Android进阶——Sharedpreferences保存对象和图片等复杂类型的数据

1、Android进阶Sharedpreferences保存对象和图片等复杂类型的数据一、保存和读取基本数据类型1、保存基本类型的数据 /* * 根据传入的prefereces的文件名设置指定key-valeu *param context * param preferenceName SharedPreferences的name * param key 对应的Key键 * param object 对应的各种类型的值 */ public static void saveKeyValue(Context context, String preferenceName, String key, Obj

2、ect object) SharedPreferences sharedPreferences=context.getSharedPreferences(preferenceName,context.MODE_PRIVATE); SharedPreferences.Editor editor=sharedPreferences.edit(); if (object instanceof String) editor.putString(key, (String) object); else if (object instanceof Integer) editor.putInt(key, (I

3、nteger) object); else if (object instanceof Boolean) editor.putBoolean(key, (Boolean) object); else if (object instanceof Float) editor.putFloat(key, (Float) object); else if (object instanceof Long) editor.putLong(key, (Long) object); else editor.putString(key, object.toString(); mit(); 2、读取基本类型的数据

4、 /* * 根据传入的prefereces的文件名设置指定key-valeu *param context * param preferenceName SharedPreferences的name * param key 对应的Key键 * param object 对应的各种类型的值 */ public static Object getValueByKey(Context context, String preferenceName,String key,Object object) SharedPreferences sharedPreferences=context.getShare

5、dPreferences(preferenceName,context.MODE_PRIVATE); if (object instanceof String) return sharedPreferences.getString(key, (String) object); else if (object instanceof Integer) return sharedPreferences.getInt(key, (Integer) object); else if (object instanceof Boolean) return sharedPreferences.getBoole

6、an(key, (Boolean) object); else if (object instanceof Float) return sharedPreferences.getFloat(key, (Float) object); else if (object instanceof Long) return sharedPreferences.getLong(key, (Long) object); else return sharedPreferences.getString(key, object.toString(); 二、保存和读取图片SharedPreferences原则上只能将

7、字符串以key-value的形式保存， 但是万物皆二进制，所以我们可以采用编码的方式将任何二进制数据转化为字符串， 从而将可以将二进制数据保存在SharedPreferences文件中，而最常用的编码格式是Base64.1、保存二进制数据 /* * param context * param preferenceName * param resId * param key */ public static void saveDrawable(Context context, String preferenceName,int resId,String key) SharedPreference

8、s sharedPreferences=context.getSharedPreferences(preferenceName,context.MODE_PRIVATE); SharedPreferences.Editor editor=sharedPreferences.edit(); Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), resId); ByteArrayOutputStream baos = new ByteArrayOutputStream(); press(Bitmap.Compres

9、sFormat.PNG, 50, baos); String imageBase64 = new String(Base64.encodeToString(baos.toByteArray(),Base64.DEFAULT); editor.putString(key,imageBase64 ); mit();2、读取二进制数据 public static Drawable getDrawableByKey(Context context, String preferenceName,String key) SharedPreferences sharedPreferences=context

10、.getSharedPreferences(preferenceName,context.MODE_PRIVATE); String emp = sharedPreferences.getString(key, ""); ByteArrayInputStream bais = new ByteArrayInputStream(Base64.decode(temp.getBytes(), Base64.DEFAULT); return Drawable.createFromStream(bais, ""); 三、保存和读取序列化的对象由于二进制数据经过编码

11、后可以用SharedPreferences以字符串的形式存储，所以保存对象也成为了可能，但是这个类必须是可序列化即implements Serializable（实际上Serializable接口是个空接口，只是为了标记该对象是被序列化的），然后可以通过ObjectOutputStream保存再转为二进制存储。1、保存序列化的对象 /* * param user */ public static void saveUser(Context context, String preferenceName,String key,User user) throws Exception if(user

12、instanceof Serializable) SharedPreferences sharedPreferences = context.getSharedPreferences(preferenceName, context.MODE_PRIVATE); SharedPreferences.Editor editor = sharedPreferences.edit(); ByteArrayOutputStream baos = new ByteArrayOutputStream(); try ObjectOutputStream oos = new ObjectOutputStream

