Android存储登陆信息

最新推荐文章于 2024-08-15 11:04:31 发布

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本文介绍了一种利用SharedPreferences结合序列化技术来存储复杂对象的方法，包括用户信息等，有效解决了传统SharedPreferences仅能存储简单类型数据的局限性。

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;
    }
     
}