Android中数据的封存和提取

package com.sky;

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

public class saveData extends Activity {
??? /** Called when the activity is first created. */
public static final String SETTING_INFOS = "SETTING_Infos";
public static final String NAME = "NAME";
public static final String PASSWORD = "PASSWORD";
private EditText field_name;? //接收用户名的组件
private EditText filed_pass;? //接收密码的组件
@Override
??? public void onCreate(Bundle savedInstanceState) {
??????? super.onCreate(savedInstanceState);
??????? setContentView(R.layout.main);
??????? field_name = (EditText) findViewById(R.id.EditText01);? //首先获取用来输入用户名的组件
??????? filed_pass = (EditText) findViewById(R.id.EditText02); //同时也需要获取输入密码?

??????? // Restore preferences
??????? //获取一个SharedPreferences对象，SETTING_INFOS与SETTING_INFOS.XML文件相对应
??????? //效果相当于读取SETTING_INFOS.XML文件，如果文件不存在，则进行创建
??????? SharedPreferences settings = getSharedPreferences(SETTING_INFOS, 0);
??????? //取出保存的NAME，取出改字段名的值，不存在则创建默认为空
??????? String name = settings.getString(NAME, "");?
??????? String password = settings.getString(PASSWORD, ""); //取出保存的PASSWORD，同上
??????? field_name.setText(name);? //将取出来的用户名赋予field_name
??????? filed_pass.setText(password);? //将取出来的密码赋予filed_pass
??????
??????? setTitle(name+password);//将NAME和PASSWORD显示在标题栏
??? }

@Override
protected void onStop()
{
? // TODO Auto-generated method stub
? super.onStop();
? //打开SETTING_INFOS.XML
? //0表示打开模式，有则读，没有则创建
? SharedPreferences settings = getSharedPreferences(SETTING_INFOS, 0);

//下面一句的语法比较神奇，每次执行都返回一个setting.edit(),commit()表示执行
? settings.edit()
? .putString(NAME, field_name.getText().toString())
? .putString(PASSWORD, filed_pass.getText().toString())
? .commit();//将field_name赋值给NAME字段，将filed_pass赋值给PASSWORD字段
}

}
//要查看录入的数据，进到DDMS->File Explorer /<package name>/shared_prefs/SETTING_INFOS.XML