3.4 存储简单数据的利器——Preferences

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.sample3_6"
    android:versionCode="1"
    android:versionName="1.0" >    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />    <application
        android:allowBackup="true"
        android:icon="@drawable/icon"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.sample3_6.MyActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application></manifest>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textSize="25dip"
        android:id="@+id/TextView01"        />                                               <!-- 添加TextView -->
</LinearLayout>

package com.example.sample3_6;import java.security.acl.LastOwnerException;
import java.util.Date;import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.view.Menu;
import android.view.View;
import android.widget.TextView;public class MyActivity extends Activity {    private TextView tv;    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        SharedPreferences sp = this.getSharedPreferences("sharePre", Context.MODE_PRIVATE);
        String lastLogin = sp.getString(
                "ll",        //键值
                null       //默认值
        );
     if(lastLogin ==null){
         lastLogin = "欢迎您,您是第一次访问本Preferences";
     }else{
        lastLogin =  "欢迎回来,您上次于" + lastLogin + "登录";
     }
     SharedPreferences.Editor editor = sp.edit();
     editor.putString("ll", new Date().toLocaleString());
     editor.commit();
     tv = (TextView) this.findViewById(R.id.TextView01);
     tv.setText(lastLogin);/*    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
*/
}
}