android-数据持久化

String FILE_NAME = "tempfile.tmp";
try { //读
FileInputStream fis = openFileInput(FILE_NAME);
InputStreamReader isr = new InputStreamReader(fis, "UTF-8");
BufferedReader br = new BufferedReader(isr);
StringBuffer sb = new StringBuffer();
while (br.readLine() != null) {
sb.append(br.readLine()+"\n");
}
System.out.println(sb.toString()); //写
FileOutputStream fos = openFileOutput(FILE_NAME, Context.MODE_PRIVATE);//要让其它应用组件也能访问则用MODE_WORLD_WRITEABLE
File file = new File(FILE_NAME);
if (!file.exists()) {
byte[] os = "write file".getBytes("UTF-8");//"这个例子测试文件写".getBytes("GB2312");
fos.write(os);
} } catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

//这个id是在gen的R.java中生成id. 项目层次结构为res/raw里
InputStream is = getResources().openRawResource(R.raw.info);
InputStreamReader isr;
isr = new InputStreamReader(is, "UTF-8");
BufferedReader bfr = new BufferedReader(isr);
String inString = "";
while ((inString = bfr.readLine()) != null) {
Log.i(TAG, inString);
}

int minimumMagnitude = 0;
boolean autoUpdate = false;
int updateFreq = 0;//读
Context context = getApplicationContext();
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context); minimumMagnitude = Integer.parseInt(prefs.getString(Preferences.PREF_MIN_MAG, "0"));
updateFreq = Integer.parseInt(prefs.getString(Preferences.PREF_UPDATE_FREQ, "0"));
autoUpdate = prefs.getBoolean(Preferences.PREF_AUTO_UPDATE, false);//写
Context context = getApplicationContext();
prefs = PreferenceManager.getDefaultSharedPreferences(context);
Editor editor = prefs.edit();
editor.putBoolean(PREF_AUTO_UPDATE, autoUpdateChecked);
editor.putInt(PREF_UPDATE_FREQ, updateIndex);
editor.putInt(PREF_MIN_MAG, minMagIndex);
editor.commit();

@res/xml/userpreferences.xml<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen
xmlns:android="http://schemas.android.com/apk/res/android">
<CheckBoxPreference
android:key="PREF_AUTO_UPDATE"
android:title="Auto refresh"
android:summary="Select to turn on automatic updating"
android:defaultValue="true"
/>
<ListPreference
android:key="PREF_UPDATE_FREQ"
android:title="Refresh frequency"
android:summary="Frequency at which to refresh earthquake list"
android:entries="@array/update_freq_options"
android:entryValues="@array/update_freq_values"
android:dialogTitle="Refresh frequency"
android:defaultValue="60"
/>
<ListPreference
android:key="PREF_MIN_MAG"
android:title="Minimum magnitude"
android:summary="Select the minimum magnitude earthquake to report"
android:entries="@array/magnitude_options"
android:entryValues="@array/magnitude"
android:dialogTitle="Magnitude"
android:defaultValue="3"
/>
</PreferenceScreen>@PreferencesActivitypublic void onCreate(Bundle icicle) {
super.onCreate(icicle);
addPreferencesFromResource(R.xml.userpreferences);
}

@Activitypublic void onCreate(Bundle icicle) {
Context context = getApplicationContext();
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
prefs.registerOnSharedPreferenceChangeListener(this);
} public void onSharedPreferenceChanged(SharedPreferences prefs, String key) {
}

private ListView myListView;
private EditText myEditText;
private static final String TEXT_ENTRY_KEY = "TEXT_ENTRY_KEY";
private static final String ADDING_ITEM_KEY = "ADDING_ITEM_KEY";public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); // Inflate your view
setContentView(R.layout.main); // Get references to UI widgets
myListView = (ListView)findViewById(R.id.myListView);
myEditText = (EditText)findViewById(R.id.myEditText); restoreUIState();
}private void restoreUIState() {
// Get the activity preferences object.
SharedPreferences settings = getPreferences(0); // Read the UI state values, specifying default values.
String text = settings.getString(TEXT_ENTRY_KEY, "");
Boolean adding = settings.getBoolean(ADDING_ITEM_KEY, false); // Restore the UI to the previous state.
if (adding) {
addNewItem();
myEditText.setText(text);
}
}@Override
protected void onPause() {
super.onPause(); // Get the activity preferences object.
SharedPreferences uiState = getPreferences(0);
// Get the preferences editor.
SharedPreferences.Editor editor = uiState.edit(); // Add the UI state preference values.
editor.putString(TEXT_ENTRY_KEY, myEditText.getText().toString());
editor.putBoolean(ADDING_ITEM_KEY, addingNew);
// Commit the preferences.
editor.commit();
}

private static final String SELECTED_INDEX_KEY = "SELECTED_INDEX_KEY";@Override
public void onSaveInstanceState(Bundle outState) {
outState.putInt(SELECTED_INDEX_KEY, myListView.getSelectedItemPosition()); super.onSaveInstanceState(outState);
} @Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
int pos = -1; if (savedInstanceState != null)
if (savedInstanceState.containsKey(SELECTED_INDEX_KEY))
pos = savedInstanceState.getInt(SELECTED_INDEX_KEY, -1); myListView.setSelection(pos);
}