13、(baos); oos.writeObject(user);/把对象写到流里 String temp = new String(Base64.encode(baos.toByteArray(), Base64.DEFAULT); editor.putString(key, temp); mit(); catch (IOException e) e.printStackTrace(); else throw new Exception("User must implements Serializable"); 2、读取序列化的对象 public static User get

14、User(Context context, String preferenceName,String key) SharedPreferences sharedPreferences=context.getSharedPreferences(preferenceName,context.MODE_PRIVATE); String temp = sharedPreferences.getString(key, ""); ByteArrayInputStreambais=new ByteArrayInputStream(Base64.decode(temp.getBytes()

15、, Base64.DEFAULT); User user = null; try ObjectInputStream ois = new ObjectInputStream(bais); user = (User) ois.readObject(); catch (IOException e) catch(ClassNotFoundException e1) return user; 当然Sharedpreferences也是可以存储各种集合类的比如说List，都可以通过转为ObjectOutputStream输出流进而编码存储： public static String listToStri

16、ng(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 byteArrayOutputStream = new ByteArrayOutputStream(); / 然后将得到的字符数据装载到ObjectOutputStream ObjectOutputStream objectOutputStream = new ObjectOutputStream( byteArrayOutputStream); / writeObject 方法负

17、责写入特定类的对象的状态，以便相应的 readObject 方法可以还原它 objectOutputStream.writeObject(list); / 最后，用Base64.encode将字节文件转换成Base64编码保存在String中 String listString = new String(Base64.encode( byteArrayOutputStream.toByteArray(), Base64.DEFAULT); / 关闭objectOutputStream objectOutputStream.close(); return listString; Suppress

18、Warnings("unchecked") public static List<?> StringToList(String listString) throws StreamCorruptedException, IOException, ClassNotFoundException byte mobileBytes = Base64.decode(listString.getBytes(), Base64.DEFAULT); ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStre

19、am( mobileBytes); ObjectInputStream objectInputStream = new ObjectInputStream( byteArrayInputStream); List<?> WeatherList = (List<?>) objectInputStream .readObject(); objectInputStream.close(); return WeatherList; 测试代码（SharedpreferesUtil就是自己写的工具类）：/* * Sharedpreferences 保存复杂数据 */public c

20、lass MainActivity extends Activity butterknife.Bind(R.id.save_list_btn) Button saveListBtn; butterknife.Bind(R.id.save_img_btn) Button saveImgBtn; butterknife.Bind(R.id.save_obj_btn) Button saveObjBtn; butterknife.Bind(R.id.show_imv) ImageView showImv; butterknife.Bind(R.id.imfo_edt) EditText imfoEd

21、t; butterknife.Bind(R.id.activity_main) RelativeLayout activityMain; private final static String SHAREDPREFS_USER="user_config" private final static String USER_AVATAR="avatar" private static final String USER_IMFO = "user" Override protected void onCreate(Bundle savedI

22、nstanceState) super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); butterknife.ButterKnife.bind(this); TargetApi(Build.VERSION_CODES.JELLY_BEAN) OnClick(R.id.save_img_btn,R.id.save_list_btn,R.id.save_obj_btn) void OnClick(View v) switch (v.getId() case R.id.save_img_btn: if(&q

23、uot;read Image".equals(saveImgBtn.getText() Drawable drawable=SharedpreferesUtil.getDrawableByKey(this, SHAREDPREFS_USER, USER_AVATAR); showImv.setVisibility(View.VISIBLE); /showImv.setBackgroundResource(R.mipmap.ic_launcher); showImv.setImageBitmap(IOUtil.drawableToBitmap(drawable); else Share

24、dpreferesUtil.saveDrawable(this, SHAREDPREFS_USER, R.mipmap.ic_launcher, USER_AVATAR); saveImgBtn.setText("read Image"); break; case R.id.save_list_btn: break; case R.id.save_obj_btn: if("read object".equals(saveObjBtn.getText() showImv.setVisibility(View.GONE); User user=Sharedp

25、referesUtil.getUser(this,SHAREDPREFS_USER,USER_IMFO); imfoEdt.setVisibility(View.VISIBLE); imfoEdt.setText("Id:"+user.get_id()+" Name:"+user.getName(); else try SharedpreferesUtil.saveUser(this, SHAREDPREFS_USER, USER_IMFO, new User(1001, "CrazyMo"); saveObjBtn.setText("read object"); catch (Exception e) e.printStackTrace(); break; def