创建一次性活动的共享首选项

我有三个活动A, B和C，其中A和B是表单，并在数据库(SQLite)中填充和保存表单数据后。我使用意图从A到B，然后从B到C，我想要的是，每次我打开我的应用程序时，我想要C作为我的主屏幕，而不再是A和B。

我想共享偏好可以解决这个问题，但我找不到一个好的例子来给我一个起点。

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小开
最佳答案

在“偏好”中设置值:

// MY_PREFS_NAME - a static String variable like:
//public static final String MY_PREFS_NAME = "MyPrefsFile";
SharedPreferences.Editor editor = getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE).edit();
editor.putString("name", "Elena");
editor.putInt("idName", 12);
editor.apply();

从首选项检索数据:

SharedPreferences prefs = getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE);
String name = prefs.getString("name", "No name defined");//"No name defined" is the default value.
int idName = prefs.getInt("idName", 0); //0 is the default value.

更多信息:

Using Shared Preferences .

共享偏好

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如何初始化?

// 0 - for private mode`
SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref", 0);


Editor editor = pref.edit();

如何在共享偏好中存储数据?

editor.putString("key_name", "string value"); // Storing string

或

editor.putInt("key_name", "int value"); //Storing integer

别忘了申请:

editor.apply();

如何从共享首选项检索数据?

pref.getString("key_name", null); // getting String


pref.getInt("key_name", 0); // getting Integer

希望这对你有帮助:)

小开

创建SharedPreferences

SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref", MODE_PRIVATE);
Editor editor = pref.edit();

将数据存储为KEY/VALUE对

editor.putBoolean("key_name1", true);           // Saving boolean - true/false
editor.putInt("key_name2", "int value");        // Saving integer
editor.putFloat("key_name3", "float value");    // Saving float
editor.putLong("key_name4", "long value");      // Saving long
editor.putString("key_name5", "string value");  // Saving string


// Save the changes in SharedPreferences
editor.apply(); // commit changes

获取SharedPreferences数据

//如果key的值不存在，则返回第二个参数值-在这种情况下为空

boolean userFirstLogin= pref.getBoolean("key_name1", true);  // getting boolean
int pageNumber=pref.getInt("key_name2", 0);             // getting Integer
float amount=pref.getFloat("key_name3", null);          // getting Float
long distance=pref.getLong("key_name4", null);          // getting Long
String email=pref.getString("key_name5", null);         // getting String

从SharedPreferences中删除Key值

editor.remove("key_name3"); // will delete key key_name3
editor.remove("key_name4"); // will delete key key_name4


// Save the changes in SharedPreferences
editor.apply(); // commit changes

清除SharedPreferences中的所有数据

 editor.clear();
editor.apply(); // commit changes
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public class Preferences {


public static final String PREF_NAME = "your preferences name";


@SuppressWarnings("deprecation")
public static final int MODE = Context.MODE_WORLD_WRITEABLE;


public static final String USER_ID = "USER_ID_NEW";
public static final String USER_NAME = "USER_NAME";


public static final String NAME = "NAME";
public static final String EMAIL = "EMAIL";
public static final String PHONE = "PHONE";
public static final String address = "address";


public static void writeBoolean(Context context, String key, boolean value) {
getEditor(context).putBoolean(key, value).commit();
}


public static boolean readBoolean(Context context, String key,
boolean defValue) {
return getPreferences(context).getBoolean(key, defValue);
}


public static void writeInteger(Context context, String key, int value) {
getEditor(context).putInt(key, value).commit();


}


public static int readInteger(Context context, String key, int defValue) {
return getPreferences(context).getInt(key, defValue);
}


public static void writeString(Context context, String key, String value) {
getEditor(context).putString(key, value).commit();


}


public static String readString(Context context, String key, String defValue) {
return getPreferences(context).getString(key, defValue);
}


public static void writeFloat(Context context, String key, float value) {
getEditor(context).putFloat(key, value).commit();
}


public static float readFloat(Context context, String key, float defValue) {
return getPreferences(context).getFloat(key, defValue);
}


public static void writeLong(Context context, String key, long value) {
getEditor(context).putLong(key, value).commit();
}


public static long readLong(Context context, String key, long defValue) {
return getPreferences(context).getLong(key, defValue);
}


public static SharedPreferences getPreferences(Context context) {
return context.getSharedPreferences(PREF_NAME, MODE);
}


public static Editor getEditor(Context context) {
return getPreferences(context).edit();
}


}

****使用Preferences写入值使用:-****

Preferences.writeString(getApplicationContext(),
Preferences.NAME, "dev");

