第八天 SharedPreferences存储SD卡储存和

最新推荐文章于 2021-06-04 21:33:58 发布

hjh_devils

最新推荐文章于 2021-06-04 21:33:58 发布

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分类专栏： android 第一月

本文链接：https://blog.youkuaiyun.com/weixin_44965867/article/details/99240626

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本文深入讲解了安卓应用中数据存储的两种常见方式：SharedPreferences和SD卡文件存储。详细介绍了如何使用SharedPreferences进行数据的写入与读取，包括字符串、整型、布尔型、浮点型和长整型数据的处理。同时，文章提供了SD卡文件存储的实现步骤，从权限申请到数据的写入和读取全过程。

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SharedPreferences

写数据

        SharedPreferences preferences = getSharedPreferences("songdingxing", MODE_PRIVATE);
        SharedPreferences.Editor editor = preferences.edit();
        editor.putString("username","送定型");
        editor.putInt("age",18);
        editor.putBoolean("isMan",false);
        editor.putFloat("price",12.4f);
        editor.putLong("id",5425054250l); 
        editor.commit();

读数据

    SharedPreferences preferences = getSharedPreferences("sgf", MODE_PRIVATE);
        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();

SD卡储存

SD卡介绍：
一般手机文件管理根路径 /storage/emulated/0/或者/mnt/shell/emulated/0

写数据

   //获得运行时的权限
        requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE,Manifest.permission.READ_EXTERNAL_STORAGE},100);
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
                    //获取SD卡的路径
                    File file = Environment.getExternalStorageDirectory();
                    FileOutputStream out=null;
                    try {
                        out = new FileOutputStream(new File(file, "aaa.txt"));
                        out.write("哈哈哈哈".getBytes());
                        out.flush();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }finally {
                        if(out!=null){
                            try {
                                out.close();
                            } catch (IOException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                }

读数据


               
 //获得运行时的权限
        requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE,Manifest.permission.READ_EXTERNAL_STORAGE},100);               if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
                    File file = Environment.getExternalStorageDirectory();
                    FileInputStream inputStream=null;
                    StringBuffer sb =new StringBuffer();
                    try {
                        inputStream = new FileInputStream(new File(file, "aaa.txt"));
                        byte[] bytes = new byte[1024];
                        int len=0;
                        while ((len=inputStream.read(bytes))!=-1){
                           sb.append(new String(bytes,0,len));
                        }
                        showId.setText(sb.toString());
                        Log.i(TAG, "onClick: "+sb.toString());
                    } catch (Exception e) {
                        e.printStackTrace();
                    }finally {
                        if(inputStream!=null){
                            try {
                                inputStream.close();
                            } catch (IOException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                }