15 Android 数据存储

package com.data.r;import android.app.Activity;import android.content.Context;import android.content.SharedPreferences;import android.content.SharedPreferences.Editor;import android.os.Bundle;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.Toast;public class StroeDataActivity extends Activity {    /** Called when the activity is first created. */private Button btn1,btn2;private static String FILE_NAME="hello";    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        btn1=(Button)findViewById(R.id.button1);        btn2=(Button)findViewById(R.id.button2);        btn1.setOnClickListener(listern1);        btn2.setOnClickListener(listern2);    }        OnClickListener listern1=new OnClickListener() {public void onClick(View v) {// TODO Auto-generated method stubSharedPreferences prefernces=getSharedPreferences(FILE_NAME, Context.MODE_PRIVATE);Editor editor=prefernces.edit();editor.putString("name", "Tom");editor.putString("password", "abc123");editor.commit();}}; OnClickListener listern2=new OnClickListener() {public void onClick(View v) {// TODO Auto-generated method stubSharedPreferences preferences=getSharedPreferences(FILE_NAME, Context.MODE_WORLD_READABLE);String str=preferences.getString("name", "abc123");Log.d(">>>>>>>>>>>>提示", str);Toast.makeText(StroeDataActivity.this, str+"是", Toast.LENGTH_LONG).show();}};}

Using Shared Preferences

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The SharedPreferences class provides a general framework that allows you to save and retrieve persistent key-value pairs of primitive data types. You can use SharedPreferences to save any primitive data: booleans, floats, ints, longs, and strings. This data will persist across user sessions (even if your application is killed).

User Preferences

Shared preferences are not strictly for saving "user preferences," such as what ringtone a user has chosen. If you're interested in creating user preferences for your application, seePreferenceActivity, which provides an Activity framework for you to create user preferences, which will be automatically persisted (using shared preferences).

To get a SharedPreferences object for your application, use one of two methods:

• getSharedPreferences() - Use this if you need multiple preferences files identified by name, which you specify with the first parameter.
• getPreferences() - Use this if you need only one preferences file for your Activity. Because this will be the only preferences file for your Activity, you don't supply a name.

To write values:

1. Call edit() to get aSharedPreferences.Editor.
2. Add values with methods such as putBoolean() andputString().
3. Commit the new values with commit()

To read values, use SharedPreferences methods such asgetBoolean() andgetString().

Here is an example that saves a preference for silent keypress mode in a calculator:

public class Calc extends Activity {    public static final String PREFS_NAME = "MyPrefsFile";    @Override    protected void onCreate(Bundle state){       super.onCreate(state);       . . .       // Restore preferences       SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);       boolean silent = settings.getBoolean("silentMode", false);       setSilent(silent);    }    @Override    protected void onStop(){       super.onStop();      // We need an Editor object to make preference changes.      // All objects are from android.context.Context      SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);      SharedPreferences.Editor editor = settings.edit();      editor.putBoolean("silentMode", mSilentMode);      // Commit the edits!      editor.commit();    }}