****使用Preferences读取值使用:-****

Preferences.readString(getApplicationContext(), Preferences.NAME,
"");
小开

Shared Preferences是XML文件，用于以键值对的形式存储私有基元数据。数据类型包括布尔值， 浮点数， 整数， 多头和字符串。

当我们想要保存一些在整个应用程序中都可以访问的数据时，一种方法是将其保存在全局变量中。但是一旦应用程序关闭，它就会消失。另一种推荐的方法是保存在SharedPreference中。保存在SharedPreferences文件中的数据在整个应用程序中都可以访问，即使在应用程序关闭或重新启动之后也可以继续保存。

SharedPreferences以键值对的形式保存数据，并且可以以相同的方式访问。

你可以使用两个方法创建SharedPreferences的Object:

1). __abc1:使用这个方法你可以创建多个SharedPreferences。和它的第一个参数SharedPreferences的名字。

2). __abc1:使用此方法可以创建单个SharedPreferences。

存储数据

添加变量声明/创建首选项文件

public static final String PREFERENCES_FILE_NAME = "MyAppPreferences";

检索文件名的句柄(使用getSharedPreferences)

SharedPreferences settingsfile= getSharedPreferences(PREFERENCES_FILE_NAME,0);

打开编辑器和添加键值对

SharedPreferences.Editor myeditor = settingsfile.edit();
myeditor.putBoolean("IITAMIYO", true);
myeditor.putFloat("VOLUME", 0.7)
myeditor.putInt("BORDER", 2)
myeditor.putLong("SIZE", 12345678910L)
myeditor.putString("Name", "Amiyo")
myeditor.apply();

不要忘记如上所示使用myeditor.apply()应用/保存。

检索数据

 SharedPreferences mysettings= getSharedPreferences(PREFERENCES_FILE_NAME, 0);
IITAMIYO = mysettings.getBoolean("IITAMIYO", false);
//returns value for the given key.
//second parameter gives the default value if no user preference found
// (set to false in above case)
VOLUME = mysettings.getFloat("VOLUME", 0.5)
//0.5 being the default value if no volume preferences found
// and similarly there are get methods for other data types
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Initialise here..
SharedPreferences msharedpref = getSharedPreferences("msh",
MODE_PRIVATE);
Editor editor = msharedpref.edit();


store data...
editor.putString("id",uida); //uida is your string to be stored
editor.commit();
finish();




fetch...
SharedPreferences prefs = this.getSharedPreferences("msh", Context.MODE_PRIVATE);
uida = prefs.getString("id", "");
小开
共享偏好是如此容易学习，所以看看这个 关于sharedpreference

的简单教程 
import android.os.Bundle;
import android.preference.PreferenceActivity;


public class UserSettingActivity extends PreferenceActivity {


@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);


addPreferencesFromResource(R.xml.settings);


}
}
小开

创建SharedPreference和全局使用的最佳方法是创建一个类，如下所示:

public class PreferenceHelperDemo {
private final SharedPreferences mPrefs;


public PreferenceHelperDemo(Context context) {
mPrefs = PreferenceManager.getDefaultSharedPreferences(context);
}


private String PREF_Key= "Key";


public String getKey() {
String str = mPrefs.getString(PREF_Key, "");
return str;
}


public void setKey(String pREF_Key) {
Editor mEditor = mPrefs.edit();
mEditor.putString(PREF_Key, pREF_Key);
mEditor.apply();
}


}
小开

您可以创建自定义的SharedPreference类

public class YourPreference {
private static YourPreference yourPreference;
private SharedPreferences sharedPreferences;


public static YourPreference getInstance(Context context) {
if (yourPreference == null) {
yourPreference = new YourPreference(context);
}
return yourPreference;
}


private YourPreference(Context context) {
sharedPreferences = context.getSharedPreferences("YourCustomNamedPreference",Context.MODE_PRIVATE);
}


public void saveData(String key,String value) {
SharedPreferences.Editor prefsEditor = sharedPreferences.edit();
prefsEditor .putString(key, value);
prefsEditor.commit();
}


public String getData(String key) {
if (sharedPreferences!= null) {
return sharedPreferences.getString(key, "");
}
return "";
}
}

你可以像这样获得你的偏好实例:

YourPreference yourPrefrence = YourPreference.getInstance(context);
yourPreference.saveData(YOUR_KEY,YOUR_VALUE);


String value = yourPreference.getData(YOUR_KEY);
小开 
SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putInt(getString(R.string.saved_high_score), newHighScore);
editor.commit();
小开

写入共享首选项

SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putInt(getString(R.string.saved_high_score), newHighScore);
editor.commit();

从共享首选项读取

SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
int defaultValue = getResources().getInteger(R.string.saved_high_score_default);
long highScore = sharedPref.getInt(getString(R.string.saved_high_score), defaultValue);
小开

