android 保存用户名和密码设置等应用信息优化

此文为转载：为尊重原创作者添加原始链接：

http://www.cnblogs.com/likwo/p/3875909.html

1、传统的保存用户名，密码方式 SharedPreferences

Editor editor = shareReference.edit();
editor.putString(KEY_NAME,"username_value");

通过这样的方法，能够基本满足需求，比如有用户名，那么就Editor.putString存放就好。

但是这样的方法有一些弊端：

（1）在存放一些集合信息，存储ArrayList就不合适

（2）如果针对用户，新增加了很多熟悉，比如性别，头像等信息，那么需要一个一个的添加put和get方法，非常的繁琐。

2、通过序列化对象，将对象序列化成base64编码的文本，然后再通过SharedPreferences 保存，那么就方便很多，只需要在对象里增加get和set方法就好。

3、序列换通用方法，将list对象或者普通的对象序列化成字符串

package com.example.imagedemo;
 
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.StreamCorruptedException;
import java.util.List;
 
import android.util.Base64;
 
public class SerializableUtil {
     
    public static <E> String list2String(List<E> list) throws IOException{
        //实例化一个ByteArrayOutputStream对象，用来装载压缩后的字节文件
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        //然后将得到的字符数据装载到ObjectOutputStream
        ObjectOutputStream oos = new ObjectOutputStream(baos);
        //writeObject 方法负责写入特定类的对象的状态，以便相应的readObject可以还原它
        oos.writeObject(list);
        //最后，用Base64.encode将字节文件转换成Base64编码，并以String形式保存
        String listString = new String(Base64.encode(baos.toByteArray(),Base64.DEFAULT));
        //关闭oos
        oos.close();
        return listString;
        }
     
    public static  String obj2Str(Object obj)throws IOException
    {
        if(obj == null) {
            return "";
        }
              //实例化一个ByteArrayOutputStream对象，用来装载压缩后的字节文件
                ByteArrayOutputStream baos = new ByteArrayOutputStream();
                //然后将得到的字符数据装载到ObjectOutputStream
                ObjectOutputStream oos = new ObjectOutputStream(baos);
                //writeObject 方法负责写入特定类的对象的状态，以便相应的readObject可以还原它
                oos.writeObject(obj);
                //最后，用Base64.encode将字节文件转换成Base64编码，并以String形式保存
                String listString = new String(Base64.encode(baos.toByteArray(),Base64.DEFAULT));
                //关闭oos
                oos.close();
                return listString;
    } 
     
    //将序列化的数据还原成Object
    public static Object str2Obj(String str) throws StreamCorruptedException,IOException{
        byte[] mByte = Base64.decode(str.getBytes(),Base64.DEFAULT);
        ByteArrayInputStream bais = new ByteArrayInputStream(mByte);
        ObjectInputStream ois = new ObjectInputStream(bais);
         
        try {
            return ois.readObject();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
     
    }
     
    public static <E> List<E> string2List(String str) throws StreamCorruptedException,IOException{
        byte[] mByte = Base64.decode(str.getBytes(),Base64.DEFAULT);
        ByteArrayInputStream bais = new ByteArrayInputStream(mByte);
        ObjectInputStream ois = new ObjectInputStream(bais);
        List<E> stringList = null;
        try {
            stringList = (List<E>) ois.readObject();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return stringList;
        }
 
}

4、要保存的用户对象

package com.example.imagedemo;
 
import java.io.Serializable;
 
import android.annotation.SuppressLint;
 
 
public class UserEntity implements Serializable 
{
     private static final long serialVersionUID = -5683263669918171030L;  
 
    private String userName;
    // 原始密码
     
    public String getUserName()
    {
        return userName;
    }
 
    public void setUserName(String userName)
    {
        this.userName = userName;
    }
 
    public String getPassword()
    {
        return password;
    }
 
    public void setPassword(String password)
    {
        this.password = password;
    }
 
    private String password;
 
}

5、编写SharedPreUtil ，实现对对象的读取和保存

package com.example.imagedemo;
 
import java.io.IOException;
import java.io.StreamCorruptedException;
 
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
 
public class SharedPreUtil
{
     
    // 用户名key
    public final static String KEY_NAME = "KEY_NAME";
 
    public final static String KEY_LEVEL = "KEY_LEVEL";
     
     
    private static SharedPreUtil s_SharedPreUtil;
     
    private static UserEntity s_User = null;
 
    private SharedPreferences msp;
     
