Android数据存储之SharedPreferences

       有些时候,应用程序有少量的数据需要保存,而且这些数据的格式很简单,都是普通的字符串. 标量类型的值等,Android提供了SharedPreferences进行保存。SharedPreferences处理的就是一个key-value(键值对)。从用法角度来看,SharedPreferences和SharedPreferences.Editor组合起来非常Map,其中SharedPreferences负责根据Key读取数据。而SharedPreferences.Editor则用于写入数据。

下面通过一个简单实例来说明:

1.XML

 1 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2     xmlns:tools="http://schemas.android.com/tools"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     android:paddingBottom="@dimen/activity_vertical_margin"
 6     android:paddingLeft="@dimen/activity_horizontal_margin"
 7     android:paddingRight="@dimen/activity_horizontal_margin"
 8     android:paddingTop="@dimen/activity_vertical_margin"
 9     tools:context=".MainActivity" >
10 
11     <Button
12         android:id="@+id/button1"
13         android:layout_width="wrap_content"
14         android:layout_height="wrap_content"
15         android:text="保存数据到SharedPreferences" />
16 
17     <Button
18         android:id="@+id/button2"
19         android:layout_width="wrap_content"
20         android:layout_height="wrap_content"
21         android:text="获取SharedPreferences中的数据" />
22 
23 </RelativeLayout>

2.java代码:

 1 package com.example.sharedpreferences;
 2 
 3 import android.os.Bundle;
 4 import android.app.Activity;
 5 import android.content.Context;
 6 import android.content.SharedPreferences;
 7 import android.view.Menu;
 8 import android.view.View;
 9 import android.view.View.OnClickListener;
10 import android.widget.Button;
11 import android.widget.Toast;
12 
13 public class MainActivity extends Activity {
14 
15     private Button button;
16     private Button button2;
17 
18     @Override
19     protected void onCreate(Bundle savedInstanceState) {
20         super.onCreate(savedInstanceState);
21         setContentView(R.layout.activity_main);
22         button = (Button) this.findViewById(R.id.button1);
23         button2 = (Button) this.findViewById(R.id.button2);
24         button.setOnClickListener(new OnClickListener() {
25             @Override
26             public void onClick(View arg0) {
27                 saveSharPreference(MainActivity.this);
28             }
29         });
30         button2.setOnClickListener(new OnClickListener() {
31             @Override
32             public void onClick(View arg0) {
33                 getSharedPreference();
34             }
35         });
36     }
37 
38     // 保存数据到sharedPreferennes
39     private void saveSharPreference(Context context) {
40         SharedPreferences sharedPreferences = getSharedPreferences("user",
41                 Activity.MODE_PRIVATE); // 实例化SharedPreferences对象
42         SharedPreferences.Editor editor = sharedPreferences.edit(); // 实例化SharedPreferences.Editor对象
43         editor.putString("userid", "11");
44         editor.putString("username", "summer");
45         editor.commit();
46         Toast.makeText(this, "数据成功写入SharedPreferences!", Toast.LENGTH_LONG)
47                 .show();
48     }
49 
50     // 从SharedPreferences获取数据
51     private void getSharedPreference() {
52         SharedPreferences sharedPreferences = getSharedPreferences("user",
53                 Activity.MODE_PRIVATE);
54         // 使用getString方法获得value,注意第2个参数是value的默认值
55         String userId = sharedPreferences.getString("userid", "");
56         String userName = sharedPreferences.getString("username", "");
57         Toast.makeText(
58                 this,
59                 "读取数据如下:" + "\n" + "userid:" + userId + "\n" + "username:"
60                         + userName, Toast.LENGTH_LONG).show();
61     }
62 }

 

posted @ 2014-11-14 14:59  Summers  阅读(257)  评论(0编辑  收藏  举报