你也可以看看我过去的示例项目，是为此目的而写的。我在本地保存一个名称，并在用户请求或应用程序启动时检索它。

但是，在这个时候，最好使用commit(而不是apply)来持久化数据。更多信息在这里。

小开 
        // Create object of SharedPreferences.
SharedPreferences sharedPref = getSharedPreferences("mypref", 0);


//now get Editor
SharedPreferences.Editor editor = sharedPref.edit();


//put your value
editor.putString("name", required_Text);


//commits your edits
editor.commit();


// Its used to retrieve data
SharedPreferences sharedPref = getSharedPreferences("mypref", 0);
String name = sharedPref.getString("name", "");


if (name.equalsIgnoreCase("required_Text")) {
Log.v("Matched","Required Text Matched");
} else {
Log.v("Not Matched","Required Text Not Matched");
}
小开

我只是发现上面所有的例子都太混乱了，所以我自己写了一个。如果您知道自己在做什么，那么代码片段是很好的，但是像我这样不知道的人呢?

想要一个剪切-粘贴的解决方案?好了，就是这里!

创建一个新的java文件并将其称为Keystore。然后粘贴以下代码:

import android.content.Context;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.util.Log;


public class Keystore { //Did you remember to vote up my example?
private static Keystore store;
private SharedPreferences SP;
private static String filename="Keys";


private Keystore(Context context) {
SP = context.getApplicationContext().getSharedPreferences(filename,0);
}


public static Keystore getInstance(Context context) {
if (store == null) {
Log.v("Keystore","NEW STORE");
store = new Keystore(context);
}
return store;
}


public void put(String key, String value) {//Log.v("Keystore","PUT "+key+" "+value);
Editor editor = SP.edit();
editor.putString(key, value);
editor.commit(); // Stop everything and do an immediate save!
// editor.apply();//Keep going and save when you are not busy - Available only in APIs 9 and above.  This is the preferred way of saving.
}


public String get(String key) {//Log.v("Keystore","GET from "+key);
return SP.getString(key, null);


}


public int getInt(String key) {//Log.v("Keystore","GET INT from "+key);
return SP.getInt(key, 0);
}


public void putInt(String key, int num) {//Log.v("Keystore","PUT INT "+key+" "+String.valueOf(num));
Editor editor = SP.edit();


editor.putInt(key, num);
editor.commit();
}




public void clear(){ // Delete all shared preferences
Editor editor = SP.edit();


editor.clear();
editor.commit();
}


public void remove(){ // Delete only the shared preference that you want
Editor editor = SP.edit();


editor.remove(filename);
editor.commit();
}
}

现在保存那个文件，忘了它吧。你受够了。现在回到你的活动，像这样使用它:

public class YourClass extends Activity{


private Keystore store;//Holds our key pairs


public YourSub(Context context){
store = Keystore.getInstance(context);//Creates or Gets our key pairs.  You MUST have access to current context!


int= store.getInt("key name to get int value");
string = store.get("key name to get string value");


store.putInt("key name to store int value",int_var);
store.put("key name to store string value",string_var);
}
}
小开 
SharedPreferences mPref;
SharedPreferences.Editor editor;


public SharedPrefrences(Context mContext) {
mPref = mContext.getSharedPreferences(Constant.SharedPreferences, Context.MODE_PRIVATE);
editor=mPref.edit();
}


public void setLocation(String latitude, String longitude) {
SharedPreferences.Editor editor = mPref.edit();
editor.putString("latitude", latitude);
editor.putString("longitude", longitude);
editor.apply();
}


public String getLatitude() {
return mPref.getString("latitude", "");
}


public String getLongitude() {
return mPref.getString("longitude", "");
}


public void setGCM(String gcm_id, String device_id) {
editor.putString("gcm_id", gcm_id);
editor.putString("device_id", device_id);
editor.apply();
}


public String getGCMId() {
return mPref.getString("gcm_id", "");
}


public String getDeviceId() {
return mPref.getString("device_id", "");
}




public void setUserData(User user){


Gson gson = new Gson();
String json = gson.toJson(user);
editor.putString("user", json);
editor.apply();
}
public User getUserData(){
Gson gson = new Gson();
String json = mPref.getString("user", "");
User user = gson.fromJson(json, User.class);
return user;
}


public void setSocialMediaStatus(SocialMedialStatus status){


Gson gson = new Gson();
String json = gson.toJson(status);
editor.putString("status", json);
editor.apply();
}
public SocialMedialStatus getSocialMediaStatus(){
Gson gson = new Gson();
String json = mPref.getString("status", "");
SocialMedialStatus status = gson.fromJson(json, SocialMedialStatus.class);
return status;
}

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