一、SharedPreferences

1.存储数据

步骤1：得到SharedPreferences对象 getSharedPreferences(“文件的名称”,“文件的类型”);
(1).Context.MODE_PRIVATE:指定该SharedPreferences数据只能被应用程序读写
(2).Context.MODE_WORLD_READABLE:指定该SharedPreferences数据能被其他应用程序读，但不能写。
(3).Context,MODE_WORLD_WRITEABLE:指定该SharedPreferences数据能被其他应用程序写，但不能读。
步骤2：得到 SharedPreferences.Editor编辑对象
SharedPreferences.Editor editor=sp.edit();
步骤3：添加数据 
editor.putBoolean(key,value)
editor.putString()
editor.putInt() 
editor.putFloat()
editor.putLong()
步骤4：提交数据 editor.commit()

    private void write() {//TODO  1:得到SharedPreferences对象//参数一 xml文件的名字 参数二 模式 MODE_PRIVATE 指定该SharedPreferences数据只能被本应用程序读写SharedPreferences preferences = getSharedPreferences("songdingxing", MODE_PRIVATE);//TODO 2:获得编辑对象SharedPreferences.Editor editor = preferences.edit();//TODO 3:写数据editor.putString("username","送定型");editor.putInt("age",18);editor.putBoolean("isMan",false);editor.putFloat("price",12.4f);editor.putLong("id",5425054250l);//TODO 4:提交数据editor.commit();}

2.获取数据

步骤1：得到SharedPreferences对象 getSharedPreferences(“文件的名称”,“文件的类型”);
步骤2：读取数据 String msg = sp.getString(key,defValue);

    private void read() {//TODO  1:得到SharedPreferences对象//参数一 xml文件的名字 参数二 模式 MODE_PRIVATE 指定该SharedPreferences数据只能被本应用程序读写SharedPreferences preferences = getSharedPreferences("songdingxing", MODE_PRIVATE);//TODO 2：直接读取//参数一 键  参数二 找不到的时候给默认值String username=preferences.getString("username","");int age=preferences.getInt("age",0);boolean isMan=preferences.getBoolean("isMan",false);float price=preferences.getFloat("price",0.0f);long id=preferences.getLong("id",0l);Toast.makeText(this, username+":"+age+":"+isMan+":"+price+"："+id, Toast.LENGTH_SHORT).show();}

二、文件存储 内部存储+SD卡存储

三、SD卡存储

    public static void write_json(String json)  {//判断是否挂载if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){//获取SD卡根路径：mnt/shell/emulated/0File file=Environment.getExternalStorageDirectory();FileOutputStream fos=null;try {//创建输出流fos= new FileOutputStream(new File(file,"json.txt"));fos.write(json.getBytes());} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally{try {fos.close();} catch (IOException e) {e.printStackTrace();}}}}

四、SD卡读取

   public static String read_json() {if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {File file = Environment.getExternalStorageDirectory();FileInputStream fis= null;StringBuffer sb=new StringBuffer();try {fis=new FileInputStream(new File(file,"json.txt"));byte[] b=new byte[1024];int len=0;while((len=fis.read(b))!=-1){sb.append(new String(b,0,len));}} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally{try {fis.close();} catch (IOException e) {e.printStackTrace();}}return  sb.toString();}else{return "";}}

五、三级存储

1.网络获取

public static byte[] getPicByte(String url){byte[] returnByte = null;try {URL url1 = new URL(url);HttpURLConnection urlconn = (HttpURLConnection) url1.openConnection();urlconn.setRequestMethod("GET");urlconn.connect();if(urlconn.getResponseCode()==200){InputStream is = urlconn.getInputStream();ByteArrayOutputStream bos = new ByteArrayOutputStream();int len=-1;byte[] bytes = new byte[1024];while((len=is.read(bytes))!=-1){bos.write(bytes,0,len);}returnByte = bos.toByteArray();}} catch (Exception e) {e.printStackTrace();}return  returnByte;}

2.SD卡读取与写入

//读取public static File getDatas(){if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){File path = Environment.getExternalStorageDirectory();File file = new File(path,"abc.jpg");if(file.exists()){return file;}else{return null;}}return null;}
//写入public static void writeDatas(byte[] b){FileOutputStream fos=null;if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){File path = Environment.getExternalStorageDirectory();File file = new File(path,"abc.jpg");try {file.createNewFile();fos = new  FileOutputStream(file);fos.write(b);} catch (Exception e) {e.printStackTrace();}finally {try {fos.close();} catch (IOException e) {e.printStackTrace();}}}}

3.内存的获取与写入

    LruCache<String,Object> lruCache;public CacheTools(){int maxMemory = (int) Runtime.getRuntime().maxMemory();lruCache = new LruCache<String,Object>(maxMemory/8){@Overrideprotected int sizeOf(String key, Object value) {return super.sizeOf(key, value);}};}
//写入public void addDatas(String k,Object v){if(lruCache.get(k)==null){lruCache.put(k,v);}}
//读取public Object reaDatas(String k){return lruCache.get(k);}

3.主类中判断

private void getPicture() {Bitmap tutu = (Bitmap) cacheTools.reaDatas("图图");Log.e("###lruCache", String.valueOf(tutu));if(tutu!=null){imageView.setImageBitmap(tutu);Log.e("###111","通过内存");}else{File file = SDCardTools.getDatas();if(file!=null){Bitmap bitmap = BitmapFactory.decodeFile(file.getAbsolutePath());imageView.setImageBitmap(bitmap);cacheTools.addDatas("图图",bitmap);Log.e("###111","通过SD");}else{try {byte[] b = new MyAscyncTask().execute("http://www.qubaobei.com/ios/cf/uploadfile/132/9/8289.jpg").get();if(b.length>0){Bitmap bitmap = BitmapFactory.decodeByteArray(b, 0, b.length);cacheTools.addDatas("图图",bitmap);imageView.setImageBitmap(bitmap);SDCardTools.writeDatas(b);Log.e("###111","通过网络");}} catch (Exception e) {e.printStackTrace();}}}}