Android存储登陆信息

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 String list2String(List 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 List 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 stringList = null ;
        try {
            stringList = (List) 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

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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 ; } }