    // 初始化，一般在应用启动之后就要初始化
    public static synchronized void initSharedPreference(Context context)
    {
        if (s_SharedPreUtil == null)
        {
            s_SharedPreUtil = new SharedPreUtil(context);
        }
    }
     
    /**
     * 获取唯一的instance
     * 
     * @return
     */
    public static synchronized SharedPreUtil getInstance()
    {
        return s_SharedPreUtil;
    }
     
    public SharedPreUtil(Context context)
    {
        msp = context.getSharedPreferences("SharedPreUtil",
                Context.MODE_PRIVATE | Context.MODE_APPEND);
    }
     
    public SharedPreferences getSharedPref()
    {
        return msp;
    }
 
     
    public synchronized void putUser(UserEntity user)
    {
         
        Editor editor = msp.edit();
         
        String str="";
        try {
            str = SerializableUtil.obj2Str(user);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        editor.putString(KEY_NAME,str);
        editor.commit();
         
        s_User = user;
    }
     
    public synchronized UserEntity getUser()
    {
         
        if (s_User == null)
        {
            s_User = new UserEntity();
     
             
            //获取序列化的数据
            String str = msp.getString(SharedPreUtil.KEY_NAME, "");
             
            try {
                Object obj = SerializableUtil.str2Obj(str);
                if(obj != null){
                    s_User = (UserEntity)obj;
                }
                 
            } catch (StreamCorruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
         
        return s_User;
    }
     
    public synchronized void DeleteUser()
    {
        Editor editor = msp.edit();
        editor.putString(KEY_NAME,"");
     
        editor.commit();
        s_User = null;
    }
     
}

6、调用Activity代码

package com.example.imagedemo;
 
import android.app.Activity;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
 
public class ActivityMain extends Activity
{
     
    EditText edit_pwd;
    EditText edit_name;
    Button button;
     
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
         
        SharedPreUtil.initSharedPreference(getApplicationContext());
         
     
         
        edit_pwd = (EditText)findViewById(R.id.pwd);
        edit_name = (EditText)findViewById(R.id.name);
         
        button = (Button)findViewById(R.id.btn);
         
         
     //保存到本地
        button.setOnClickListener(new OnClickListener()
        {
             
            @Override
            public void onClick(View v)
            {
                 
                 String name  = edit_name.getText().toString();
                 String pwd = edit_pwd.getText().toString();
                  
                 UserEntity user = new UserEntity();
                 user.setPassword(pwd);
                 user.setUserName(name);
                  
                 //用户名，密码保存在SharedPreferences
                 SharedPreUtil.getInstance().putUser(user);             
            }
        });
        Button delBtn = (Button)findViewById(R.id.btn_del);
        delBtn.setOnClickListener(new OnClickListener()
            {
                 
                @Override
                public void onClick(View v)
                {   
                     SharedPreUtil.getInstance().DeleteUser();      
                       edit_name.setText("");
                       edit_pwd.setText("");
                }
            });
         
        UserEntity user = SharedPreUtil.getInstance().getUser();
        if(!TextUtils.isEmpty(user.getPassword()) && !TextUtils.isEmpty( user.getUserName() ) ){
            edit_name.setText(user.getUserName());
            edit_pwd.setText(user.getPassword());
        }
         
    }
     
    @Override
    public boolean onCreateOptionsMenu(Menu menu)
    {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
     
}

对应的布局文件

　来个截图

7、如果我们的应用程序有不太复杂的保存需求，那么就可借助 SerializableUtil list2String 将list对象保存为文本，然后在通过文本的方式来读取，这样就不用使用数据库了，会轻量很多。

相关阅读:
P2761 软件补丁问题
 CF1335F Robots on a Grid
[bzoj2088]P3505 [POI2010]TEL-Teleportation
CF1335E Three Blocks Palindrome
P3831 [SHOI2012]回家的路
 P4568 [JLOI2011]飞行路线（分层图）
P4774 [NOI2018]屠龙勇士
 P2480 [SDOI2010]古代猪文
 CF #632 (Div. 2) 对应题号CF1333
BSGS 和扩展
原文地址：https://www.cnblogs.com/liyuzhao/p/4013121.html

android 保存 用户名和密码 设置等应用信息优化

android 保存用户名和密码设置等应用信息优化