本地数据存储

本地数据存储的两种方式
1.Sharefrence 私有空间
2.sdk外部存储空间

Sharefarence

1.获取sharefarence实例对象，通过getShareference("文件名"，读写方式)
Sharefarence mSharefarence= getShareference("name",Context.MODE.PRIVATE)
是支持单线程读写操作的
2.再获取Editor对象。通过sharefarence.edit();
3.增加键值editor.putString("KEY","VALUE").putInt("Key","value").commit();
4.获取键值：sharefarence.getString("KEY")
应用场景：开关，通知状态等

内部存储器卡

1.接通路径：File cacheDir=getCacheDir()
2.创建文件：File parentDir=new File(cacheDir,"mycache")
3.判断主目录是否存在：
if（！parentDir.exsits()）{
  parentDir.mkdirs()
}
File file=new File(parentDir,"mytxt")
file.write("内容")
file.flush();
file.close();
获取值

FileReader filereader=new FileRear(文件)
ButterReader bt=new ButterReader(filereader);
String line=null;
while((line=bt.readLine())!=null){
       log.e(line);
    bt.close();
filereader.close();
//记得关闭流,捕获异常
}

外部存储sdk(注：以下代码不是手写输入)

1.添加权限
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
挂载/卸载
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
2.判断sdk是否可读
    if (!TextUtils.equals(Environment.getExternalStorageState(), Environment.MEDIA_MOUNTED)) {
            return;
        }
        File fileDir=Environment.getExternalStorageDirectory();
        File parentDir=new File(fileDir,"cache");
        if (!parentDir.exists()){
            parentDir.mkdir();
        }
        File file=new File(parentDir,"my.txt");
        try {
            FileWriter fileWriter=new FileWriter(file);
            fileWriter.write("this is a file");
            fileWriter.flush();;
            fileWriter.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

        //read
        try {
            FileReader fileReader=new FileReader(file);
            BufferedReader bufferedReader=new BufferedReader(fileReader);
            String line=null;
            while ((line=bufferedReader.readLine())!=null){
                Log.e("lxn","line"+line);
            }
            
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }