicSharedPreferences.EditorgetEditor() {
return getPrefs().edit();
}
private static String createJSONStringFromObject(Object object) {
Gson gson = new Gson();
return gson.toJson(object);
}
}Modelinterface这是通过类的实现Gson来避免混淆的。
public interface Model {
}Model接口的Proguard规则：
-keep interface com.example.app.Model
-keep class * implements com.example.app.Model { *;}