Android中共享偏好的奇怪问题

我正在尝试使用共享首选项来存储我的应用程序设置，但即使我尽可能地复制教程，我仍然无法使其正常工作。以下是我的课程：

public class ActivitySettings extends PreferenceActivity {

@SuppressWarnings("unused")
private static String TAG = "ActivitySettings";

private static final String PREFS_NAME = "preferences";

private static final String DISABLE_CHECK = "disableCheck";
private static final String ALWAYS_CONFIRM = "alwaysConfirm";
private static final String NEVER_CONFIRM = "neverConfirm";
private static final String SHOW_NOTIFICATION = "showNotification";
private static final String SHOW_ON_BOOT = "showOnBoot";
private static final String HIDE_ICON = "hideIcon";
private static final String LOGGING = "logging";

private Context context = this;

private CheckBoxPreference disableCodeCheck;
private CheckBoxPreference alwaysAskForConf;
private CheckBoxPreference neverAskForConf;
private CheckBoxPreference showNotif;
private CheckBoxPreference showAtBoot;
private CheckBoxPreference hideIcon;
private Preference exportData;
private Preference importData;
private Preference cleanUp;
private Preference reset;
private CheckBoxPreference logging;

private boolean isDisableCodeCheck;
private boolean isAlwaysAskForConf;
private boolean isNeverAskForConf;
private boolean isShowNotif;
private boolean isShowAtBoot;
private boolean isHideIcon;
private boolean isLogging;

private void loadPreferences() {
    SharedPreferences prefs = getSharedPreferences(PREFS_NAME, 0);

    isDisableCodeCheck = prefs.getBoolean(DISABLE_CHECK, false);
    isAlwaysAskForConf = prefs.getBoolean(ALWAYS_CONFIRM, false);
    isNeverAskForConf = prefs.getBoolean(NEVER_CONFIRM, false);
    isShowNotif = prefs.getBoolean(SHOW_NOTIFICATION, false);
    isShowAtBoot = prefs.getBoolean(SHOW_ON_BOOT, false);
    isHideIcon = prefs.getBoolean(HIDE_ICON, false);
    isLogging = prefs.getBoolean(LOGGING, false);
}

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

    addPreferencesFromResource(R.xml.settings);

    disableCodeCheck = (CheckBoxPreference) findPreference("disable_code_check");
    alwaysAskForConf = (CheckBoxPreference) findPreference("always_ask_for_conf");
    neverAskForConf = (CheckBoxPreference) findPreference("never_ask_for_conf");
    showNotif = (CheckBoxPreference) findPreference("show_notif");
    showAtBoot = (CheckBoxPreference) findPreference("show_at_boot");
    hideIcon = (CheckBoxPreference) findPreference("hide_icon");
    exportData = findPreference("exp");
    importData = findPreference("imp");
    cleanUp = findPreference("clean_up");
    reset = findPreference("reset");
    logging = (CheckBoxPreference) findPreference("logging");

    loadPreferences();

    //here are also booleans modified

@Override
protected void onStop() {
    super.onStop();
    savePreferences();
}

private void savePreferences() {
    SharedPreferences prefs = getSharedPreferences(PREFS_NAME, 0);

    prefs.edit().putBoolean(DISABLE_CHECK, isDisableCodeCheck);
    prefs.edit().putBoolean(ALWAYS_CONFIRM, isAlwaysAskForConf);
    prefs.edit().putBoolean(NEVER_CONFIRM, isNeverAskForConf);
    prefs.edit().putBoolean(SHOW_NOTIFICATION, isShowNotif);
    prefs.edit().putBoolean(SHOW_ON_BOOT, isShowAtBoot);
    prefs.edit().putBoolean(HIDE_ICON, isHideIcon);
    prefs.edit().putBoolean(LOGGING, isLogging);

    prefs.edit().commit();
}

}

发生的情况如下：

在shared_prefs中创建了两个文件：preferences.xml和packagename_preferences.xml。不知道为什么，提供了PREFS_名称

加载设置是用onCreate方法完成的，保存和提交是在onStop中完成的

使用adb shell和cat，我在应用程序运行时查看文件，下面是场景：

• 我打开设置并勾选某物，packagename_preferences.xml以正确的值创建
• 我按下back键，创建了第二个文件-preferences.xml，如下所示：

• 当我再次打开“设置”时，第一次运行时一切看起来都一样，packagename_preferences.xml中的值都更改为默认值（？）

我知道PreferenceActivity有内置机制，但我不想使用它，因为我需要从其他活动访问其他设置

---

编辑

---

我已经创建了这样的应用程序：

package pl.test;

import android.app.Activity;
import android.content.SharedPreferences;
import android.os.Bundle;

public class TestActivity extends Activity {
String s = "0";

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    SharedPreferences sp = getSharedPreferences("pref", 0);  
    s = sp.getString("setting2", "1");
    s = "5";
}

@Override
public void onStop() {
    super.onStop();
    SharedPreferences sp = getSharedPreferences("pref", 0);
    sp.edit().putString("setting2", s);
    sp.edit().commit();
}

}

---

它不起作用，只是不将字符串保存到pref.xml。怎么了

问题在于每次调用sp.edit（）都会生成一个新的编辑器对象。因此，您的调用sp.edit（）.commit（）正在创建一个新的编辑器，该编辑器没有要提交的更改。试试这个：

private void savePreferences() {
    SharedPreferences prefs = getSharedPreferences(PREFS_NAME, 0);
    SharedPreferences.Editor editor = prefs.edit(); 
    editor.putBoolean(DISABLE_CHECK, isDisableCodeCheck);
    editor.putBoolean(ALWAYS_CONFIRM, isAlwaysAskForConf);
    editor.putBoolean(NEVER_CONFIRM, isNeverAskForConf);
    editor.putBoolean(SHOW_NOTIFICATION, isShowNotif);
    editor.putBoolean(SHOW_ON_BOOT, isShowAtBoot);
    editor.putBoolean(HIDE_ICON, isHideIcon);
    editor.putBoolean(LOGGING, isLogging);
    editor.commit();
}

或者，编辑器方法被设计为链接，因此这也可以工作：

private void savePreferences() {
    SharedPreferences prefs = getSharedPreferences(PREFS_NAME, 0)
        prefs.edit().putBoolean(DISABLE_CHECK, isDisableCodeCheck)
        .putBoolean(ALWAYS_CONFIRM, isAlwaysAskForConf)
        .putBoolean(NEVER_CONFIRM, isNeverAskForConf)
        .putBoolean(SHOW_NOTIFICATION, isShowNotif)
        .putBoolean(SHOW_ON_BOOT, isShowAtBoot)
        .putBoolean(HIDE_ICON, isHideIcon)
        .putBoolean(LOGGING, isLogging)
        .commit();
}

您的测试代码中也存在同样的问题，可以这样修复：

@Override
public void onStop() {
    super.onStop();
    SharedPreferences sp = getSharedPreferences("pref", 0);
    sp.edit().putString("setting2", s).commit();
}

---

在读取第一个应用程序共享的世界可读数据时，我们应该

替换

getSharedPreferences("PREF_NAME", Context.MODE_PRIVATE);

与

---

在第二个应用中获取第二个应用中的更新值。

这没有帮助。仍然会创建两个文件，但不会加载设置。

getSharedPreferences("PREF_NAME", Context.MODE_MULTI_PROCESS);